Lion:Bit Dev Board

by Lion:Bit

ESP32-based board designed for education and STEM - features built-in sensors and Grove connectors for quick prototyping.

Pinout

ESP32

MCU

240MHz

clock

4MB

flash

520KB

SRAM

26· Two 12-bit, 18 Channels ADC

GPIO

BLE 4.2+ WiFi

radio

Pinout

27 pins

View:

Pin	GPIO	Labels	Status	Capabilities
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 involvement

D11VSCKD10VMISOD6SDAD7SCLD9VMOSIDAC1PWMDAC2PWMCSPWMDCPWMRSTPWM

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 minutes

Tool:

Connect over USB

Install your USB-serial driver (CH340 / CP210x) if no port appears. Not detected? Hold BOOT while plugging in.

Match & flash

Set the Tools options shown, then click Upload.

Verify it runs

The onboard LED on GPIO18 blinks - swap the pin if your board's LED differs.

Set these in Tools · leave everything else at default

Arduino IDE 2.x — Tools Copy

Board: "ESP32 Dev Module"▸

Flash Size: "4MB (32Mb)"▸

Flash Mode: "DIO"▸

Partition Scheme: "Default 4MB with spiffs (1.2MB APP / 1.5MB SPIFFS)" (default)▸

Upload Speed: "921600"▸

▸ every other Tools option — leave at default

Board: 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

Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32 Dev Module

blink.ino Copy

// blink the onboard LED
void setup() {
  pinMode(18, OUTPUT);
}
void loop() {
  digitalWrite(18, HIGH); delay(500);
  digitalWrite(18, LOW);  delay(500);
}

board to selectesp32dev⧉ copy

platformio.ini Copy

[env:lionbit]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600

Find it: PlatformIO Home ▸ Boards, search esp32dev — or type it after board =.

board to selectesp32dev⧉ copy

device.yaml Copy

esp32:
  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_out

Find it: search ESPHome's board list for esp32dev (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.

terminal Copy

esptool.py --chip esp32 --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 · DIO

Specifications

ESP32

Compute

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

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

ESP32 datasheet espressif.com↗ Lion:Bit Official Documentation lionbit.cc↗Lion:Bit Dev Board on PlatformIO docs.platformio.org↗Lion:Bit arduino-esp32 variant (pins_arduino.h) github.com↗

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