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AirM2M_CORE_ESP32C3
Compact ESP32-C3 core board - suitable for integrating Wi-Fi and BLE into custom embedded designs.
51 × 21 mm
ESP32-C3
RISC-V MCU
160MHz
clock
4MB
flash
400KB
SRAM
12· 6 ADC
GPIO
BLE 5.0+ WiFi
radio
Pinout
12 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | A0 | safe | adc | |
| 2 | 1 | A1 | safe | adc | |
| 3 | 2 | SCKA2 | strapping | adc · spi | |
| 4 | 3 | MOSIA3 | safe | adc · spi | |
| 5 | 4 | SDAA4 | strapping | adc · i2c | |
| 6 | 5 | SCLA5 | strapping | adc · i2c | |
| 7 | 7 | SS | strapping | spi | |
| 8 | 10 | MISO | safe | spi | |
| 9 | 12 | LED_BUILTIN | strapping | - | |
| 10 | 13 | LED_BUILTIN_AUX | strapping | - | |
| 11 | 20 | RX | uart | uart | |
| 12 | 21 | TX | uart | uart |
Start with these
4 pins with no boot or system involvementA0A1MOSIA3MISO
Freely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
sampled at boot or shared with debug/serial| Pin | Label | What to know | Role |
|---|---|---|---|
| SCK | GPIO2 | Must be held high during boot (if low on reset, normal flash boot may fail) | Strapping |
| SDA | MTMS | Used during boot; JTAG TMS for debugging; acts as Quad-SPI flash IO (hold data line) in internal-flash variants | JTAG |
| SCL | MTDI | Used during boot; JTAG TDI for debugging; acts as Quad-SPI flash IO (write-protect data line) in internal-flash variants | JTAG |
| SS | MTDO | Used during boot; JTAG TDO for debugging; acts as Quad-SPI flash IO (data line) in internal-flash variants | JTAG |
| RX | U0RXD | Used as UART0 receive (console/bootloader); repurposing may disable serial programming and debug logs | UART |
| TX | U0TXD | Used as UART0 transmit (console/bootloader); repurposing may disable serial console output and printing | UART |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| LED_BUILTIN | SPIHD | Connected to flash HOLD#; not recommended for other use as it’s reserved for flash communication | Flash |
| LED_BUILTIN_AUX | SPIWP | Connected to flash WP#; not recommended for other use (used to interface with SPI flash) | Flash |
These are recommendations, not hard rules - with the right pull-ups, timing and boot-state awareness most pins can be made to work. When in doubt, start green.
Pinout notes The AirM2M_CORE_ESP32C3 pinout brings out 12 GPIO pins at a 2.54 mm pitch - every one of them usable in your project. For peripherals, I²C is mapped to SDA on…
The AirM2M_CORE_ESP32C3 pinout brings out 12 GPIO pins at a 2.54 mm pitch - every one of them usable in your project.
For peripherals, I²C is mapped to SDA on GPIO4 and SCL on GPIO5; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO21 and GPIO20 cover serial logging and flashing.
On the analog side there are 6 ADC-capable pins for sensors and battery monitoring.
If you want zero surprises, A0, A1, MOSI and MISO are free of any such role - the safest first picks. 6 of the exposed pins carry boot-time or system duties on the ESP32-C3 (SCK, SDA, SCL and 3 more).
Getting started
flash your first firmware in ~2 minutes1
Connect over USB
Install your USB-serial driver (CH340 / CP210x) if no port appears. Not detected? Hold BOOT while plugging in.
2
Match & flash
Set the Tools options shown, then click Upload.
3
Verify it runs
The onboard LED on GPIO0 blinks - swap the pin if your board's LED differs.
Set these in Tools · leave everything else at default
Arduino IDE 2.x — Tools Copy
Board: "ESP32C3 Dev Module"▸
Flash Size: "4MB (32Mb)"▸
Flash Mode: "DIO"▸
Partition Scheme: "Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS)" (default)▸
Upload Speed: "921600"▸
▸ every other Tools option — leave at default
Board: ESP32C3 Dev Module Flash Size: 4MB (32Mb) Flash Mode: DIO Partition Scheme: Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS) Upload Speed: 921600
Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32C3 Dev Module
// blink the onboard LED
void setup() {
pinMode(0, OUTPUT);
}
void loop() {
digitalWrite(0, HIGH); delay(500);
digitalWrite(0, LOW); delay(500);
}board to selectesp32-c3-devkitm-1⧉ copy
[env:AirM2M_CORE_ESP32C3]
platform = espressif32
board = esp32-c3-devkitm-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600Find it: PlatformIO Home ▸ Boards, search
esp32-c3-devkitm-1 — or type it after board =.board to selectesp32-c3-devkitm-1⧉ copy
esp32:
board: esp32-c3-devkitm-1
variant: AirM2M_CORE_ESP32C3
framework:
type: esp-idf
# blink - GPIO0
output:
- platform: gpio
pin: 0
id: led_out
light:
- platform: binary
name: "LED"
output: led_outFind it: search ESPHome's board list for
esp32-c3-devkitm-1 (same ids as PlatformIO).esptool doesn't pick board settings — a prebuilt .bin already has them baked in. This is just the raw flash command.
esptool.py --chip esp32c3 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Build details: sketch space 1310720 B · data 327680 B · DIO
Specifications
ESP32-C3 · 51 × 21 mmCompute
MCU
ESP32-C3 · RISC-V
Clock
160 MHz
SRAM · Flash
400 KB · 4MB
Radio
Wi-Fi
802.11 b/g/n
Bluetooth
5.0 LE
Antenna
PCB
I/O
GPIO · ADC
12 · 6
UART · I²C · SPI
2 · 1 · 3
PWM
6 channels
Power
USB
USB-C
Serial
CH343
Boot address
0x0
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · DIO
Sketch · Data
1.25 MB · 320 KB
51 × 21 mm · pin pitch 2.54 mm
The AirM2M_CORE_ESP32C3 uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with DIO boot mode. The maximum sketch size is 1.25 MB with 320 KB available for data.
About this board
At its core is the ESP32-C3 - a single-core RISC-V and the budget low-power pick.
Onboard you'll find status LEDs (D4, D5) and Reset/Boot buttons.
Where to buy
prices are typical street pricesAirM2M_CORE_ESP32C3
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Resources
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