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ESP32C3 Dev Module
Official ESP32-C3 development board with full GPIO access - ideal for prototyping secure, low-power IoT devices.
ESP32-C3
RISC-V MCU
160MHz
clock
4MB
flash
400KB
SRAM
12· 6 ADC
GPIO
BLE 5.0+ WiFi
radio
Pinout
12 pins
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | A0 | safe | adc | |
| 2 | 1 | A1 | safe | adc | |
| 3 | 2 | A2 | strapping | adc | |
| 4 | 3 | A3 | safe | adc | |
| 5 | 4 | SCKA4 | strapping | adc · spi | |
| 6 | 5 | MISOA5 | strapping | adc · spi | |
| 7 | 6 | MOSI | strapping | spi | |
| 8 | 7 | SS | strapping | spi | |
| 9 | 8 | LED_BUILTINSDA | strapping | i2c | |
| 10 | 9 | SCL | strapping | i2c | |
| 11 | 20 | RX | uart | uart | |
| 12 | 21 | TX | uart | uart |
Start with these
3 pins with no boot or system involvementA0A1A3
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 |
|---|---|---|---|
| A2 | GPIO2 | Must be held high during boot (if low on reset, normal flash boot may fail) | Strapping |
| SCK | MTMS | Used during boot; JTAG TMS for debugging; acts as Quad-SPI flash IO (hold data line) in internal-flash variants | JTAG |
| MISO | MTDI | Used during boot; JTAG TDI for debugging; acts as Quad-SPI flash IO (write-protect data line) in internal-flash variants | JTAG |
| MOSI | MTCK | Used during boot; JTAG TCK for debugging; provides flash clock 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 |
| LED_BUILTIN | GPIO8 | Must be held high during reset (if low, UART flashing/boot may not work) | Strapping |
| SCL | GPIO9 | Controls boot mode on reset (HIGH for normal flash boot, LOW enters serial download mode) | Strapping |
| 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 |
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 All 12 pins on the ESP32C3 Dev Module are usable GPIO. Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO8 and SCL on GPIO9; the SPI bus ( MOSI…
All 12 pins on the ESP32C3 Dev Module are usable GPIO.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO8 and SCL on GPIO9; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO21 and GPIO20 cover serial logging and flashing.
Beyond plain digital I/O you get 6 ADC-capable pins for sensors and battery monitoring.
9 of the exposed pins carry boot-time or system duties on the ESP32-C3 (A2, SCK, MISO and 6 more) - check the guidance above before wiring anything to them. A0, A1 and A3 are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutes1
Connect over USB
Serial chip: onboard. Not detected? Hold BOOT while plugging in.
2
Flash with your tool
Arduino IDE, PlatformIO, ESPHome or esptool - copy the settings on the right.
3
Verify it runs
The blink example uses GPIO0 - swap for your board's LED pin if different.
Board: Esp32c3 Dev
Flash Size: 4MB · QIO
Upload Speed: 921600
// blink
pinMode(0, OUTPUT);
digitalWrite(0, LOW); // on (often inverted)[env:esp32c3]
platform = espressif32
board = esp32-c3-devkitm-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32:
board: esp32-c3-devkitm-1
variant: esp32c3
framework:
type: esp-idf
# blink - GPIO0
output:
- platform: gpio
pin: 0
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesptool.py --chip esp32c3 --port /dev/ttyACM0 \
write_flash 0x0 firmware.binBuild details: sketch space 1310720 B · data 327680 B · QIO
Specifications
ESP32-C3Compute
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
-
Serial
-
Boot address
0x0
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
QIO · QIO
Sketch · Data
1.25 MB · 320 KB
The ESP32C3 Dev Module uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is QIO with QIO boot mode. The maximum sketch size is 1.25 MB with 320 KB available for data.
About this board
Inside sits the ESP32-C3 - a single-core RISC-V and the budget low-power pick.
Around the module: Reset/Boot buttons.
Resources
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