Lion:Bit Dev Board
ESP32-based board designed for education and STEM - features built-in sensors and Grove connectors for quick prototyping.
Lion:Bit Dev Board Pinout
27 pins| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | LED_BUILTIN | strapping | - | |
| 2 | 1 | TXD1PWM | uart | uart | |
| 3 | 2 | SWITCH_APWM | strapping | - | |
| 4 | 3 | RXD0PWM | uart | uart | |
| 5 | 4 | SWITCH_BPWM | safe | - | |
| 6 | 5 | D8VSSPWM | strapping | - | |
| 7 | 9 | D2U1RXPWM | strapping | - | |
| 8 | 10 | D3U1TXPWM | strapping | - | |
| 9 | 12 | MISOMTDIPWM | strapping | spi | |
| 10 | 13 | MOSIMTCKPWM | strapping | spi | |
| 11 | 14 | SCKMTMSPWM | strapping | spi | |
| 12 | 15 | SSMTDOPWM | strapping | spi | |
| 13 | 16 | D4PWM | safe | - | |
| 14 | 17 | D5PWM | safe | - | |
| 15 | 18 | D11VSCKCLKPWM | safe | - | |
| 16 | 19 | D10VMISOPWM | safe | - | |
| 17 | 21 | D6SDAPWM | safe | i2c | |
| 18 | 22 | D7SCLPWM | safe | i2c | |
| 19 | 23 | D9VMOSIST_MOSIPWM | safe | - | |
| 20 | 25 | DAC1PWM | safe | dac | |
| 21 | 26 | DAC2PWM | safe | dac | |
| 22 | 27 | CSPWM | safe | - | |
| 23 | 32 | DCPWM | safe | - | |
| 24 | 33 | RSTPWM | safe | - | |
| 25 | 36 | VPT0 | strapping | touch | |
| 26 | 39 | VNT1 | strapping | touch | |
| 27 | - | A0A1A2A3A4A5 | safe | adc |
Start with these
13 pins with no boot or system involvementFreely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
11 pins · 11 things to knowLED_BUILTINGPIO0 Bootstrapping pin (enter bootloader when low); internal pull-up. Strapping
Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode.
TXGPIO1 Default UART0 TX pin for USB-serial programming and console. UART
Connected to on-board USB-UART for uploading and logs; drives serial output at boot, so using as GPIO can disrupt programming or console.
SWITCH_AGPIO2 Bootstrapping pin (must be low or floating at reset); internal pull-down. Strapping
If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure.
RXGPIO3 Default UART0 RX pin for USB-serial programming (console input). UART
Used for receiving data from USB-UART (programming); also pulled HIGH at boot for console communication, so using as GPIO can disrupt uploads.
D8GPIO5 Bootstrapping pin; internal pull-up; VSPI CS0 (default SPI chip-select); acts as FSPIWP (flash write-protect) on internal-flash variants. Strapping
Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot.
MISOGPIO12 Bootstrapping pin; JTAG TDI; sets flash voltage (VDD_SDIO); also HSPIQ (flash data line). Strapping
Keep LOW during boot (internal PD); pulling HIGH at reset selects 1.8V flash mode, causing flash brownout if 3.3V flash is used.
MOSIGPIO13 JTAG clock pin (TCK); also ADC2 channel 4 / Touch4 input. JTAG
Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed.
SCKGPIO14 JTAG mode select pin (TMS); also HSPI CLK and PWM-capable GPIO. JTAG
Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot.
SSGPIO15 Bootstrapping pin; JTAG TDO; controls UART0 boot log output; also HSPICS0 (secondary SPI CS). Strapping
Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change.
VPGPIO36 Input-only GPIO (no output); ADC1 channel 0, Hall sensor VP. Other
Cannot be used as output; only suitable for input (e.g., analog read).
VNGPIO39 Input-only GPIO (no output); ADC1 channel 3, Hall sensor VN. Other
Cannot be used as output; only suitable for input.
Only if you know the tricks
2 pins · 1 thing to knowD2GPIO9D3GPIO10 SPI flash/PSRAM data lines SD2 and SD3 (flash HOLD and WP) Flash
Used by internal flash/PSRAM; typically not exposed on modules, avoid using as GPIO.
- D2Connected to SPI flash/PSRAM data 2 (SD2, flash HOLD).
- D3Connected to SPI flash/PSRAM data 3 (SD3, flash WP).
Across 27 pins, the Lion:Bit Dev Board exposes 26 GPIO.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO21 and SCL on GPIO22; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO1 and GPIO3 cover serial logging and flashing.
Beyond plain digital I/O you get 2 capacitive-touch inputs and 2 true DAC outputs.
11 of the exposed pins carry boot-time or system duties on the ESP32 (LED_BUILTIN, TX, SWITCH_A and 8 more) - check the guidance above before wiring anything to them. SWITCH_B, D4, D5, D11 and 9 more are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutesBoard: ESP32 Dev Module Flash Size: 4MB (32Mb) Flash Mode: DIO Partition Scheme: Default 4MB with spiffs (1.2MB APP/1.5MB SPIFFS) Upload Speed: 921600
// toggle GPIO4 - wire an LED and resistor to it
void setup() {
pinMode(4, OUTPUT);
}
void loop() {
digitalWrite(4, HIGH); delay(500);
digitalWrite(4, LOW); delay(500);
}[env:lionbit]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32dev - or type it after board =.esp32:
board: esp32dev
variant: esp32
framework:
type: esp-idf
# blink - GPIO4
output:
- platform: gpio
pin: 4
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesp32dev (same ids as PlatformIO).esptool.py --chip esp32 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x1000 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Specifications
ESP32 · vs other ESP32 chips →About this board
Inside sits the ESP32 - a dual-core Xtensa with both Bluetooth Classic and BLE.
Around the module: a TFT 128x128 display, a Grove connector, a buzzer, an ambient-light sensor, status LEDs (RGB) and A/B buttons.
Resources
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