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Lion:Bit Dev Board
ESP32-based board designed for education and STEM - features built-in sensors and Grove connectors for quick prototyping.
ESP32
MCU
240MHz
clock
4MB
flash
520KB
SRAM
26· Two 12-bit, 18 Channels ADC
GPIO
BLE 4.2+ WiFi
radio
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 | strapping | - | |
| 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 | strapping | - | |
| 14 | 17 | D5PWM | strapping | - | |
| 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
10 pins with no boot or system involvementD11VSCKD10VMISOD6SDAD7SCLD9VMOSIDAC1PWMDAC2PWMCSPWMDCPWMRSTPWM
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 |
|---|---|---|---|
| LED_BUILTIN | GPIO0 | Must be HIGH during boot for normal startup; if held LOW on reset, forces flash programming mode. | Strapping |
| SWITCH_A | GPIO2 | If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure. | Strapping |
| SWITCH_B | GPIO4 | Sampled at reset for boot config; should not be driven at boot (affects boot mode timing). | Strapping |
| D8 | GPIO5 | Must be HIGH during boot; if pulled LOW at reset, alters SDIO slave timing and may prevent normal boot. | Strapping |
| MISO | MTDI (GPIO12) | Keep LOW during boot (internal PD); pulling HIGH at reset selects 1.8V flash mode, causing flash brownout if 3.3V flash is used. | Strapping |
| MOSI | MTCK (GPIO13) | Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed. | Other |
| SCK | MTMS (GPIO14) | Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot. | Other |
| SS | MTDO (GPIO15) | Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change. | Strapping |
| VP | GPIO36 (SENSOR_VP) | Cannot be used as output; only suitable for input (e.g., analog read). | Other |
| VN | GPIO39 (SENSOR_VN) | Cannot be used as output; only suitable for input. | Other |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| TX | U0TXD (GPIO1) | Connected to on-board USB-UART for uploading and logs; drives serial output at boot, so using as GPIO can disrupt programming or console. | USB |
| RX | U0RXD (GPIO3) | Used for receiving data from USB-UART (programming); also pulled HIGH at boot for console communication, so using as GPIO can disrupt uploads. | USB |
| D2 | GPIO9 (Flash SD2) | Used by internal flash/PSRAM; typically not exposed on modules, avoid using as GPIO. | Flash |
| D3 | GPIO10 (Flash SD3) | Used by internal flash/PSRAM; typically not exposed on modules, avoid using as GPIO. | Flash |
| D4 | GPIO16 | Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules. | Flash |
| D5 | GPIO17 | Connected to internal PSRAM on PSRAM-enabled modules; not usable as GPIO on those modules. | 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 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 (…
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.
10 of the exposed pins carry boot-time or system duties on the ESP32 (LED_BUILTIN, SWITCH_A, SWITCH_B and 7 more) - check the guidance above before wiring anything to them. D11, D10, D6, D7 and 6 more 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 GPIO18 - swap for your board's LED pin if different.
Board: Lion:bit Dev Board
Flash Size: 4MB · DIO
Upload Speed: 921600
// blink
pinMode(18, OUTPUT);
digitalWrite(18, LOW); // on (often inverted)[env:lionbit]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32:
board: esp32dev
variant: lionbit
framework:
type: esp-idf
# blink - GPIO18
output:
- platform: gpio
pin: 18
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesptool.py --chip esp32 --port /dev/ttyACM0 \
write_flash 0x0 firmware.binBuild details: sketch space 1310720 B · data 327680 B · DIO
Specifications
ESP32Compute
MCU
ESP32
Clock
240 MHz
SRAM · Flash
520 KB · 4MB
Radio
Wi-Fi
802.11 b/g/n
Bluetooth
4.2 LE
Antenna
PCB
I/O
GPIO · ADC
26 · Two 12-bit, 18 Channels
UART · I²C · SPI
3 · 2 · 4
PWM
16 channels
Power
USB
-
Serial
-
Boot address
0x1000
Display
Screen
TFT · 128x128
Driver
ST7735
Touch
No
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · DIO
Sketch · Data
1.25 MB · 320 KB
The Lion:Bit Dev Board 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
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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