1 Module Overview 1.1 Features 1.2 Series Comparison 1.3 Applications 2 Block Diagram 3 Pin Definitions 3.1 Pin Layout 3.2 Pin Description 4 Boot Configurations 4.1 Chip Boot Mode Control 4.2 ROM Messages Printing Control 4.3 Chip Power-up and Reset 5 Peripherals 5.1 Peripheral Overview 5.2 Peripheral Description 5.2.1 Connectivity Interface 5.2.1.1 UART Controller 5.2.1.2 SPI Controller 5.2.1.3 I2C Controller 5.2.1.4 I2S Controller 5.2.1.5 USB Serial/JTAG Controller 5.2.1.6 Two-wire Automotive Interface 5.2.1.7 LED PWM Controller 5.2.1.8 Remote Control Peripheral 5.2.2 Analog Signal Processing 5.2.2.1 SAR ADC 5.2.2.2 Temperature Sensor 6 Electrical Characteristics 6.1 Absolute Maximum Ratings 6.2 Recommended Operating Conditions 6.3 DC Characteristics (3.3 V, 25 °C) 6.4 Current Consumption Characteristics 6.4.1 RF Current Consumption in Active Mode 6.4.2 Current Consumption in Other Modes 6.5 Memory Specifications 7 RF Characteristics 7.1 Wi-Fi Radio 7.1.1 Wi-Fi RF Transmitter (TX) Characteristics 7.1.2 Wi-Fi RF Receiver (RX) Characteristics 7.2 Bluetooth 5 (LE) Radio 7.2.1 Bluetooth LE RF Transmitter (TX) Characteristics 7.2.2 Bluetooth LE RF Receiver (RX) Characteristics 8 Module Schematics 9 Peripheral Schematics 10 Module Dimensions 11 PCB Layout Recommendations 11.1 PCB Land Pattern 11.2 Module Placement for PCB Design 12 Product Handling 12.1 Storage Conditions 12.2 Electrostatic Discharge (ESD) 12.3 Reflow Profile 12.4 Ultrasonic Vibration Datasheet Versioning Related Documentation and Resources Revision History ESP8685-WROOM-04 Datasheet Version 1.5 2.4 GHz Wi-Fi (802.11b/g/n) and Bluetooth ® 5 module Built around ESP8685 series of SoC, RISC-V single-core microprocessor 4 MB flash in chip package 13 GPIOs On-board PCB antenna ESP8685-WROOM-04 www.espressif.com 1 Module Overview 1 Module Overview Note: Check the link or the QR code to make sure that you use the latest version of this document: https://espressif.com/documentation/esp8685-wroom-04_datasheet_en.pdf 1.1 Features CPU and On-Chip Memory • ESP8685H4 embedded, 32-bit RISC-V single-core processor, up to 160 MHz • 384 KB ROM • 400 KB SRAM (16 KB for cache) • 8 KB SRAM in RTC • 4 MB flash in chip package Wi-Fi • IEEE 802.11b/g/n-compliant • Center frequency range of operating channel: 2412 ~ 2484 MHz • Supports 20 MHz, 40 MHz bandwidth in 2.4 GHz band • 1T1R mode with data rate up to 150 Mbps • Wi-Fi Multimedia (WMM) • TX/RX A-MPDU, TX/RX A-MSDU • Immediate Block ACK • Fragmentation and defragmentation • Transmit opportunity (TXOP) • Automatic Beacon monitoring (hardware TSF) • 4 × virtual Wi-Fi interfaces • Simultaneous support for Infrastructure BSS in Station mode, SoftAP mode, Station + SoftAP mode, and promiscuous mode Note that when ESP8685 scans in Station mode, the SoftAP channel will change along with the Station channel • 802.11mc FTM Bluetooth ® • Bluetooth LE: Bluetooth 5, Bluetooth mesh • Speed: 125 Kbps, 500 Kbps, 1 Mbps, 2 Mbps • Advertising extensions • Multiple advertisement sets • Channel selection algorithm #2 • Internal co-existence mechanism between Wi-Fi and Bluetooth to share the same antenna Peripherals • Up to 13 GPIOs – 3 strapping GPIOs • SPI, UART, I2C, I2S, remote control peripheral, LED PWM controller, general DMA controller, TWAI ® controller (compatible with ISO 11898-1, i.e. CAN Specification 2.0), USB Serial/JTAG controller, temperature sensor, SAR ADC, general-purpose timers, watchdog timers Note: * Please refer to ESP8685 Series Datasheet for de- tailed information about the module peripherals. Integrated Components on Module • 40 MHz crystal oscillator Antenna Options • On-board PCB antenna Espressif Systems 2 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 1 Module Overview Operating Conditions • Operating voltage/Power supply: 3.0 ~ 3.6 V • Operating ambient temperature: –40 ~ 105 °C Certification • RF certification: See certificates • Green certification: RoHS/REACH Test • HTOL/HTSL/uHAST/TCT/ESD 1.2 Series Comparison ESP8685-WROOM-04 is a powerful, generic Wi-Fi and Bluetooth LE module that has a rich set of peripherals. This module is an ideal choice for smart homes, industrial automation, health care, consumer electronics, etc. ESP8685-WROOM-04 comes with an on-board PCB antenna. The series comparison for ESP8685-WROOM-04 is as follows: Table 1-1. ESP8685-WROOM-04 Series Comparison Ordering Code Flash Ambient Temp. 1 (°C) Size 2 (mm) ESP8685-WROOM-04-H4 4 MB (Quad SPI) 3, 4 –40 ~ 105 24.0 × 16.0 × 3.1 1 Ambient temperature specifies the recommended temperature range of the environment immedi- ately outside the Espressif module. 2 For details, refer to Section 10 Module Dimensions. 3 The flash is in the chip package. For specifications, refer to Section 6.5 Memory Specifications. 4 By default, the SPI flash on the module operates at a maximum clock frequency of 80 MHz and does not support the auto suspend feature. If you have a requirement for a higher flash clock frequency of 120 MHz or if you need the flash auto suspend feature, please contact us. At the core of this module is the ESP8685H4 chip. ESP8685 series of chips have a 32-bit RISC-V single-core processor. They integrate a rich set of peripherals, ranging from UART, I2C, I2S, remote control peripheral, LED PWM controller, general DMA controller, TWAI ® controller, USB Serial/JTAG controller, temperature sensor, and ADC. Note: For more information on ESP8685 chip series, please refer to ESP8685 Series Datasheet. 1.3 Applications • Smart Home • Industrial Automation • Health Care • Consumer Electronics • Smart Agriculture • POS Machines • Service Robot • Audio Devices • Generic Low-power IoT Sensor Hubs • Generic Low-power IoT Data Loggers Espressif Systems 3 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 Contents Contents 1 Module Overview 2 1.1 Features 2 1.2 Series Comparison 3 1.3 Applications 3 2 Block Diagram 8 3 Pin Definitions 9 3.1 Pin Layout 9 3.2 Pin Description 9 4 Boot Configurations 11 4.1 Chip Boot Mode Control 12 4.2 ROM Messages Printing Control 13 4.3 Chip Power-up and Reset 13 5 Peripherals 15 5.1 Peripheral Overview 15 5.2 Peripheral Description 15 5.2.1 Connectivity Interface 15 5.2.1.1 UART Controller 15 5.2.1.2 SPI Controller 15 5.2.1.3 I2C Controller 16 5.2.1.4 I2S Controller 17 5.2.1.5 USB Serial/JTAG Controller 17 5.2.1.6 Two-wire Automotive Interface 17 5.2.1.7 LED PWM Controller 18 5.2.1.8 Remote Control Peripheral 18 5.2.2 Analog Signal Processing 18 5.2.2.1 SAR ADC 18 5.2.2.2 Temperature Sensor 19 6 Electrical Characteristics 20 6.1 Absolute Maximum Ratings 20 6.2 Recommended Operating Conditions 20 6.3 DC Characteristics (3.3 V, 25 °C) 20 6.4 Current Consumption Characteristics 21 6.4.1 RF Current Consumption in Active Mode 21 6.4.2 Current Consumption in Other Modes 21 6.5 Memory Specifications 22 7 RF Characteristics 23 7.1 Wi-Fi Radio 23 Espressif Systems 4 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 Contents 7.1.1 Wi-Fi RF Transmitter (TX) Characteristics 23 7.1.2 Wi-Fi RF Receiver (RX) Characteristics 24 7.2 Bluetooth 5 (LE) Radio 25 7.2.1 Bluetooth LE RF Transmitter (TX) Characteristics 25 7.2.2 Bluetooth LE RF Receiver (RX) Characteristics 27 8 Module Schematics 29 9 Peripheral Schematics 30 10 Module Dimensions 31 11 PCB Layout Recommendations 32 11.1 PCB Land Pattern 32 11.2 Module Placement for PCB Design 32 12 Product Handling 34 12.1 Storage Conditions 34 12.2 Electrostatic Discharge (ESD) 34 12.3 Reflow Profile 34 12.4 Ultrasonic Vibration 35 Datasheet Versioning 36 Related Documentation and Resources 37 Revision History 38 Espressif Systems 5 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 List of Tables List of Tables 1-1 ESP8685-WROOM-04 Series Comparison 3 3-1 Pin Definitions 10 4-1 Default Configuration of Strapping Pins 11 4-2 Description of Timing Parameters for the Strapping Pins 12 4-3 Chip Boot Mode Control 12 4-4 UART0 ROM Message Printing Control 13 4-5 USB Serial/JTAG ROM Message Printing Control 13 4-6 Description of Timing Parameters for Power-up and Reset 14 6-1 Absolute Maximum Ratings 20 6-2 Recommended Operating Conditions 20 6-3 DC Characteristics (3.3 V, 25 °C) 20 6-4 Current Consumption for Wi-Fi (2.4 GHz) in Active Mode 21 6-5 Current Consumption in Modem-sleep Mode 21 6-6 Current Consumption in Low-Power Modes 22 6-7 Flash Specifications 22 7-1 Wi-Fi RF Characteristics 23 7-2 TX Power with Spectral Mask and EVM Meeting 802.11 Standards 23 7-3 TX EVM Test 23 7-4 RX Sensitivity 24 7-5 Maximum RX Level 25 7-6 RX Adjacent Channel Rejection 25 7-7 Bluetooth LE RF Characteristics 25 7-8 Bluetooth LE - Transmitter Characteristics - 1 Mbps 25 7-9 Bluetooth LE - Transmitter Characteristics - 2 Mbps 26 7-10 Bluetooth LE - Transmitter Characteristics - 125 Kbps 26 7-11 Bluetooth LE - Transmitter Characteristics - 500 Kbps 26 7-12 Bluetooth LE - Receiver Characteristic - 1 Mbps 27 7-13 Bluetooth LE - Receiver Characteristic - 2 Mbps 27 7-14 Bluetooth LE - Receiver Characteristic - 125 Kbps 28 7-15 Bluetooth LE - Receiver Characteristic - 500 Kbps 28 Espressif Systems 6 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 List of Figures List of Figures 2-1 Block Diagram 8 3-1 Pin Layout (Top View) 9 4-1 Visualization of Timing Parameters for the Strapping Pins 12 4-2 Visualization of Timing Parameters for Power-up and Reset 14 8-1 Schematics 29 9-1 Peripheral Schematics 30 10-1 Physical Dimensions 31 11-1 Recommended PCB Land Pattern 32 12-1 Reflow Profile 34 Espressif Systems 7 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 2 Block Diagram 2 Block Diagram SPI Flash ESP8685 RF Matching 40 MHz Crystal 3V3 ESP8685-WROOM-04 EN GPIOs Antenna Figure 2-1. Block Diagram Espressif Systems 8 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 3 Pin Definitions 3 Pin Definitions 3.1 Pin Layout The pin diagram below shows the approximate location of pins on the module. For the actual diagram drawn to scale, please refer to Figure 10 Module Dimensions. Keepout Zone IO0 1 IO1 2 EN 3 IO2 4 IO4 5 IO5 6 IO6 7 TXD016 3V3 8 RXD015 IO3 14 IO10 13 IO9 12 IO811 IO7 10 GND 9 17 GND GND GND GND GND GND GNDGND GND A Figure 3-1. Pin Layout (Top View) Note A: The zone marked with dotted lines is the antenna keepout zone. To learn more about the keepout zone for module’s antenna on the base board, please refer to ESP32-C3 Hardware Design Guidelines > Section General Principles of PCB Layout for Modules. 3.2 Pin Description The module has 17 pins. See pin definitions in Table 3-1 Pin Definitions. For peripheral pin configurations, please refer to ESP8685 Series Datasheet. Espressif Systems 9 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 3 Pin Definitions Table 3-1. Pin Definitions Name No. Type 1 Function IO0 1 I/O/T GPIO0�ADC1_CH0, XTAL_32K_P IO1 2 I/O/T GPIO1, ADC1_CH1, XTAL_32K_N EN 3 I High: on, enables the chip. Low: off, the chip powers off. By default, this pin is internally pulled high. IO2 4 I/O/T GPIO2, ADC1_CH2, FSPIQ IO4 5 I/O/T GPIO4, ADC1_CH4, FSPIHD, MTMS, LED PWM IO5 6 I/O/T GPIO5, ADC2_CH0, FSPIWP, MTDI, LED PWM IO6 7 I/O/T GPIO6, FSPICLK, MTCK, LED PWM 3V3 8 P Power supply GND 9,17 P Ground IO7 10 I/O/T GPIO7, FSPID, MTDO, LED PWM IO8 11 I/O/T GPIO8 IO9 12 I/O/T GPIO9 IO10 13 I/O/T GPIO10, FSPICS0, LED PWM IO3 14 I/O/T GPIO3, ADC1_CH3, LED PWM RXD0 15 I/O/T GPIO20, U0RXD TXD0 16 I/O/T GPIO21, U0TXD 1 P: power supply; I: input; O: output; T: high impedance. Espressif Systems 10 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 4 Boot Configurations 4 Boot Configurations Note: The content below is excerpted from ESP8685 Series Datasheet > Chapter Boot Configurations. For the strapping pin mapping between the chip and modules, please refer to Chapter 8 Module Schematics. The chip allows for configuring the following boot parameters through strapping pins and eFuse parameters at power-up or a hardware reset, without microcontroller interaction. • Chip boot mode – Strapping pins: GPIO2, GPIO8, and GPIO9 • ROM message printing – Strapping pin: GPIO8 – eFuse parameters: EFUSE_UART_PRINT_CONTROL and EFUSE_USB_PRINT_CHANNEL The default values of all the above eFuse parameters are 0, which means that they are not burnt. Given that eFuse is one-time programmable, once programmed to 1, it can never be reverted to 0. For how to program eFuse parameters, please refer to ESP32-C3 Technical Reference Manual > Chapter eFuse Controller. The default values of the strapping pins, namely the logic levels, are determined by pins’ internal weak pull-up/pull-down resistors at reset if the pins are not connected to any circuit, or connected to an external high-impedance circuit. Table 4-1. Default Configuration of Strapping Pins Strapping Pin Default Configuration Bit Value GPIO2 Floating – GPIO8 Floating – GPIO9 Weak pull-up 1 To change the bit values, the strapping pins should be connected to external pull-down/pull-up resistances. If the ESP8685 is used as a device by a host MCU, the strapping pin voltage levels can also be controlled by the host MCU. All strapping pins have latches. At Chip Reset, the latches sample the bit values of their respective strapping pins and store them until the chip is powered down or shut down. The states of latches cannot be changed in any other way. It makes the strapping pin values available during the entire chip operation, and the pins are freed up to be used as regular IO pins after reset. For details on Chip Reset, see ESP32-C3 Technical Reference Manual > Chapter Reset and Clock. The timing of signals connected to the strapping pins should adhere to the setup time and hold time specifications in Table 4-2 and Figure 4-1. Espressif Systems 11 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 4 Boot Configurations Table 4-2. Description of Timing Parameters for the Strapping Pins Parameter Description Min (ms) t SU Setup time is the time reserved for the power rails to stabilize before the CHIP_EN pin is pulled high to activate the chip. 0 t H Hold time is the time reserved for the chip to read the strapping pin values after CHIP_EN is already high and before these pins start operating as regular IO pins. 3 Strapping pin V IH_nRST V IH t SU t H CHIP_EN Figure 4-1. Visualization of Timing Parameters for the Strapping Pins 4.1 Chip Boot Mode Control GPIO2, GPIO8, and GPIO9 control the boot mode after the reset is released. See Table 4-3 Chip Boot Mode Control. Table 4-3. Chip Boot Mode Control Boot Mode GPIO2 2 GPIO8 GPIO9 SPI boot mode 1 Any value 1 Joint download boot mode 3 1 1 0 1 Bold marks the default value and configuration. 2 GPIO2 actually does not determine SPI Boot and Joint Down- load Boot mode, but it is recommended to pull this pin up due to glitches. 3 Joint Download Boot mode supports the following download methods: • USB-Serial-JTAG Download Boot • UART Download Boot In SPI Boot mode, the ROM bootloader loads and executes the program from SPI flash to boot the system. Espressif Systems 12 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 4 Boot Configurations In Joint Download Boot mode, users can download binary files into flash using UART0 or USB interface. It is also possible to download binary files into SRAM and execute it from SRAM. In addition to SPI Boot and Joint Download Boot modes, ESP8685 also supports SPI Download Boot mode. For details, please see ESP32-C3 Technical Reference Manual > Chapter Chip Boot Control. 4.2 ROM Messages Printing Control During the boot process, the messages by the ROM code can be printed to: • (Default) UART0 and USB Serial/JTAG controller • UART0 • USB Serial/JTAG controller EFUSE_UART_PRINT_CONTROL and GPIO8 control ROM messages printing to UART0 as shown in Table 4-4 UART0 ROM Message Printing Control. Table 4-4. UART0 ROM Message Printing Control UART0 ROM Code Printing EFUSE_UART_PRINT_CONTROL GPIO8 Enabled 0 Ignored 1 0 2 1 Disabled 1 1 2 0 3 Ignored 1 Bold marks the default value and configuration. EFUSE_USB_PRINT_CHANNEL controls the printing to USB Serial/JTAG controller as shown in Table 4-5 USB Serial/JTAG ROM Message Printing Control. Table 4-5. USB Serial/JTAG ROM Message Printing Control USB Serial/JTAG ROM Code Printing EFUSE_DIS_USB_SERIAL_JTAG 2 EFUSE_USB_PRINT_CHANNEL Enabled 0 0 Disabled 0 1 1 Ignored 1 Bold marks the default value and configuration. 2 EFUSE_DIS_USB_SERIAL_JTAG controls whether to disable USB Serial/JTAG. 4.3 Chip Power-up and Reset Once the power is supplied to the chip, its power rails need a short time to stabilize. After that, CHIP_EN – the pin used for power-up and reset – is pulled high to activate the chip. For information on CHIP_EN as well as power-up and reset timing, see Figure 4-2 and Table 4-6. Espressif Systems 13 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 4 Boot Configurations V IL_nRST t ST BL t RST 2.8 V VDDA, VDD3P3, VDD3P3_RTC, VDD3P3_CPU CHIP_EN Figure 4-2. Visualization of Timing Parameters for Power-up and Reset Table 4-6. Description of Timing Parameters for Power-up and Reset Parameter Description Min (µs) t ST BL Time reserved for the power rails of VDDA, VDD3P3, VDD3P3_RTC, and VDD3P3_CPU to stabilize before the CHIP_EN pin is pulled high to activate the chip 50 t RST Time reserved for CHIP_EN to stay below V IL_nRST to reset the chip (see Table 6-3) 50 Espressif Systems 14 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 5 Peripherals 5 Peripherals 5.1 Peripheral Overview ESP8685H4 integrates a rich set of peripherals including SPI, I2S, UART, I2C, RMT, LED PWM controller, TWAI ® controller, USB Serial/JTAG controller, temperature sensor, etc. To learn more about on-chip components, please refer to ESP8685 Series Datasheet > Section Functional Description. Note: The content below is sourced from ESP8685 Series Datasheet > Section Peripherals. Some information may not be ap- plicable to ESP8685-WROOM-04 as not all the IO signals are exposed on the module. To learn more about peripheral signals, please refer to ESP32-C3 Technical Reference Manual > Section Peripheral Signal List. 5.2 Peripheral Description This section describes the chip’s peripheral capabilities, covering connectivity interfaces and on-chip sensors that extend its functionality. 5.2.1 Connectivity Interface This subsection describes the connectivity interfaces on the chip that enable communication and interaction with external devices and networks. 5.2.1.1 UART Controller ESP8685 has two UART interfaces, i.e. UART0 and UART1, which support IrDA and asynchronous communication (RS232 and RS485) at a speed of up to 5 Mbps. The UART controller provides hardware flow control (CTS and RTS signals) and software flow control (XON and XOFF). Both UART interfaces connect to GDMA via UHCI0, and can be accessed by the GDMA controller or directly by the CPU. For details, see ESP32-C3 Technical Reference Manual > Chapter UART Controller (UART, LP_UART). Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.1.2 SPI Controller ESP8685 has the following SPI interfaces: • SPI0 used by ESP8685’s GDMA controller and cache to access in-package flash • SPI1 used by the CPU to access in-package flash • SPI2 is a general purpose SPI controller with access to a DMA channel allocated by the GDMA controller Espressif Systems 15 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 5 Peripherals Features of SPI0 and SPI1 • Supports Single SPI, Dual SPI, and Quad SPI, QPI modes • Configurable clock frequency with a maximum of 120 MHz in Single Transfer Rate (STR) mode • Data transmission is in bytes Features of SPI2 • Supports operation as a master or slave • Connects to a DMA channel allocated by the GDMA controller • Supports Single SPI, Dual SPI, and Quad SPI, QPI • Configurable clock polarity (CPOL) and phase (CPHA) • Configurable clock frequency • Data transmission is in bytes • Configurable read and write data bit order: most-significant bit (MSB) first, or least-significant bit (LSB) first • As a master – Supports 2-line full-duplex communication with clock frequency up to 80 MHz – Supports 1-, 2-, 4-line half-duplex communication with clock frequency up to 80 MHz – Provides six SPI_CS pins for connection with six independent SPI slaves – Configurable CS setup time and hold time • As a slave – Supports 2-line full-duplex communication with clock frequency up to 60 MHz – Supports 1-, 2-, 4-line half-duplex communication with clock frequency up to 60 MHz For details, see ESP32-C3 Technical Reference Manual > Chapter SPI Controller (SPI). Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.1.3 I2C Controller ESP8685 has an I2C bus interface which is used for I2C master mode or slave mode, depending on your configuration. The I2C interface supports: • standard mode (100 Kbit/s) • fast mode (400 Kbit/s) • up to 800 Kbit/s (constrained by SCL and SDA pull-up strength) • 7-bit and 10-bit addressing mode • double addressing mode Espressif Systems 16 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 5 Peripherals • 7-bit broadcast address For details, see ESP32-C3 Technical Reference Manual > Chapter I2C Controller (I2C). Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.1.4 I2S Controller ESP8685 includes a standard I2S interface. This interface can operate as a master or a slave in full-duplex mode or half-duplex mode, and can be configured for 8-bit, 16-bit, 24-bit, or 32-bit serial communication. BCK clock frequency, from 10 kHz up to 40 MHz, is supported. The I2S interface connects to the GDMA controller. The interface supports TDM PCM, TDM MSB alignment, TDM standard, and PDM standard. For details, see ESP32-C3 Technical Reference Manual > Chapter I2S Controller (I2S). Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.1.5 USB Serial/JTAG Controller ESP8685 integrates a USB Serial/JTAG controller. This controller has the following features: • CDC-ACM virtual serial port and JTAG adapter functionality • USB 2.0 full speed compliant, capable of up to 12 Mbit/s transfer speed (Note that this controller does not support the faster 480 Mbit/s high-speed transfer mode) • programming in-package flash • CPU debugging with compact JTAG instructions • a full-speed USB PHY integrated in the chip For details, see ESP32-C3 Technical Reference Manual > Chapter USB Serial/JTAG Controller (USB_SERIAL_JTAG). Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.1.6 Two-wire Automotive Interface ESP8685 has a TWAI ® controller with the following features: • compatible with ISO 11898-1 protocol (CAN Specification 2.0) • standard frame format (11-bit ID) and extended frame format (29-bit ID) • bit rates from 1 Kbit/s to 1 Mbit/s • multiple modes of operation: Normal, Listen Only, and Self-Test (no acknowledgment required) Espressif Systems 17 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 5 Peripherals • 64-byte receive FIFO • acceptance filter (single and dual filter modes) • error detection and handling: error counters, configurable error interrupt threshold, error code capture, arbitration lost capture For details, see ESP32-C3 Technical Reference Manual > Chapter Two-wire Automotive Interface. Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.1.7 LED PWM Controller The LED PWM controller can generate independent digital waveform on six channels. The LED PWM controller: • Can generate digital waveform with configurable periods and duty cycle. The resolution of duty cycle can be up to 14 bits. • Has multiple clock sources, including APB clock and external main crystal clock. • Can operate when the CPU is in Light-sleep mode. • Supports gradual increase or decrease of duty cycle, which is useful for the LED RGB color-gradient generator. For details, see ESP32-C3 Technical Reference Manual > Chapter LED PWM Controller. Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.1.8 Remote Control Peripheral The Remote Control Peripheral (RMT) supports two channels of infrared remote transmission and two channels of infrared remote reception. By controlling pulse waveform through software, it supports various infrared and other single wire protocols. All four channels share a 192 × 32-bit memory block to store transmit or receive waveform. For more details, see ESP32-C3 Technical Reference Manual > Chapter Remote Control Peripheral (RMT). Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.2 Analog Signal Processing This subsection describes components on the chip that sense and process real-world data. 5.2.2.1 SAR ADC ESP8685 integrates two 12-bit SAR ADCs. Espressif Systems 18 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 5 Peripherals • ADC1 supports measurements on 5 channels, and is factory-calibrated. • ADC2 supports measurements on 1 channel, and is not factory-calibrated. Note: ADC2 of some chip revisions is not operable. For details, please refer to ESP32-C3 Series SoC Errata. For more details, see ESP32-C3 Technical Reference Manual > Chapter On-Chip Sensors and Analog Signal Processing. Pin Assignment For details, see ESP8685 Series Datasheet > Section Peripheral Pin Assignment. 5.2.2.2 Temperature Sensor The temperature sensor generates a voltage that varies with temperature. The voltage is internally converted via an ADC into a digital value. The temperature sensor has a range of –40 °C to 125 °C. It is designed primarily to sense the temperature changes inside the chip. The temperature value depends on factors like microcontroller clock frequency or I/O load. Generally, the chip’s internal temperature is higher than the operating ambient temperature. For more details, see ESP32-C3 Technical Reference Manual > Chapter On-Chip Sensors and Analog Signal Processing. Espressif Systems 19 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 6 Electrical Characteristics 6 Electrical Characteristics 6.1 Absolute Maximum Ratings Stresses above those listed in Table 6-1 Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under Table 6-2 Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Table 6-1. Absolute Maximum Ratings Symbol Parameter Min Max Unit VDD33 Power supply voltage –0.3 3.6 V T ST ORE Storage temperature –40 105 °C 6.2 Recommended Operating Conditions Table 6-2. Recommended Operating Conditions Symbol Parameter Min Typ Max Unit VDD33 Power supply voltage 3.0 3.3 3.6 V I V DD Current delivered by external power supply 0.5 — — A T A Operating ambient temperature –40 — 105 °C 6.3 DC Characteristics (3.3 V, 25 °C) Table 6-3. DC Characteristics (3.3 V, 25 °C) Parameter Description Min Typ Max Unit C IN Pin capacitance — 2 — pF V IH High-level input voltage 0.75 × VDD 1 — VDD 1 + 0.3 V V IL Low-level input voltage –0.3 — 0.25 × VDD 1 V I IH High-level input current — — 50 nA I IL Low-level input current — — 50 nA V OH 2 High-level output voltage 0.8 × VDD 1 — — V V OL 2 Low-level output voltage — — 0.1 × VDD 1 V I OH High-level source current (VDD 1 = 3.3 V, V OH >= 2.64 V, PAD_DRIVER = 3) — 40 — mA I OL Low-level sink current (VDD 1 = 3.3 V, V OL = 0.495 V, PAD_DRIVER = 3) — 28 — mA R P U Internal weak pull-up resistor — 45 — kΩ R P D Internal weak pull-down resistor — 45 — kΩ Espressif Systems 20 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 6 Electrical Characteristics V IH_nRST Chip reset release voltage (CHIP_EN voltage is within the specified range) 0.75 × VDD 1 — VDD 1 + 0.3 V V IL_nRST Chip reset voltage (CHIP_EN voltage is within the specified range) –0.3 — 0.25 × VDD 1 V 1 VDD – voltage from a power pin of a respective power domain. 2 V OH and V OL are measured using high-impedance load. 6.4 Current Consumption Characteristics 6.4.1 RF Current Consumption in Active Mode The current consumption measurements are taken with a 3.3 V supply at 25 °C ambient temperature. TX current consumption is rated at a 100% duty cycle. RX current consumption is rated when the peripherals are disabled and the CPU idle. Table 6-4. Current Consumption for Wi-Fi (2.4 GHz) in Active Mode Work mode RF Condition Description Peak (mA) Active (RF working) TX 802.11b, 1 Mbps, @20 dBm 330 802.11g, 54 Mbps, @17.5 dBm 280 802.11n, HT20, MCS7, @17 dBm 275 802.11n, HT40, MCS7, @16.5 dBm 202 RX 802.11b/g/n, HT20 82 802.11n, HT40 84.5 Note: The content below is excerpted from Section Power Consumption in Other Modes in ESP8685 Series Datasheet. 6.4.2 Current Consumption in Other Modes Table 6-5. Current Consumption in Modem-sleep Mode Typ Mode CPU Frequency (MHz) Description All Peripherals Clocks Disabled (mA) All Peripherals Clocks Enabled (mA) 1 Modem-sleep 2,3 160 CPU is running 23 28 CPU is idle 16 21 80 CPU is running 17 22 CPU is idle 13 18 1 In practice, the current consumption might be different depending on which peripherals are enabled. 2 In Modem-sleep mode, Wi-Fi is clock gated. 3 In Modem-sleep mode, the consumption might be higher when accessing flash. For a flash rated at 80 Mbit/s, in SPI 2-line mode the consumption is 10 mA. Espressif Systems 21 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 6 Electrical Characteristics Table 6-6. Current Consumption in Low-Power Modes Mode Description Typ (µA) Light-sleep Wi-Fi are powered down, and all GPIOs are high-impedance 130 Deep-sleep RTC timer + RTC memory 5 Power off CHIP_EN is set to low level, the chip is powered off 1 6.5 Memory Specifications The data below is sourced from the memory vendor datasheet. These values are guaranteed through design and/or characterization but are not fully tested in production. Devices are shipped with the memory erased. Table 6-7. Flash Specifications Parameter Description Min Typ Max Unit VCC Power supply voltage (1.8 V) 1.65 1.80 2.00 V Power supply voltage (3.3 V) 2.7 3.3 3.6 V F C Maximum clock frequency 80 — — MHz — Program/erase cycles 100,000 — — cycles T RET Data retention time 20 — — years T P P Page program time — 0.8 5 ms T SE Sector erase time (4 KB) — 70 500 ms T BE1 Block erase time (32 KB) — 0.2 2 s T BE2 Block erase time (64 KB) — 0.3 3 s T CE Chip erase time (16 Mb) — 7 20 s Chip erase time (32 Mb) — 20 60 s Chip erase time (64 Mb) — 25 100 s Chip erase time (128 Mb) — 60 200 s Chip erase time (256 Mb) — 70 300 s Espressif Systems 22 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 7 RF Characteristics 7 RF Characteristics This section contains tables with RF characteristics of the Espressif product. The RF data is measured at the antenna port, where RF cable is connected, including the front-end loss. Devices should operate in the center frequency range allocated by regional regulatory authorities. The target center frequency range and the target transmit power are configurable by software. See ESP RF Test Tool and Test Guide for instructions. Unless otherwise stated, the RF tests are conducted with a 3.3 V (±5%) supply at 25 ºC ambient temperature. 7.1 Wi-Fi Radio Table 7-1. Wi-Fi RF Characteristics Name Description Center frequency range of operating channel 2412 ~ 2484 MHz Wi-Fi wireless standard IEEE 802.11b/g/n 7.1.1 Wi-Fi RF Transmitter (TX) Characteristics Table 7-2. TX Power with Spectral Mask and EVM Meeting 802.11 Standards Min Typ Max Rate (dBm) (dBm) (dBm) 802.11b, 1 Mbps — 20.0 — 802.11b, 11 Mbps — 20.0 — 802.11g, 6 Mbps — 19.5 — 802.11g, 54 Mbps — 17.5 — 802.11n, HT20, MCS0 — 18.5 — 802.11n, HT20, MCS7 — 17.0 — 802.11n, HT40, MCS0 — 18.0 — 802.11n, HT40, MCS7 — 16.5 — Table 7-3. TX EVM Test Min Typ SL 1 Rate (dB) (dB) (dB) 802.11b, 1 Mbps, @20 dBm — –25.5 –10 802.11b, 11 Mbps, @20 dBm — –25.5 –10 802.11g, 6 Mbps, @19.5 dBm — –24.0 –5 802.11g, 54 Mbps, @17.5 dBm — –29.5 –25 802.11n, HT20, MCS0, @18.5 dBm — –24.5 –5 Cont’d on next page Espressif Systems 23 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 7 RF Characteristics Table 7-3 – cont’d from previous page Min Typ SL 1 Rate (dB) (dB) (dB) 802.11n, HT20, MCS7, @17 dBm — –30.0 –27 802.11n, HT40, MCS0, @18 dBm — –27.0 –5 802.11n, HT40, MCS7, @16.5 dBm — –30.0 –27 1 SL stands for standard limit value. 7.1.2 Wi-Fi RF Receiver (RX) Characteristics For RX tests, the PER (packet error rate) limit is 8% for 802.11b, and 10% for 802.11g/n. Table 7-4. RX Sensitivity Min Typ Max Rate (dBm) (dBm) (dBm) 802.11b, 1 Mbps — –98.0 — 802.11b, 2 Mbps — –96.0 — 802.11b, 5.5 Mbps — –93.0 — 802.11b, 11 Mbps — –88.6 — 802.11g, 6 Mbps — –92.8 — 802.11g, 9 Mbps — –92.0 — 802.11g, 12 Mbps — –90.5 — 802.11g, 18 Mbps — –88.0 — 802.11g, 24 Mbps — –85.0 — 802.11g, 36 Mbps — –82.0 — 802.11g, 48 Mbps — –78.0 — 802.11g, 54 Mbps — –76.4 — 802.11n, HT20, MCS0 — –93.0 — 802.11n, HT20, MCS1 — –90.5 — 802.11n, HT20, MCS2 — –88.2 — 802.11n, HT20, MCS3 — –84.5 — 802.11n, HT20, MCS4 — –81.5 — 802.11n, HT20, MCS5 — –78.0 — 802.11n, HT20, MCS6 — –75.5 — 802.11n, HT20, MCS7 — –74.5 — 802.11n, HT40, MCS0 — –90.0 — 802.11n, HT40, MCS1 — –87.0 — 802.11n, HT40, MCS2 — –84.6 — 802.11n, HT40, MCS3 — –81.8 — 802.11n, HT40, MCS4 — –78.0 — 802.11n, HT40, MCS5 — –74.0 — 802.11n, HT40, MCS6 — –72.8 — 802.11n, HT40, MCS7 — –71.2 — Espressif Systems 24 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 7 RF Characteristics Table 7-5. Maximum RX Level Min Typ Max Rate (dBm) (dBm) (dBm) 802.11b, 1 Mbps — 5 — 802.11b, 11 Mbps — 5 — 802.11g, 6 Mbps — 5 — 802.11g, 54 Mbps — 0 — 802.11n, HT20, MCS0 — 5 — 802.11n, HT20, MCS7 — 0 — 802.11n, HT40, MCS0 — 5 — 802.11n, HT40, MCS7 — 0 — Table 7-6. RX Adjacent Channel Rejection Min Typ Max Rate (dB) (dB) (dB) 802.11b, 1 Mbps — 35 — 802.11b, 11 Mbps — 35 — 802.11g, 6 Mbps — 31 — 802.11g, 54 Mbps — 14 — 802.11n, HT20, MCS0 — 31 — 802.11n, HT20, MCS7 — 13 — 802.11n, HT40, MCS0 — 25 — 802.11n, HT40, MCS7 — 13 — 7.2 Bluetooth 5 (LE) Radio Table 7-7. Bluetooth LE RF Characteristics Name Description Center frequency range of operating channel 2402 ~ 2480 MHz RF transmit power range –24.0 ~ 20.0 dBm 7.2.1 Bluetooth LE RF Transmitter (TX) Characteristics Table 7-8. Bluetooth LE - Transmitter Characteristics - 1 Mbps Parameter Description Min Typ Max Unit In-band emissions F = F0 ± 2 MHz — –37.62 — dBm F = F0 ± 3 MHz — –41.95 — dBm F = F0 ± > 3 MHz — –44.48 — dBm Modulation characteristics ∆ f1 avg — 245.00 — kHz ∆ f2 max — 208.00 — kHz Cont’d on next page Espressif Systems 25 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 7 RF Characteristics Table 7-8 – cont’d from previous page Parameter Description Min Typ Max Unit ∆ f2 avg /∆ f1 avg — 0.93 — — Carrier frequency offset — — –9.00 — kHz Carrier frequency drift |f 0 − f n | n=2, 3, 4, ..k — 1.17 — kHz |f 1 − f 0 | — 0.30 — kHz |f n − f n−5 | n=6, 7, 8, ..k — 4.90 — kHz Table 7-9. Bluetooth LE - Transmitter Characteristics - 2 Mbps Parameter Description Min Typ Max Unit In-band emissions F = F0 ± 4 MHz — –43.55 — dBm F = F0 ± 5 MHz — –45.26 — dBm F = F0 ± > 5 MHz — –47.00 — dBm Modulation characteristics ∆ f1 avg — 497.00 — kHz ∆ f2 max — 398.00 — kHz ∆ f2 avg /∆ f1 avg — 0.95 — — Carrier frequency offset — — –9.00 — kHz Carrier frequency drift |f 0 − f n | n=2, 3, 4, ..k — 0.46 — kHz |f 1 − f 0 | — 0.70 — kHz |f n − f n−5 | n=6, 7, 8, ..k — 6.80 — kHz Table 7-10. Bluetooth LE - Transmitter Characteristics - 125 Kbps Parameter Description Min Typ Max Unit In-band emissions F = F0 ± 2 MHz — –37.90 — dBm F = F0 ± 3 MHz — –41.00 — dBm F = F0 ± > 3 MHz — –42.50 — dBm Modulation characteristics ∆ f1 avg — 252.00 — kHz ∆ f1 max — 200.00 — kHz Carrier frequency offset — — –13.70 — kHz Carrier frequency drift |f 0 − f n | n=1, 2, 3, ..k — 1.52 — kHz |f 0 − f 3 | — 0.65 — kHz |f n − f n−3 | n=7, 8, 9, ..k — 0.70 — kHz Table 7-11. Bluetooth LE - Transmitter Characteristics - 500 Kbps Parameter Description Min Typ Max Unit In-band emissions F = F0 ± 2 MHz — –37.90 — dBm F = F0 ± 3 MHz — –41.30 — dBm F = F0 ± > 3 MHz — –42.80 — dBm Modulation characteristics ∆ f2 avg — 220.00 — kHz ∆ f2 max — 205.00 — kHz Carrier frequency offset — — –11.90 — kHz Cont’d on next page Espressif Systems 26 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 7 RF Characteristics Table 7-11 – cont’d from previous page Parameter Description Min Typ Max Unit Carrier frequency drift |f 0 − f n | n=1, 2, 3, ..k — 1.37 — kHz |f 0 − f 3 | — 1.09 — kHz |f n − f n−3 | n=7, 8, 9, ..k — 0.51 — kHz 7.2.2 Bluetooth LE RF Receiver (RX) Characteristics Table 7-12. Bluetooth LE - Receiver Characteristic - 1 Mbps Parameter Description Min Typ Max Unit Sensitivity @30.8% PER — — –96 — dBm Maximum received signal @30.8% PER — — 5 — dBm Co-channel C/I — — 8 — dB Adjacent channel selectivity C/I F = F0 + 1 MHz — –4 — dB F = F0 – 1 MHz — –3 — dB F = F0 + 2 MHz — –32 — dB F = F0 – 2 MHz — –36 — dB F ≥ F0 + 3 MHz (1) — — — dB F ≤ F0 – 3 MHz — –39 — dB Image frequency — — –29 — dB Adjacent channel to image frequency F = F image + 1 MHz — –38 — dB F = F image – 1 MHz — –34 — dB Out-of-band blocking performance 30 MHz ~ 2000 MHz — –9 — dBm 2003 MHz ~ 2399 MHz — –18 — dBm 2484 MHz ~ 2997 MHz — –16 — dBm 3000 MHz ~ 12.75 GHz — –6 — dBm Intermodulation — — –44 — dBm 1 Refer to the value of Adjacent channel to image frequency when F = F image – 1 MHz. Table 7-13. Bluetooth LE - Receiver Characteristic - 2 Mbps Parameter Description Min Typ Max Unit Sensitivity @30.8% PER — — –93 — dBm Maximum received signal @30.8% PER — — 2 — dBm Co-channel C/I — — 10 — dB Adjacent channel selectivity C/I F = F0 + 2 MHz — –7 — dB F = F0 – 2 MHz — –7 — dB F = F0 + 4 MHz (1) — — — dB F = F0 – 4 MHz — –34 — dB F ≥ F0 + 6 MHz — –39 — dB F ≤ F0 – 6 MHz — –39 — dB Image frequency — — –27 — dB Adjacent channel to image frequency F = F image + 2 MHz — –39 — dB Cont’d on next page Espressif Systems 27 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 7 RF Characteristics Table 7-13 – cont’d from previous page Parameter Description Min Typ Max Unit F = F image – 2 MHz (2) — — — dB Out-of-band blocking performance 30 MHz ~ 2000 MHz — –17 — dBm 2003 MHz ~ 2399 MHz — –19 — dBm 2484 MHz ~ 2997 MHz — –16 — dBm 3000 MHz ~ 12.75 GHz — –22 — dBm Intermodulation — — –40 — dBm 1 Refer to the value of Image frequency. 2 Refer to the value of Adjacent channel selectivity C/I when F = F0 + 2 MHz. Table 7-14. Bluetooth LE - Receiver Characteristic - 125 Kbps Parameter Description Min Typ Max Unit Sensitivity @30.8% PER — — –104 — dBm Maximum received signal @30.8% PER — — 5 — dBm Co-channel C/I — — 2 — dB Adjacent channel selectivity C/I F = F0 + 1 MHz — –6 — dB F = F0 – 1 MHz — –5 — dB F = F0 + 2 MHz — –40 — dB F = F0 – 2 MHz — –42 — dB F ≥ F0 + 3 MHz (1) — — — dB F ≤ F0 – 3 MHz — –46 — dB Image frequency — — –34 — dB Adjacent channel to image frequency F = F image + 1 MHz — –44 — dB F = F image – 1 MHz — –37 — dB 1 Refer to the value of Adjacent channel to image frequency when F = F image – 1 MHz. Table 7-15. Bluetooth LE - Receiver Characteristic - 500 Kbps Parameter Description Min Typ Max Unit Sensitivity @30.8% PER — — –99 — dBm Maximum received signal @30.8% PER — — 5 — dBm Co-channel C/I — — 3 — dB Adjacent channel selectivity C/I F = F0 + 1 MHz — –5 — dB F = F0 – 1 MHz — –7 — dB F = F0 + 2 MHz — –39 — dB F = F0 – 2 MHz — –40 — dB F ≥ F0 + 3 MHz (1) — — — dB F ≤ F0 – 3 MHz — –40 — dB Image frequency — — –34 — dB Adjacent channel to image frequency F = F image + 1 MHz — –43 — dB F = F image – 1 MHz — –38 — dB 1 Refer to the value of Adjacent channel to image frequency when F = F image – 1 MHz. Espressif Systems 28 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 8 Module Schematics 8 Module Schematics This is the reference design of the module. 5 5 4 4 3 3 2 2 1 1 D D C C B B A A The values of C8, L2 and C9 vary with the actual PCB board. The values of C1 and C2 vary with the selection of the crystal. The value of R1 varies with the actual PCB board. R1 could be a resistor or inductor, the initial value is suggested to be 24 nH. Pin.10 IO7 Pin.9 GND Pin.2 IO1 Pin.3 EN Pin.4 IO2 Pin.5 IO4 Pin.6 IO5 Pin.7 IO6 Pin.1 IO0 Pin.12 IO9 Pin.11 IO8 PCB ANTENNA Pin.13 IO10 Pin.14 IO3 Pin.15 RXD0 Pin.16 TXD0 Pin.8 3V3 ESP8685-WROOM-04(pin-out) EPAD NC: No component. 50 ohm Impedance Control U0RXD U0TXD GPIO6 GPIO7 GPIO8 GPIO9 CHIP_EN GPIO5 U0RXD U0TXD GPIO4 GPIO2 GPIO0 GPIO1 GPIO3 GPIO10 CHIP_EN LNA_INRF_ANT GPIO2 GPIO0 GPIO1 GPIO4 GPIO5 GPIO3 CHIP_EN GPIO6 GPIO7 GPIO8 GPIO9 GPIO10 GND VDD33 VDD33 GND GND GND VDD33 GND GND VDD33 GND GNDGND GND VDD33 GND GND GND VDD33 VDD33 GND GND VDD33 GND GND GND GND GND Title Size Page Name R ev Date: Sheet o f Confidential and Proprietary <02_ESP8685-WROOM-04> V1.1 ESP8685-WROOM-04 A4 2 2Tuesday, January 09, 2024 Title Size Page Name R ev Date: Sheet o f Confidential and Proprietary <02_ESP8685-WROOM-04> V1.1 ESP8685-WROOM-04 A4 2 2Tuesday, January 09, 2024 Title Size Page Name R ev Date: Sheet o f Confidential and Proprietary <02_ESP8685-WROOM-04> V1.1 ESP8685-WROOM-04 A4 2 2Tuesday, January 09, 2024 R1 0 C1 TBD C3 1uF C13 10uF(NC) C2 TBD D1 ESD U1 40MHz(±10ppm) XIN 1 GND 2 XOUT 3 GND 4 R11 10K R3 10K C8 TBD C12 0.1uF C9 TBD R9 10K(NC) L2 TBD L1 2.0nH(0.1nH) C4 10nF C5 10uF ANT1 PCB_ANT 1 2 C14 1uF R2 499 C6 0.1uF R12 10K(NC) C7 0.1uF U2 ESP8685 LNA_IN 1 VDD3P3 2 VDD3P3 3 XTAL_32K_P 4 XTAL_32K_N 5 GPIO2 6 CHIP_EN 7 MTMS 9 MTDI 10 VDD3P3_RTC 11 MTCK 12 MTDO 13 GPIO8 14 GPIO9 15 GPIO10 16 VDD3P3_CPU 17 U0RXD 23 U0TXD 24 XTAL_N 25 XTAL_P 26 GND 29 GPIO3 8 VDDA 28 VDDA 27 GPIO19 22 GPIO18 21 NC 20 NC 19 NC 18 C10 0.1uF Figure 8-1. Schematics Espressif Systems 29 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 9 Peripheral Schematics 9 Peripheral Schematics This is the typical application circuit of the module connected with peripheral components (for example, power supply, antenna, reset button, JTAG interface, and UART interface). 5 5 4 4 3 3 2 2 1 1 D D C C B B A A EN on the module is pulled up to VDD33 through a 10 K resistor, and connected to GND through a 1 uF capacitor. X1: ESR = Max. 70 K NC: No component. EN IO3 IO4 IO5 IO6 3V3 EN IO9 IO7 RXD TXD IO8 IO10IO2 IO1 IO0 IO4 TMS IO5 TDI IO6 TCK IO7 TDO GND GND VDD33 GND GND GND VDD33 GND GND VDD33 GND GND R30(NC) JP2 Boot Option 1 1 2 2 C7 12pF(NC) X1 32.768KHz(NC) 2 1 R7 NC R50(NC) C2 0.1uF SW1 C4 0.1uF R8 10K R2 0 JP1 JTAG 1 1 2 2 3 3 4 4 U1 ESP8685-WROOM-04 3V3 8 EN 3 IO4 5 IO5 6 IO6 7 IO7 10 IO9 12 GND 9 IO8 11 RXD0 15 TXD0 16 IO3 14 IO10 13 IO2 4 IO1 2 IO0 1 EPAD 17 C8 12pF(NC) JP4 UART 1 1 2 2 3 3 4 4 C3 TBD C1 10uF Figure 9-1. Peripheral Schematics • Soldering the EPAD to the ground of the base board is not a must, however, it can optimize thermal performance. If you choose to solder it, please apply the correct amount of soldering paste. Too much soldering paste may increase the gap between the module and the baseboard. As a result, the adhesion between other pins and the baseboard may be poor. • To ensure that the power supply to the ESP8685 chip is stable during power-up, it is advised to add an RC delay circuit at the EN pin. The recommended setting for the RC delay circuit is usually R = 10 kΩ and C = 1 µF (such RC delay circuit has already been built into the module). However, specific parameters should be adjusted based on the power-up timing of the module and the power-up and reset sequence timing of the chip. For ESP8685’s power-up and reset sequence timing diagram, please refer Section 4.3 Chip Power-up and Reset. • UART0 is used to download firmware and log output. When using the AT firmware, note that the UART GPIO is already configured. It is recommended to use the default configuration. Please refer to ESP-AT User Guide for ESP32-C3 > Section Hardware Connection. Espressif Systems 30 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 10 Module Dimensions 10 Module Dimensions 16±0.15 6 24±0.15 15.15 3.1±0.15 0.8 14 1.5 2 16 x 1.1 10.74 2.8 16 x 0.55 16 x 1.1 16 x 1.2 Unit: mm 16 x Ø0.6 0.93 1.93 Top View Side View Bottom View 2.8 0.5 0.5 0.6 x 0.6 Ø0.5 12.15 6.8 Figure 10-1. Physical Dimensions Note: For information about tape, reel, and product marking, please refer to ESP32-C3 Module Packaging Information. Espressif Systems 31 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 11 PCB Layout Recommendations 11 PCB Layout Recommendations 11.1 PCB Land Pattern This section provides the following resources for your reference: • Figure for the recommended PCB land pattern with all the dimensions needed for PCB design. See Figure 11-1 Recommended PCB Land Pattern. • Source file of the recommended PCB land pattern to measure dimensions not covered in Figure 11-1. You can view the source files for ESP8685-WROOM-04 with Autodesk Viewer. Antenna Area 1 Top View 16 8 6 16 9 1.5 10.74 6.8 Unit: mm Copper Via for thermal pad 8.5 16 x 1.7 16 x 1.1 2 15.3 0.5 0.5 1.5 24 0.6 x 0.6 2.8 2.8 0.5 0.5 Figure 11-1. Recommended PCB Land Pattern 11.2 Module Placement for PCB Design If module-on-board design is adopted, attention should be paid while positioning the module on the base board. The interference of the base board on the module’s antenna performance should be minimized. Espressif Systems 32 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 11 PCB Layout Recommendations For details about module placement for PCB design, please refer to ESP32-C3 Hardware Design Guidelines > Section General Principles of PCB Layout for Modules. Espressif Systems 33 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 12 Product Handling 12 Product Handling 12.1 Storage Conditions The products sealed in moisture barrier bags (MBB) should be stored in a non-condensing atmospheric environment of < 40 °C and 90%RH. The module is rated at the moisture sensitivity level (MSL) of 3. After unpacking, the module must be soldered within 168 hours with the factory conditions 25±5 °C and 60%RH. If the above conditions are not met, the module needs to be baked. 12.2 Electrostatic Discharge (ESD) • Human body model (HBM): ±2000 V • Charged-device model (CDM): ±500 V 12.3 Reflow Profile Solder the module in a single reflow. 50 100 0 150 200 250 200 100 50 150 250 Time (s) 217 25 Preheating 150 – 200 °C 60 – 120 s Ramp-up 25 – 150 °C 60 – 90 s 1 – 3 °C/s Soldering ＞ 217 °C 60 – 90 s Peak temperature: 235 – 250 °C Peak time: 30 – 70 s Soldering time: ＞ 30 s Solder: Sn-Ag-Cu (SAC305) lead-free solder Temperature (°C) 180 230 Cooling ＜ 180 °C –5 ~ –1 °C/s Figure 12-1. Reflow Profile Espressif Systems 34 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 12 Product Handling 12.4 Ultrasonic Vibration Avoid exposing Espressif modules to vibration from ultrasonic equipment, such as ultrasonic welders or ultrasonic cleaners. This vibration may induce resonance in the in-module crystal and lead to its malfunction or even failure. As a consequence, the module may stop working or its performance may deteriorate. Espressif Systems 35 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 Datasheet Versioning Datasheet Versioning Datasheet Version Status Watermark Definition v0.1 ~ v0.5 (excluding v0.5) Draft Confidential This datasheet is under development for products in the design stage. Specifications may change without prior notice. v0.5 ~ v1.0 (excluding v1.0) Preliminary release Preliminary This datasheet is actively updated for products in the verification stage. Specifications may change before mass production, and the changes will be documentation in the datasheet’s Revision History. v1.0 and higher Official release — This datasheet is publicly released for products in mass production. Specifications are finalized, and major changes will be communicated via Product Change Notifications (PCN). Any version — Not Recommended for New Design (NRND) 1 This datasheet is updated less frequently for products not recommended for new designs. Any version — End of Life (EOL) 2 This datasheet is no longer mtained for products that have reached end of life. 1 Watermark will be added to the datasheet title page only when all the product variants covered by this datasheet are not recommended for new designs. 2 Watermark will be added to the datasheet title page only when all the product variants covered by this datasheet have reached end of life. Espressif Systems 36 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 Related Documentation and Resources Related Documentation and Resources Related Documentation • ESP8685 Series Datasheet – Specifications of the ESP8685 hardware. • ESP32-C3 Technical Reference Manual – Detailed information on how to use the ESP8685 memory and peripherals. • ESP32-C3 Hardware Design Guidelines – Guidelines on how to integrate the ESP8685 into your hardware product. • ESP32-C3 Series SoC Errata – Descriptions of known errors in ESP8685 series of SoCs. • Certificates https://espressif.com/en/support/documents/certificates • ESP8685 Product/Process Change Notifications (PCN) https://espressif.com/en/support/documents/pcns?keys=ESP32-C3 • ESP8685 Advisories – Information on security, bugs, compatibility, component reliability. https://espressif.com/en/support/documents/advisories?keys=ESP32-C3 • Documentation Updates and Update Notification Subscription https://espressif.com/en/support/download/documents Developer Zone • ESP-IDF Programming Guide for ESP8685 – Extensive documentation for the ESP-IDF development framework. • ESP-IDF and other development frameworks on GitHub. https://github.com/espressif • ESP32 BBS Forum – Engineer-to-Engineer (E2E) Community for Espressif products where you can post questions, share knowledge, explore ideas, and help solve problems with fellow engineers. https://esp32.com/ • ESP-FAQ – A summary document of frequently asked questions released by Espressif. https://espressif.com/projects/esp-faq/en/latest/index.html • The ESP Journal – Best Practices, Articles, and Notes from Espressif folks. https://blog.espressif.com/ • See the tabs SDKs and Demos, Apps, Tools, AT Firmware. https://espressif.com/en/support/download/sdks-demos Products • ESP8685 Series SoCs – Browse through all ESP8685 SoCs. https://espressif.com/en/products/socs?id=ESP8685 • ESP8685 Series Modules – Browse through all ESP8685-based modules. https://espressif.com/en/products/modules?id=ESP8685 • ESP8685 Series DevKits – Browse through all ESP8685-based devkits. https://espressif.com/en/products/devkits?id=ESP8685 • ESP Product Selector – Find an Espressif hardware product suitable for your needs by comparing or applying filters. https://products.espressif.com/#/product-selector?language=en Contact Us • See the tabs Sales Questions, Technical Enquiries, Circuit Schematic & PCB Design Review, Get Samples (Online stores), Become Our Supplier, Comments & Suggestions. https://espressif.com/en/contact-us/sales-questions Espressif Systems 37 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 Revision History Revision History Date Version Release notes 2025-09-10 v1.5 • Added Section 4.3 Chip Power-up and Reset • Added Section 6.5 Memory Specifications • Section 9 Peripheral Schematics: Added a note about AT communication using UART0 • Added Datasheet Versioning 2024-07-29 v1.4 • Updated the position of locating holes and the way to show EPAD dimen- sions in Chapter 10 Module Dimensions • Improved the wording and structure of following sections: – Updated Section ”Strapping Pins” and renamed to 4 Boot Configura- tions – Added Chapter 5 Peripherals – Updated Table ”Wi-Fi RF Standards” and renamed to ”Wi-Fi RF Char- acteristics” 2024-02-06 v1.3 • Removed the end-of-life ESP8685-WROOM-04-H2 variant 2024-01-15 v1.2 • Updated Section 6.4.2 Current Consumption in Other Modes • Updated ”RF power control range” in Table Bluetooth LE RF Characteristics • Updated Module Schematics • Updated Peripheral Schematics, note 1, and note 2 • Added descriptions and link of the source file in Section 11.1 PCB Land Pattern 2022-04-26 v1.1 • Updated Section Module Schematics • Updated Section Peripheral Schematics 2022-04-20 v1.0 • Updated Section Bluetooth 5 (LE) Radio • Added a new chip variant 2021-07-01 v0.6 • Deleted Section ”About This Document” • Updated Section ”Peripheral Schematics” • Updated Section ”Learning Resources” and renamed to ”Related Docu- mentation and Resources” • Replaced ”chip family” with ”chip series” following Espressif’s taxonomy 2021-06-11 v0.5 Preliminary release 2021-05-10 v0.1 Draft Cont’d on next page Espressif Systems 38 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 Revision History Cont’d from previous page Date Version Release notes Espressif Systems 39 Submit Documentation Feedback ESP8685-WROOM-04 Datasheet v1.5 Disclaimer and Copyright Notice Information in this document, including URL references, is subject to change without notice. ALL THIRD PARTY’S INFORMATION IN THIS DOCUMENT IS PROVIDED AS IS WITH NO WARRANTIES TO ITS AUTHENTICITY AND ACCURACY. NO WARRANTY IS PROVIDED TO THIS DOCUMENT FOR ITS MERCHANTABILITY, NON-INFRINGEMENT, FITNESS FOR ANY PARTICULAR PURPOSE, NOR DOES ANY WARRANTY OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION OR SAMPLE. All liability, including liability for infringement of any proprietary rights, relating to use of information in this document is disclaimed. No licenses express or implied, by estoppel or otherwise, to any intellectual property rights are granted herein. The Wi-Fi Alliance Member logo is a trademark of the Wi-Fi Alliance. The Bluetooth logo is a registered trademark of Bluetooth SIG. All trade names, trademarks and registered trademarks mentioned in this document are property of their respective owners, and are hereby acknowledged. Copyright © 2025 Espressif Systems (Shanghai) Co., Ltd. All rights reserved. www.espressif.com