Espressif ESP8684 RISC-V WiFi & BLE MCU embeds up to 4MB flash in a 4x4mm package

Espressif Systems ESP8684 is a single-core RISC-V microcontroller with 2.4 GHz WiFi 4 and Bluetooth 5.0  LE (BLE) connectivity that also integrates 1, 2, or 4MB flash into a tiny 4x4mm QFN package.

The SoC is listed under the ESP32-C2 product family on the Espressif website and can be found in MINI and WROOM modules, as well as the ESP8684-DevKitM-1 development kit. All three parts, namely ESP8684H1, ESP8684H2, and ESP8684H4, are designed to work in the -40 to 105°C temperature range,

ESP8684 WiFi BLE SoC

ESP8684 specifications:

  • CPU –  32-bit RISC-V processor up to 120 MHz;  305.42 CoreMark; 2.55 CoreMark/MHz
  • Memory – 272 KB SRAM (16 KB for cache)
  • Storage – 576 KB ROM, 1 to 4MB flash (SiP)
  • Wireless
    • 802.11 b/g/n-compliant WiFi 4 1T1R
      • Up to 72.2 Mbps link rate
      • Support for 20 MHz bandwidth
      • Station mode, SoftAP mode, Station + SoftAP mode
      • Wi-Fi Multimedia (WMM)
      • Antenna diversity
    • Bluetooth 5 LE up to 20 dBm power, 2 Mbps data rate
  • Peripherals
    • 14x programmable GPIOs
    • 3x SPI, 2x UART, 1x I2C Master
    • LED PWM controller with up to 6 channels
    • General DMA controller (GDMA), with 1 transmit channel and 1 receive channel
    • 12-bit SAR ADC, up to 5 channels
    • Temperature sensor
    • Timers – 54-bit general-purpose timer, 2x watchdog timers, 52-bit system timer
  • Security
    • Secure boot
    •  Flash encryption
    • 1024-bit OTP, up to 256 bits
    • Crypto accelerator for SHA, ECC
    • Random Number Generator (RNG)
  • Low Power Management – Power Management Unit with four power modes
  • Package – QFN24 4x4mm

While the company calls the ESP8684 an “SoC”, it’s more like a SiP (system-in-package) with ESP32-C3 and SPI flash as explained on ESP32 forums:

ESP8684 has an ESP32-C2 silicon die packaged together with (some amount of) flash in a 4×4 mm QFN-28 package…
ESP32-C2 is a lower-end chip compared to ESP32-C3, with less RAM and peripherals… I can’t say yet whether ESP32-C2 will be marketed and sold only as part of ESP8684 package or separately as well.

There’s also an ESP8685 combining an ESP32-C3 die with a 2MB flash in a 4×4 mm QFN-28 package, but let’s focus on the “ESP32-C2” part in this post.

ESP8684 ESP32-C2 modules
ESP8684 “ESP32-C2” modules

Espressif Systems (will) offer the chip in eight different modules:

  • ESP8684-MINI-1 – 53 pins, 13.2×16.6×2.4 mm, PCB antenna
  • ESP8684-WROOM-01C – 22 pins, 24×16×3.1 mm, PCB antenna
  • ESP8684-WROOM-02C – 18 pins, 18x20x3.2 mm, PCB antenna
  • ESP8684-WROOM-03 – 11 pins, 15×17.3×2.8 mm, PCB antenna
  • ESP8684-WROOM-04C – 17 pins, 24×16×3.1 mm, PCB antenna
  • ESP8684-WROOM-05 – 7 pins, 15×17.3×2.8 mm, PCB antenna
  • ESP8684-WROOM-06C – 21 pins, 15.8×20.3×2.7 mm, PCB antenna
  • ESP8684-WROOM-07 – 6 pins, 8.5×12.7×1.9 mm, PCB antenna

Note that all those modules are only offered with 2MB or 4MB SPI flash, except the ESP8684-MINI-1 that’s available with 1, 2, or 4MB flash. Right now we only have information in Chinese about the modules, but I suppose it will be provided in English very soon.

ESP8684-DevKitM-1There’s also the ESP8684-DevKitM-1 development board based on ESP8684-MINI-1 module with a micro USB port for power and programming, pin headers for I/Os, Reset and Boot buttons, and an RGB LED. A wiki in English provides detailed instructions to get started with the ESP-IDF framework or the ESP-AT software in case you’d want to use the board/module as a wireless coprocessor.

ESP8684 development board

At the time only the ESP8684-MINI-1-H4 or H2 and the ESP8684-DevKitM-1 development board are available outside of China. More specifically, you can purchase the modules for $1.80 to $1.90 and the development kit for $10.50 on Mouser. [Update: I can see LCSC has some WROOM modules as well, or even just the ESP8684H1 SiP going for 44 cents per unit for 1k+ orders.]

You’ll find more details and documentation such as the datasheet and technical reference manual on the Espressif Systems website.

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