MONSTER M4SK - DIY Electronic Eyes Mask

Wearable mask board with two 240x240 IPS TFT displays driven by a 120 MHz ARM Cortex-M4. Runs animated eye graphics without a full Linux computer.

Logical pinout · physical placement not verified

USB Micro
USB Micro port used for powering and programming the MONSTER M4SK board.
Type · Power
JST 2-PH battery
3.7/4.2V LiPoly battery port; battery can recharge over the Micro USB jack.
Type · PowerVoltage · 3.7/4.2V LiPoly battery, source-stated
Headphone leftA0
Stereo headphone jack channel connected to SAMD51 analog DAC pin A0.
Type · GPIO, Analog
Headphone rightA1
Stereo headphone jack channel connected to SAMD51 analog DAC pin A1.
Type · GPIO, Analog
SpeakerA0
Molex PicoBlade mono speaker connector for smaller 8 ohm 1W speakers; speaker signal connected to A0 analog DAC.
Type · GPIO, Analog
Speaker enablepin 20
Enables or disables the mono speaker driver.
Type · Control
PDM microphone port
4-pin JST SH port for optional PDM microphone; connected to SERCOM pins and read using SPI2 for PDM data.
Type · Signal
D2Capacitive touch nose
Front capacitive touch pad nose connected to D2; usable as an input.
Type · GPIO, Signal
Button 1seesaw pin 9
Tactile button connected to the seesaw chip on pin 9; button connects to ground when pressed.
Type · Unknown
Button 2seesaw pin 10
Tactile button connected to the seesaw chip on pin 10; button connects to ground when pressed.
Type · Unknown
Button 3seesaw pin 11
Tactile button connected to the seesaw chip on pin 11; button connects to ground when pressed.
Type · Unknown
Light sensorseesaw pin 1
Reverse-mount light sensor connected to the seesaw chip on pin 1; read as an analog value.
Type · Unknown
STEMMAGrove SCL
4-pin JST I2C connector clock line, shared with the seesaw chip and accelerometer; usable as board.SCL or board.STEMMA_I2C().
Type · I2CVoltage · Connector defaults to 5V; solder/cut jumper can change it between 5V and 3V, source-stated
STEMMAGrove SDA
4-pin JST I2C connector data line, shared with the seesaw chip and accelerometer; usable as board.SDA or board.STEMMA_I2C().
Type · I2CVoltage · Connector defaults to 5V; solder/cut jumper can change it between 5V and 3V, source-stated
D2 JST signal
3-pin JST digital/analog connector signal; can be analog input or digital I/O, exposed as board.D2 or Arduino digital 2 and analog A2.
Type · GPIO
D3 JST signal
3-pin JST digital/analog connector signal; can be analog input or digital I/O, exposed as board.D3 or Arduino digital 3 and analog A3.
Type · GPIO
Reset button
Reset button restarts firmware with one click and enters bootloader mode with two clicks.
Type · Control
D13Red LED
Little red LED tied to pin D13; controllable in code and pulses in bootloader mode.
Type · GPIO, Unknown
9-pin JST SH interconnect
Inside-edge 9-pin JST SH connector lets the two PCB halves be separated and bridged with a 9-pin cable.
Type · Unknown

Pin	Type	Function	Voltage
USB Micro	Power	USB Micro port used for powering and programming the MONSTER M4SK board.
JST 2-PH battery	Power	3.7/4.2V LiPoly battery port; battery can recharge over the Micro USB jack.	3.7/4.2V LiPoly battery, source-stated
Headphone leftA0	GPIO, Analog	Stereo headphone jack channel connected to SAMD51 analog DAC pin A0.
Headphone rightA1	GPIO, Analog	Stereo headphone jack channel connected to SAMD51 analog DAC pin A1.
SpeakerA0	GPIO, Analog	Molex PicoBlade mono speaker connector for smaller 8 ohm 1W speakers; speaker signal connected to A0 analog DAC.
Speaker enablepin 20	Control	Enables or disables the mono speaker driver.
PDM microphone port	Signal	4-pin JST SH port for optional PDM microphone; connected to SERCOM pins and read using SPI2 for PDM data.
D2Capacitive touch nose	GPIO, Signal	Front capacitive touch pad nose connected to D2; usable as an input.
Button 1seesaw pin 9	Unknown	Tactile button connected to the seesaw chip on pin 9; button connects to ground when pressed.
Button 2seesaw pin 10	Unknown	Tactile button connected to the seesaw chip on pin 10; button connects to ground when pressed.
Button 3seesaw pin 11	Unknown	Tactile button connected to the seesaw chip on pin 11; button connects to ground when pressed.
Light sensorseesaw pin 1	Unknown	Reverse-mount light sensor connected to the seesaw chip on pin 1; read as an analog value.
STEMMAGrove SCL	I2C	4-pin JST I2C connector clock line, shared with the seesaw chip and accelerometer; usable as board.SCL or board.STEMMA_I2C().	Connector defaults to 5V; solder/cut jumper can change it between 5V and 3V, source-stated
STEMMAGrove SDA	I2C	4-pin JST I2C connector data line, shared with the seesaw chip and accelerometer; usable as board.SDA or board.STEMMA_I2C().	Connector defaults to 5V; solder/cut jumper can change it between 5V and 3V, source-stated
D2 JST signal	GPIO	3-pin JST digital/analog connector signal; can be analog input or digital I/O, exposed as board.D2 or Arduino digital 2 and analog A2.
D3 JST signal	GPIO	3-pin JST digital/analog connector signal; can be analog input or digital I/O, exposed as board.D3 or Arduino digital 3 and analog A3.
Reset button	Control	Reset button restarts firmware with one click and enters bootloader mode with two clicks.
D13Red LED	GPIO, Unknown	Little red LED tied to pin D13; controllable in code and pulses in bootloader mode.
9-pin JST SH interconnect	Unknown	Inside-edge 9-pin JST SH connector lets the two PCB halves be separated and bridged with a 9-pin cable.

Logical pinout · physical placement not verified

Pin details

19 connections

USB Micro
USB Micro port used for powering and programming the MONSTER M4SK board.
Power
JST 2-PH battery
3.7/4.2V LiPoly battery port; battery can recharge over the Micro USB jack.
PowerVoltage · 3.7/4.2V LiPoly battery, source-stated
Headphone leftA0
Stereo headphone jack channel connected to SAMD51 analog DAC pin A0.
GPIO, Analog
Headphone rightA1
Stereo headphone jack channel connected to SAMD51 analog DAC pin A1.
GPIO, Analog
SpeakerA0
Molex PicoBlade mono speaker connector for smaller 8 ohm 1W speakers; speaker signal connected to A0 analog DAC.
GPIO, Analog
Speaker enablepin 20
Enables or disables the mono speaker driver.
Control
PDM microphone port
4-pin JST SH port for optional PDM microphone; connected to SERCOM pins and read using SPI2 for PDM data.
Signal
D2Capacitive touch nose
Front capacitive touch pad nose connected to D2; usable as an input.
GPIO, Signal
Button 1seesaw pin 9
Tactile button connected to the seesaw chip on pin 9; button connects to ground when pressed.
Unknown
Button 2seesaw pin 10
Tactile button connected to the seesaw chip on pin 10; button connects to ground when pressed.
Unknown
Button 3seesaw pin 11
Tactile button connected to the seesaw chip on pin 11; button connects to ground when pressed.
Unknown
Light sensorseesaw pin 1
Reverse-mount light sensor connected to the seesaw chip on pin 1; read as an analog value.
Unknown
STEMMAGrove SCL
4-pin JST I2C connector clock line, shared with the seesaw chip and accelerometer; usable as board.SCL or board.STEMMA_I2C().
I2CVoltage · Connector defaults to 5V; solder/cut jumper can change it between 5V and 3V, source-stated
STEMMAGrove SDA
4-pin JST I2C connector data line, shared with the seesaw chip and accelerometer; usable as board.SDA or board.STEMMA_I2C().
I2CVoltage · Connector defaults to 5V; solder/cut jumper can change it between 5V and 3V, source-stated
D2 JST signal
3-pin JST digital/analog connector signal; can be analog input or digital I/O, exposed as board.D2 or Arduino digital 2 and analog A2.
GPIO
D3 JST signal
3-pin JST digital/analog connector signal; can be analog input or digital I/O, exposed as board.D3 or Arduino digital 3 and analog A3.
GPIO
Reset button
Reset button restarts firmware with one click and enters bootloader mode with two clicks.
Control
D13Red LED
Little red LED tied to pin D13; controllable in code and pulses in bootloader mode.
GPIO, Unknown
9-pin JST SH interconnect
Inside-edge 9-pin JST SH connector lets the two PCB halves be separated and bridged with a 9-pin cable.
Unknown

Start wiring

USB · 3.3 V

Confirm the data interface matches your host board.

Module pins: JST 2-PH battery, PDM microphone port, Capacitive touch nose / D2, STEMMA/Grove SCL, STEMMA/Grove SDA, D2 JST signal, D3 JST signal. Schematik maps them to your board in the app.

Other MCUs

228 other options

Specialists: Teensy for high-clock audio and USB, Adafruit SAMD boards running CircuitPython or the Arduino IDE, proper STM32 eval kits, and the micro:bit classroom ecosystem. Schematik builds target ESP32, Arduino Uno, and Pico; come here when you have a specific reason to.

View all 228

Related groups

4 groups

Arduino

About 75 boards across every Arduino generation: 5V Uno/Mega/GIGA, 3.3V MKR and Portenta, plus DFRduino and Bluno compatibles. Confirm the voltage rail before stacking any shield.

Boards · Arduino boards · 77 parts

ESP32

Wi-Fi and Bluetooth on a single chip, in every shape from Espressif DevKitC to Adafruit Feathers with STEMMA QT, DFRobot FireBeetles tuned for battery life, and Seeed XIAOs under a thumbnail.

Boards · ESP32 boards · 159 parts

Add-ons

About 270 add-ons across Pi HATs, Arduino shields, and FeatherWings. The same function — motor control, PoE, display — usually ships once per host connector family. Get the host board right first.

Boards · HATs, Shields & add-ons · 270 parts

Pi Pico

The Raspberry Pi MCU line — Pico, Pico 2, and third-party boards on the same silicon — plus a deep bench of Pico-pinout displays, loggers, and radio modules that do nothing without a Pico plugged in.

Boards · Pico & RP2040 boards · 43 parts