Wiring & Pinout¶

GPIO assignments and breadboard wiring for the Dilder test bench.

Full official hardware reference docs:

Display Wiring (HAT — no jumpers needed)¶

The Waveshare 2.13" e-Paper HAT plugs directly onto the Pi Zero's 40-pin GPIO header. No jumper wires are needed for the display.

HAT = Header Attachment

Align pin 1 on the HAT with pin 1 on the Pi (the corner nearest the SD card slot), press down firmly until the HAT sits flush. Always power off the Pi before attaching or removing it.

Display Pin Mapping¶

Sourced from the Waveshare official reference.

e-Paper Signal	Function	BCM GPIO	Physical Pin	Direction
VCC	3.3V power	3.3V rail	1	→ display
GND	Ground	GND	6	→ display
DIN	SPI MOSI — pixel data	GPIO 10	19	→ display
CLK	SPI clock	GPIO 11	23	→ display
CS	Chip select (active LOW)	GPIO 8 (CE0)	24	→ display
DC	Data / command select	GPIO 25	22	→ display
RST	Reset (active LOW)	GPIO 17	11	→ display
BUSY	Busy flag (HIGH = refreshing)	GPIO 24	18	← display

Signal Quick Reference¶

Signal	When HIGH	When LOW
CS	Display deselected	Display active
DC	Sending pixel data	Sending command byte
RST	Normal operation	Hardware reset
BUSY	Display refreshing — wait	Ready for commands

Button Wiring (Breadboard)¶

Five 6×6mm tactile buttons wired to GPIO pins using the Pi's internal pull-up resistors. No external resistors needed.

Per-button wiring:

Pi GPIO pin ──── button leg A
                 button leg B ──── GND rail

When the button is pressed it pulls the GPIO line LOW → software reads as pressed.

Button GPIO Assignments¶

Sourced from the Pi Zero WH GPIO reference — pins chosen to avoid SPI, I²C, UART, and PWM conflicts.

Button	BCM GPIO	Physical Pin	Internal pull-up
Up	GPIO 5	29	Enabled in software
Down	GPIO 6	31	Enabled in software
Left	GPIO 13	33	Enabled in software
Right	GPIO 19	35	Enabled in software
Center / Select	GPIO 26	37	Enabled in software

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)

BUTTONS = {
    'up':     5,
    'down':   6,
    'left':   13,
    'right':  19,
    'center': 26,
}

for pin in BUTTONS.values():
    GPIO.setup(pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)

Full GPIO Pin Budget¶

Function	BCM GPIO	Physical Pin	Interface
e-ink VCC	3.3V	1	Power
e-ink GND	GND	6	Ground
e-ink DIN	GPIO 10	19	SPI MOSI
e-ink CLK	GPIO 11	23	SPI SCLK
e-ink CS	GPIO 8	24	SPI CE0
e-ink DC	GPIO 25	22	Digital out
e-ink RST	GPIO 17	11	Digital out
e-ink BUSY	GPIO 24	18	Digital in
Button UP	GPIO 5	29	Digital in
Button DOWN	GPIO 6	31	Digital in
Button LEFT	GPIO 13	33	Digital in
Button RIGHT	GPIO 19	35	Digital in
Button CENTER	GPIO 26	37	Digital in
Piezo buzzer (future)	GPIO 12 or 18	32 / 12	PWM
Pins used	13
Pins free	13+ general GPIO remaining

Complete 40-Pin Header Map¶

Pins used by this project are highlighted. Full electrical specs in the Pi Zero WH reference.

       3V3  [ 1] [ 2]  5V
     GPIO2  [ 3] [ 4]  5V
     GPIO3  [ 5] [ 6]  GND
     GPIO4  [ 7] [ 8]  GPIO14
       GND  [ 9] [10]  GPIO15
▶  GPIO17  [11] [12]  GPIO18      RST  (e-ink)
    GPIO27  [13] [14]  GND
    GPIO22  [15] [16]  GPIO23
       3V3  [17] [18]  GPIO24 ◀   BUSY (e-ink)
▶  GPIO10  [19] [20]  GND         DIN  (e-ink)
     GPIO9  [21] [22]  GPIO25 ▶   DC   (e-ink)
▶  GPIO11  [23] [24]  GPIO8  ▶   CLK / CS (e-ink)
       GND  [25] [26]  GPIO7
     GPIO0  [27] [28]  GPIO1
▶   GPIO5  [29] [30]  GND         UP   (button)
▶   GPIO6  [31] [32]  GPIO12
▶  GPIO13  [33] [34]  GND         LEFT (button)
▶  GPIO19  [35] [36]  GPIO16      RIGHT (button)
▶  GPIO26  [37] [38]  GPIO20      CENTER (button)
       GND  [39] [40]  GPIO21
                                   DOWN = GPIO6 (pin 31)
▶ = used by Dilder

Wiring Diagram (Text)¶

Pi Zero WH
│
├─ Pin 1  (3.3V) ──────────────── HAT VCC
├─ Pin 6  (GND)  ──────────────── HAT GND ── breadboard GND rail
├─ Pin 19 (GPIO10 / MOSI) ─────── HAT DIN
├─ Pin 23 (GPIO11 / SCLK) ─────── HAT CLK
├─ Pin 24 (GPIO8  / CE0)  ─────── HAT CS
├─ Pin 22 (GPIO25) ────────────── HAT DC
├─ Pin 11 (GPIO17) ────────────── HAT RST
├─ Pin 18 (GPIO24) ────────────── HAT BUSY
│
├─ Pin 29 (GPIO5)  ─── [BTN UP]     ─── GND
├─ Pin 31 (GPIO6)  ─── [BTN DOWN]   ─── GND
├─ Pin 33 (GPIO13) ─── [BTN LEFT]   ─── GND
├─ Pin 35 (GPIO19) ─── [BTN RIGHT]  ─── GND
└─ Pin 37 (GPIO26) ─── [BTN CENTER] ─── GND

SPI Configuration¶

The e-ink display requires SPI to be enabled before use. See Pi Zero Setup for instructions.

SPI Parameter	Value
Bus	SPI0 (`/dev/spidev0.0`)
Mode	Mode 0 (CPOL=0, CPHA=0)
Bit order	MSB first
Clock speed	4 MHz (typical)
CS signal	Active LOW

Verify SPI is active after enabling:

ls /dev/spi*
# Expected: /dev/spidev0.0   /dev/spidev0.1

Troubleshooting¶

Symptom	Check
Display shows nothing	SPI enabled? Run `ls /dev/spi*`
Garbage output	Wrong driver version (V3 vs V4) — check PCB silkscreen
Permission error on `/dev/spidev`	Add user to `spi` group: `sudo usermod -aG spi,gpio pi`
BUSY pin always HIGH	Display stuck in refresh — power cycle and run `epd.Clear()`
Button reads always HIGH	`GPIO.PUD_UP` not set, or button not connected to GND
Button reads always LOW	Short to ground — check breadboard wiring