Waveshare 0.85″ ScreenKey Module — Reference
Canonical mechanical + electrical reference for Open Screen Deck.
Sources: Waveshare product page (SKU 34168), Waveshare docs, outline drawing (see below).
Our build SKU: 34168 — 0.85inch ScreenKey Module B (black keycap + switch + PCB)
Product variants
| SKU | Product |
|---|---|
| 34086 | ScreenKey LCD W (display + cap only) |
| 34087 | ScreenKey LCD B |
| 34167 | ScreenKey Module W (cap + switch + PCB) |
| 34168 | ScreenKey Module B ← use this |
In the box (34168):
- ScreenKey Module B host ×1
- MX1.25 9-pin 200 mm cable ×1
Weight: ~0.017 kg per module
Display & logic
| Parameter | Value |
|---|---|
| Panel | 0.85″ IPS |
| Resolution | 128 × 128 |
| Color | 65K (RGB565) |
| Driver IC | ST7735 |
| Interface | 4-wire SPI |
| Operating voltage | 3.3 V (5 V tolerant per docs — run at 3.3 V) |
| Visible display area | 15.21 × 15.21 mm |
| Pixel pitch | 118.8 × 118.8 µm |
Mechanical switch (Module W/B only)
| Parameter | Value |
|---|---|
| Actuation force | 50 ± 10 gf |
| Bottom-out force | 55 ± 10 gf |
| Actuation travel | 1.20 ± 0.30 mm |
| Total travel | 2.80 ± 0.25 mm |
| Spring length | 15.50 mm |
| Lifespan | 50 million cycles |
Outline dimensions (from Waveshare drawing)
Front (face toward user)
| Dimension | mm |
|---|---|
| Mounting hole centres (horizontal) | 22.00 |
| Mounting hole centres (vertical) | 25.30 |
| Visible LCD (square) | 15.21 × 15.21 |
Four corner mounting holes on this 22.00 × 25.30 mm pattern.
Back (PCB + connector)
| Dimension | mm |
|---|---|
| PCB width | 25.94 |
| PCB height | 35.29 |
9-pin header on PCB edge ( mates with included cable ).
Side (profile)
| Dimension | mm |
|---|---|
| Total stack height (cap tip → standoff bottom) | 24.00 |
| Keycap depth (cap only) | 8.60 |
Module includes rear brass standoffs — total height is not just the 8.6 mm cap; plan enclosure depth for ~24 mm or confirm standoffs are removed/shortened for our carrier design.
9-pin cable — SPI module interface
Connector on module: 9-pin 1.25 mm pitch (product cable: MX1.25).
Pin order per Waveshare docs (SPI control interface):
| Pin | Signal | Notes |
|---|---|---|
| 1 | KEY | Button, active level per firmware |
| 2 | DC | Data/command (Lo = cmd, Hi = data) |
| 3 | CS | Chip select, active low |
| 4 | SCLK | SPI clock |
| 5 | DIN | SPI MOSI |
| 6 | GND | |
| 7 | VCC | 3.3 V |
| 8 | PWM | Backlight (BL) |
| 9 | RST | Reset, active low |
Open Screen Deck GPIO map (carrier PCB)
| Module | CS | KEY |
|---|---|---|
| J1 | GPIO 10 | GPIO 38 |
| J2 | GPIO 1 | GPIO 39 |
| J3 | GPIO 2 | GPIO 40 |
| J4 | GPIO 3 | GPIO 41 |
| J5 | GPIO 4 | GPIO 42 |
| J6 | GPIO 5 | GPIO 47 |
Shared: dual SPI — J1–J3 use MOSI=11, SCK=12, DC=14; J4–J6 use MOSI=17, SCK=18, DC=8. Shared RST=21, BL(PWM)=13. microSD sits on bus A (CS=16, MISO=15). Canonical table: hardware/pinout.py.
CAD status
Rev E PCB + enclosure v14 aligned to the official vendor drawing (20.0 × 29.25 standoff pattern; dual SPI on the carrier).
Links
- Product: https://www.waveshare.com/0.85inch-screenkey.htm?sku=34168
- Wiki: https://docs.waveshare.com/0.85inch-ScreenKey-Module-W
- Resources: https://docs.waveshare.com/0.85inch-ScreenKey-Module-W/Resources-And-Documents
- Demo code: Waveshare GitHub / example packages linked from wiki