ESP32 C3 Super Mini

Board summary
- Specifications
ESPHome support
Pinout
Enter bootloader mode to program over USB
References

Board summary

Manufacturer	Maker go
Board docs (C3 mini)	C3 Mini
Datasheet (C3 series)	`esp32_c3_datasheet.pdf`¹
Technical Reference Manual	`esp32-c3_technical_reference_manual_en.pdf`
Schematic	`esp32-c3-supermini-schematic.png`
Pinout	`esp32_c3_supermini_pinout.jpg` (topside), `esp32_c3_supermini_pinout_under.jpg` (underside)
Microsoft	ESP32-C3 SuperMini
PlatformIO	Espressif ESP32-C3-DevKitM-1²
Announcement	Introducing ESP32-C3
ESPHome platform	ESP32 Platform³
Recomended framework	`esp-idf`⁴
ESPHome config	`packages/boards/esp32c3supermini.yaml`⁵

ESP32 C3 Super mini

Specifications

Name
Chipset	`ESP32-C3 FN4 (172023 P3L7730)`
Wi-Fi	2.4 GHz b/g/n
Bluetooth	BLE 5
Processor	32-bit RISC-V single-core
Clock speed	$160 M Hz$
SRAM	`320 KB`
PSRAM	N/A
Flash	`4 MB`
Flash frequency	$80 M Hz$
Flash mode	`QIO`
Operating voltage	$3, 3 V$
Supply voltage	$3, 0 - 3, 6 V$

ESPHome support

Board config:

esp32:
  board: esp32-c3-devkitm-1
  variant: ESP32C3
  framework:
    type: esp-idf

esphome:
  platformio_options:
    board_build.flash_mode: dio

Config for status_led (on GPIO8):

light:
  - platform: status_led
    name: "Status LED"
    id: esp_status_led
    icon: "mdi:alarm-light"
    pin:
      number: GPIO8
      inverted: true
    restore_mode: ALWAYS_OFF

Pinout

Interfaces

The ESP32 C3 series has 2x ADCs, 6x PWM channels, 2x UART, 1x I²C and 3x SPI⁶.

Interface	Pins	Notes
ADC1	`GPIO0`-`GPIO4`
ADC2	`GPIO5`	Not usable when Wi-Fi is enabled⁶.
UART	Any GPIO pins
LED PWM	Any GPIO pins	6x PWM channels
I²C	Any GPIO pins
SPI0	None	Used by internal GDMA controller
SPI1	None	Used by CPU
SPI2	Any

Pin mappings:

Silkscreen pin	Internal pin	Notes
`0`	`GPIO0`	`ADC1`
`1`	`GPIO1`	`ADC1`
`2`	`GPIO2`	`ADC1`, boot mode / strapping pin
`3`	`GPIO3`	`ADC1`
`4`	`GPIO4`	`ADC1`, JTAG
`5`	`GPIO5`	JTAG
`6`	`GPIO6`	JTAG
`7`	`GPIO7`	JTAG
`8`	`GPIO8`	Blue `status_led` (inverted), boot mode / strapping pin
`9`	`GPIO9`	Boot mode / strapping pin, boot button
`10`	`GPIO10`
`20`	`GPIO20`
`21`	`GPIO21`

Some notes on pins:

The blue status_led is on GPIO8 and is inverted.
The Wemos C3 Mini documentation shows a RGB led on GPIO8, but that might be on the C3 Mini only (and not SuperMini). Using status_led it toggles a blue on-board LED on the C3 Super Mini.
The BOOT button is wired to GPIO9
JTAG is available on GPIO4 - GPIO7.

Strapping pins

GPIO pin	Default	Controls
`GPIO2`	Floating	Boot mode
`GPIO8`	Floating	Boot mode, ROM message printing
`GPIO9`	Pull-up	Boot mode

Boot modes

Mode	`GPIO2`	`GPIO8`	`GPIO9`
SPI boot (default)	`HIGH`	Any	`HIGH`
UART/JTAG download	`HIGH`	`HIGH`	`LOW`

Enter bootloader mode to program over USB

If the ESP C3 SuperMini is unprogrammed, it seems to enter bootloader mode by default when plugged in with USB. If it has been programmed, it will connect and disconnected. To put the ESP32 C3 SuperMini into bootloader mode (if it is connecting/disconnected, or has been programmed):

Plug in USB
Hold both buttons
Release both buttons at the same time

Before you press the buttons it will connect and disconnect.

Watching dmesg while you do this is helpful:

$ sudo dmesg -w

usb 3-2: Product: USB JTAG/serial debug unit
usb 3-2: Manufacturer: Espressif
cdc_acm 3-2:1.0: ttyACM0: USB ACM device

usb 3-2: USB disconnect, device number 89

On Linux (Fedora) it show up as /dev/ttyACM0 (or ttyACM1 etc).