ESP32-C3 GPIO9
Everything you need to use this pin correctly: status, alternate functions, boot-time cautions and working code.
| Status | Usable |
|---|---|
| Alternate functions | Strapping (low = download mode) |
| Chip | ESP32-C3 pinout |
Watch out：
- Strapping pin: its level is latched at power-up to configure boot behaviour. Do not attach anything that changes its reset state.
Practical notes
Strapping pin with an internal weak pull-up (default value 1). Pulling it low at reset enters download mode — this is the BOOT button pin. When used as normal IO, add an external pull-up for stability.
Sample code
// Arduino
const int PIN = 9;
void setup() {
pinMode(PIN, OUTPUT);
}
void loop() {
digitalWrite(PIN, HIGH);
delay(500);
digitalWrite(PIN, LOW);
delay(500);
}
Data verified：2026-10-20 · Cross-checked against Espressif documentation. Always confirm against the official datasheet before finalizing a design. Official docs →