3.5 inch TFT touchscreen for Raspberry Pi: specs and pinout
Reference: Waveshare 3.5inch RPi LCD (A); the stocked clone may differ. A 3.5 inch 480 x 320 resistive-touch TFT that plugs onto the 40-pin Raspberry Pi header and is driven over SPI. Facts here come from the Waveshare 3.5inch RPi LCD (A) wiki; the stocked board's maker is not confirmed.
Specs
| Spec | Value | Source |
|---|---|---|
| Resolution (Waveshare (A) reference) | 480 x 320 | source Features |
| Touch (Waveshare (A) reference) | Resistive touch control | source Features |
| Connector (Waveshare (A) reference) | 26-pin connector onto the Raspberry Pi 40-pin GPIO header; plugs directly onto the Pi | source Hardware Connection |
| Supply (Waveshare (A) reference) | 3.3 V and 5 V power inputs on the header | source Pinout Definition (pins 1, 2, 4, 17) |
| Normal operating current (Waveshare (A) figure) | about 150 mA (Waveshare figure; stocked board may differ) | source FAQ |
| Operating temperature (Waveshare (A) figure) | 0 to 70 C commercial grade (Waveshare figure; stocked board may differ) | source FAQ |
| Compatibility (Waveshare (A) figure) | Waveshare states: compatible with any version of Raspberry Pi, same size as a Raspberry Pi 3 / 4 / 5; not confirmed for the stocked board | source Features |
Power
| Value | Source | |
|---|---|---|
| Supply | 3.3 V and 5 V from the Pi header (Waveshare (A) reference layout) | source Pinout Definition; FAQ |
| Current | about 150 mA (Waveshare (A) figure; stocked board may differ) | source Pinout Definition; FAQ |
Pinout
Reference: Waveshare 3.5inch RPi LCD (A); the stocked clone may differ. Pin rows below are from that pin table. Pins the wiki marks NC (3, 5, 7, 8, 10, 12, 13, 15, 16) are not used by that screen, but whether they are reachable while the screen sits on the header, and whether the stocked board leaves them free, is not confirmed.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 1 | 3.3V | 3.3 V | Power positive | source Pinout Definition table |
| 2 | 5V | 5 V | Power positive | source Pinout Definition table |
| 4 | 5V | 5 V | Power positive | source Pinout Definition table |
| 6 | GND | 0 V | Ground | source Pinout Definition table |
| 9 | GND | 0 V | Ground | source Pinout Definition table |
| 11 | TP_IRQ | Touch panel interrupt, low when the panel is pressed | source Pinout Definition table | |
| 14 | GND | 0 V | Ground | source Pinout Definition table |
| 17 | 3.3V | 3.3 V | Power positive | source Pinout Definition table |
| 18 | LCD_RS | Command / data register selection | source Pinout Definition table | |
| 19 | LCD_SI / TP_SI | LCD display / SPI data input of touch panel | source Pinout Definition table | |
| 20 | GND | 0 V | Ground | source Pinout Definition table |
| 21 | TP_SCL | SPI data output of touch panel | source Pinout Definition table | |
| 22 | RST | Reset | source Pinout Definition table | |
| 23 | LCD_SCK / TP_SCK | LCD display / SPI clock signal of touch panel | source Pinout Definition table | |
| 24 | LCD_CS | LCD chip select, low level selects LCD | source Pinout Definition table | |
| 25 | GND | 0 V | Ground | source Pinout Definition table |
| 26 | TP_CS | Touch panel chip select, low level selects the touch panel | source Pinout Definition table |
Build with it
Project ideas for the 3.5 inch TFT touchscreen for Raspberry Pi. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.
- Pi temperature dashboard: If the stocked screen's header leaves pin 7 free (the Waveshare (A) wiki marks it NC), tap it with a header extension or stacking header; a screen sitting on the header covers the pins. The DS18B20 is a digital one-wire sensor, so the Pi needs no analog input. It needs a 4.7 k pull-up between data and 3.3 V: the resistor pack's values are not listed, so take the 4.7 k (yellow, violet, red bands) if it is there, otherwise wire the stocked 10 k potentiometer as a variable resistor and set it to 4.7 k with the multimeter before connecting. Learning project.
- Touch clock: If the stocked screen's header leaves pins 3 and 5 free (the Waveshare (A) wiki marks them NC), reach the I2C pins with a header extension or stacking header. The screen itself uses 3.3 V pins 1 and 17, so there is no spare 3.3 V pin; take 3.3 V from pin 1 or 17 through the same stacking header (they are the same Pi 3.3 V rail, so the clock module shares the screen's supply) and GND from a pin that passes through the same way. The wiki does not document how much 3.3 V current the screen draws, so keep the clock module's load small; check this on your board first. Learning project.
- Camera preview screen: Fine for a desk or workshop viewer; tell anyone in view that a camera is on. Use the supply recommended for your Pi model.
Common mistakes
- Powering the Pi from a weak source: Waveshare recommends a 5 V 2.5 A adapter for its own board with a Pi, and a PC USB port may not boot the Pi with the screen attached; use the supply recommended for your Pi model (source), Software Settings note)
- Running apt upgrade and losing the display: the wiki says this can make the LCD malfunction, and the fix is to delete the dtoverlay=ads7846 line in config.txt (source), Note 1 under Software Settings)
- Misaligning the connector: the screen has 26 pins but the Pi has 40, so the wiki says to check which screen pins meet which Pi pins (source), Hardware Connection)
Not covered by the official source
- The stocked board's maker is not confirmed; the Waveshare (A) wiki is the reference layout only, and clone boards can differ in controller and touch IC.
- The wiki does not name the display or touch controller chips, so none are listed.
- BCM GPIO numbers for the SPI pins are not given here.
- Spec rows and pin table are the Waveshare (A) reference; current, temperature range, touch IC and which header pins are free can differ on a clone.
Sources
- link) (Waveshare wiki, 3.5inch RPi LCD (A))