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TTGO T-OI PLUS RISC-V ESP32-C3
LilyGO’s ESP32-C3 board with RISC-V core and USB-C - great for portable, low-cost IoT projects with BLE and Wi-Fi.
45.7 × 25.8 mm
ESP32-C3
RISC-V MCU
160MHz
clock
4MB
flash
400KB
SRAM
10· 3 ADC
GPIO
BLE 5.0+ WiFi
radio
Pinout
10 pins · 2.54 mm pitch
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 2 | A1BAT_ADC_PIN | strapping | adc | |
| 2 | 3 | LED_BUILTIN | safe | - | |
| 3 | 4 | SCKA2 | strapping | adc · spi | |
| 4 | 5 | MISOA3 | strapping | adc · spi | |
| 5 | 6 | MOSI | strapping | spi | |
| 6 | 7 | SS | strapping | spi | |
| 7 | 18 | SCL | uart | i2c | |
| 8 | 19 | SDA | uart | i2c | |
| 9 | 20 | RX | uart | uart | |
| 10 | 21 | TX | uart | uart |
Start with these
1 pins with no boot or system involvementLED_BUILTIN
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 |
|---|---|---|---|
| A1 | 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 |
| 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 |
|---|---|---|---|
| SCL | USB_D- | By default connected to on-chip USB Serial/JTAG controller; to use as GPIO it must be reconfigured from its USB function | USB |
| SDA | USB_D+ | By default connected to on-chip USB Serial/JTAG controller; not available for GPIO use unless USB functionality is disabled or remapped | USB |
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 10 pins on the TTGO T-OI PLUS RISC-V ESP32-C3 are usable GPIO, spaced at the standard 2.54 mm pitch. Peripheral wiring is straightforward: I²C is mapped to…
All 10 pins on the TTGO T-OI PLUS RISC-V ESP32-C3 are usable GPIO, spaced at the standard 2.54 mm pitch.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO19 and SCL on GPIO18; 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 3 ADC-capable pins for sensors and battery monitoring.
7 of the exposed pins carry boot-time or system duties on the ESP32-C3 (A1, SCK, MISO and 4 more) - check the guidance above before wiring anything to them. LED_BUILTIN is free of any such role - the safest first picks.
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
GPIO3 toggles - wire an LED and resistor to it, or change the pin to your board's own LED.
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: "QIO"▸
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: QIO Partition Scheme: Default 4MB with spiffs (1.2MB APP/1.5MB SPIFFS) Upload Speed: 921600
Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32C3 Dev Module
// toggle GPIO3 - wire an LED and resistor to it
void setup() {
pinMode(3, OUTPUT);
}
void loop() {
digitalWrite(3, HIGH); delay(500);
digitalWrite(3, LOW); delay(500);
}board to selectesp32-c3-devkitm-1⧉ copy
[env:ttgo-t-oi-plus]
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: esp32c3
framework:
type: esp-idf
# blink - GPIO3
output:
- platform: gpio
pin: 3
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 · QIO
Specifications
ESP32-C3 · 45.7 × 25.8 mm · vs other ESP32 chips →Compute
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
Ceramic
I/O
GPIO · ADC
10 · 3
UART · I²C · SPI
2 · 1 · 1
PWM
6 channels
Power
USB
USB-C
Serial
CH340K
Boot address
0x0
Electrical
Input
5V USB · 3.7V 16340 Li-ion
Consumption
-
Regulator
ME6211
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
QIO · QIO
Sketch · Data
1.25 MB · 320 KB
45.7 × 25.8 mm · pin pitch 2.54 mm
The TTGO T-OI PLUS RISC-V ESP32-C3 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.
At $5.50 it's cheaper than most ESP32-C3 boards, which usually run around $10.
Only 10 GPIO are broken out, where most ESP32-C3 boards manage about 13 - worth checking the pinout covers what you need.
Around the module: a Grove connector, battery charging (TP4054), status LEDs (Power, Charge, UART) and Reset buttons.
- Rechargeable 16340 Li-ion battery holder on the back
- TP4054 Li-ion charger without on-board battery protection (use protected cells)
- IPEX/u.FL connector for an external antenna
- Power ON/OFF slide switch
- D1 mini-compatible pinout
Where to buy
prices are typical street pricesTTGO T-OI PLUS RISC-V ESP32-C3
$5.50per unit, typical
Resources
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