Hardware Assembly

Pin Connections

ESP32-C3 Super Mini Wiring

The ESP32-C3 requires 8 connections to the e-paper display:

E-Paper Pin	Function	ESP32-C3 Pin	GPIO	Wire Color Suggestion
BUSY	Busy Signal	A2	2	Yellow
CS	Chip Select	A3	3	Orange
SCK	SPI Clock	SCK	4	Green
SDI (MOSI)	SPI Data	MOSI	6	Blue
RES	Reset	SDA	8	Purple
DC	Data/Command	SCL	9	Gray
VCC (3.3V)	Power	3.3V	-	Red
GND	Ground	GND	-	Black

you can add 3 buttons for changing display modes manually

ESP32-C3 Super Mini          E-Paper Hat (DESPI-C02)
┌─────────────────┐         ┌─────────────────────────────┐
│                 │         │                             │
│ 3.3V      ●─────┼─────────┼─● VCC (3.3V)                │
│ GND       ●─────┼─────────┼─● GND                       │
│                 │         │                             │
│ GPIO 2    ●─────┼─────────┼─● BUSY                      │
│ GPIO 3    ●─────┼─────────┼─● CS                        │
│ GPIO 4    ●─────┼─────────┼─● SCK                       │
│ GPIO 6    ●─────┼─────────┼─● SDI (MOSI)                │
│ GPIO 8    ●─────┼─────────┼─● RES                       │
│ GPIO 9    ●─────┼─────────┼─● DC                        │
│                 │         │                             │
└─────────────────┘         └─────────────────────────────┘

TRMNL 7.5" (OG) DIY Kit Wiring (out of box)

The ESP32-S3 requires 8 connections to the e-paper display:

E-Paper Pin	Function	ESP32-S3 Pin	GPIO
BUSY	Busy Signal	GPIO 4	4
CS	Chip Select	GPIO 44	44
SCK	SPI Clock	GPIO 7	7
SDI (MOSI)	SPI Data	GPIO 9	9
RES	Reset	GPIO 38	38
DC	Data/Command	GPIO 10	10
VCC (3.3V)	Power	3.3V	-
GND	Ground	GND	-

Button Function	ESP32-S3 GPIO	Connection
Half & Half Mode	GPIO 2	Button → GND
Weather Only Mode	GPIO 3	Button → GND
Departure Only Mode	GPIO 5	Button → GND

💡 Tip: Use momentary push buttons (normally open)

Battery Connection

1. Identify battery connector

   • Most ESP32 boards have a JST connector for LiPo batteries
   • Check polarity: Red (+), Black (-)

2. Connect battery

   • ⚠️ IMPORTANT: Verify polarity before connecting!
   • Wrong polarity can damage the board
   • Match red to red, black to black

3. Test with multimeter first

   • Check battery voltage: should be 3.7-4.2V
   • Verify polarity matches board connector

Safety Notes

⚠️ Important Safety Information:

• LiPo Battery Safety:

  • Never short circuit battery terminals
  • Don't puncture or damage battery
  • Charge at appropriate rate (1C max)
  • Monitor temperature during charging
  • Store at 50-60% charge if not using

• Soldering Safety:

  • Use in well-ventilated area
  • Don't touch hot iron tip
  • Use proper ventilation/fume extraction
  • Wash hands after handling solder

• Electrical Safety:

  • Disconnect power before making connections
  • Verify polarity before connecting battery
  • Don't exceed voltage ratings (3.3V for display)