ESP32-C3 SuperMini

Tags: chip:ESP32-C3

The ESP32-C3 SuperMini is a compact third-party board based on the Espressif ESP32-C3 RISC-V SoC.

Typical boards include native USB-C (USB Serial/JTAG), 4 MB flash, 2.4 GHz Wi-Fi, Bluetooth 5 (LE), an onboard user LED, and BOOT/RESET buttons.

../../../../../_images/ESP32-C3-SuperMini-headers.jpg

Header silkscreen (V1601)
../../../../../_images/ESP32-C3-SuperMini-usb.jpg

USB-C, BOOT, RESET, and status LED

Note

SuperMini is not an official Espressif board. Pin labels, LED color, flash size, and antenna layout can vary between vendors. Confirm GPIO8 (LED) and GPIO9 (BOOT) against the silkscreen on your module.

This page documents SuperMini-specific pins and NuttX configurations. Toolchain install, flashing, debugging, and peripheral support are in the main ESP32-C3 documentation.

Espressif’s larger DevKit boards are documented at ESP32-C3 DevKit.

Features

  • 32-bit RISC-V single-core processor, up to 160 MHz

  • 400 KB SRAM and typically 4 MB on-board flash

  • USB Type-C with the ESP32-C3 USB Serial/JTAG controller

  • 2.4 GHz Wi-Fi (802.11 b/g/n) and Bluetooth 5 (LE)

  • Header GPIOs: GPIO0 to GPIO10, GPIO20, GPIO21

  • 1 RESET button, 1 BOOT button, 1 onboard user LED

Buttons and LEDs

Board Buttons

There are two buttons labeled BOOT and RESET. The RESET button is not available to software. It pulls the chip enable line that doubles as a reset line.

The BOOT button is connected to GPIO9. On reset it is used as a strapping pin to determine whether the chip boots normally or into the serial bootloader. After reset, the BOOT button can be used as a software input.

To enter download mode: hold BOOT, tap RESET, then release BOOT.

Board LEDs

Typical SuperMini boards have a user LED on GPIO8. The LED is active-low (drive the pin low to turn it on). GPIO8 is also a strapping pin and must remain high during reset, so do not attach external circuitry that pulls it low at boot.

Pin Mapping

The V1601 silkscreen uses two rows of eight pads. USB-C is at the end next to 5V/GND. USB D-/D+ (GPIO18/GPIO19) stay on the USB-C connector and are not broken out.

Header row next to 5V (USB toward GPIO0):

5V  G  3.3  4  3  2  1  0

Header row next to GPIO5 (USB toward GPIO21):

5  6  7  8  9  10  20  21

GPIO functions:

Pin

Signal

Notes

GPIO0

ADC1_CH0; preferred general-purpose I/O

GPIO1

ADC1_CH1; preferred general-purpose I/O

GPIO2

ADC1_CH2; strapping pin (keep high at boot)

GPIO3

ADC1_CH3

GPIO4

ADC1_CH4; JTAG MTMS

GPIO5

ADC2_CH0; JTAG MTDI (ADC2 is limited while Wi-Fi is on)

GPIO6

SPI2 CLK; JTAG MTCK

GPIO7

SPI2 MOSI; JTAG MTDO

GPIO8

Onboard LED (active-low); strapping pin

GPIO9

BOOT button; strapping pin

GPIO10

SPI2 CS

GPIO18

USB_D-

USB-C only

GPIO19

USB_D+

USB-C only

GPIO20

U0RXD

UART0 RX (nsh serial console)

GPIO21

U0TXD

UART0 TX (nsh serial console)

5V

USB 5 V / external 5 V (do not combine with USB 5 V)

3V3

3.3 V rail

GND

Ground

Do not apply more than 3.3 V to GPIO pins.

I2C is routed through the GPIO matrix and has no fixed SuperMini pins. GPIO8/GPIO9 are a poor I2C choice because they are strapping pins and share the LED and BOOT button. Prefer GPIO0/GPIO1 or GPIO1/GPIO3.

NSH Console

usbnsh exposes NuttShell over the USB-C CDC/ACM port. This is the usual way to use SuperMini without an external USB-UART adapter.

nsh uses UART0 on GPIO20 (RX) and GPIO21 (TX) at 115200 8N1. Connect an external 3.3 V USB-UART adapter if you use that configuration.

Installation

  1. Configure and build NuttX (USB console):

$ git clone https://github.com/apache/nuttx.git nuttx
$ git clone https://github.com/apache/nuttx-apps.git apps
$ cd nuttx
$ make distclean
$ ./tools/configure.sh esp32c3-supermini:usbnsh
$ make V=1

  1. Put the board in download mode if needed, then flash with esptool:

make flash ESPTOOL_PORT=/dev/ttyACM0 ESPTOOL_BINDIR=./

The USB Serial/JTAG device is typically /dev/ttyACM0. External USB-UART adapters are typically /dev/ttyUSB0.

Configurations

All configurations listed below can be selected with:

$ ./tools/configure.sh esp32c3-supermini:<config_name>

nsh

Basic NuttShell configuration using UART0 (GPIO21 TX / GPIO20 RX) at 115200 bps.

usbnsh

Basic NuttShell configuration using CDC/ACM serial over the USB-C port at 115200 bps.

NuttShell (NSH) NuttX-12.8.0
nsh> uname -a
NuttX 12.8.0 ... risc-v esp32c3-supermini

gpio

NuttShell over USB, plus the GPIO example. The onboard LED is registered as an output and GPIO0 as an interrupt input:

PIN/GPIO

Mode

Device

GPIO8

Output

/dev/gpio0 (LED, active-low)

GPIO0

Interrupt

/dev/gpio1

Writing 0 to /dev/gpio0 turns the LED on; writing 1 turns it off.

nsh> gpio -o 0 /dev/gpio0
Driver: /dev/gpio0
  Output pin:    Value=1
  Writing:       Value=0
  Verify:        Value=0
nsh> gpio -o 1 /dev/gpio0
Driver: /dev/gpio0
  Output pin:    Value=0
  Writing:       Value=1
  Verify:        Value=1

wifi

This configuration enables a wlan network interface that can be configured and initialized using:

nsh> ifup wlan0
nsh> wapi psk wlan0 mypasswd 3
nsh> wapi essid wlan0 myssid 1
nsh> renew wlan0

That associates with SSID myssid using password mypasswd. The IP address is obtained via DHCP with renew. Check the result with ifconfig.