SPI with display modules in Raspberry Pi

Introduction

SPI helps the Raspberry Pi talk quickly to display screens. It sends pictures and text fast so you can see them right away.

You want to show sensor data on a small screen connected to your Raspberry Pi.

You are building a weather station and need to display temperature and humidity.

You want to create a simple game or clock on a tiny display.

You need a fast way to update graphics on a screen without delays.

Syntax

Raspberry Pi

import spidev

spi = spidev.SpiDev()
spi.open(bus, device)
spi.max_speed_hz = speed

spi.xfer2(data_bytes)

spi.close()

bus and device select the SPI channel on the Raspberry Pi.

xfer2() sends a list of bytes to the display and receives bytes back.

Examples

This example opens SPI bus 0, device 0, sets speed, sends a command byte to turn off the display, then closes SPI.

Raspberry Pi

import spidev

spi = spidev.SpiDev()
spi.open(0, 0)  # Use SPI bus 0, device 0
spi.max_speed_hz = 500000

spi.xfer2([0xAE])  # Send command to turn off the display

spi.close()

This sends a command byte followed by pixel data bytes to the display.

Raspberry Pi

import spidev

spi = spidev.SpiDev()
spi.open(0, 0)
spi.max_speed_hz = 1000000

# Send multiple bytes to draw pixels
spi.xfer2([0x40, 0xFF, 0x00, 0xFF])

spi.close()

Sample Program

This program opens SPI, sends commands to turn off the display, clears it by sending zeros, then turns it back on. It prints a message when done.

Raspberry Pi

import spidev
import time

spi = spidev.SpiDev()
spi.open(0, 0)  # SPI bus 0, device 0
spi.max_speed_hz = 800000

# Simple example: initialize display and clear screen
# Commands depend on your display module

# Turn display off
spi.xfer2([0xAE])
# Clear display (send zeros)
spi.xfer2([0x00] * 128)
# Turn display on
spi.xfer2([0xAF])

print("Display initialized and cleared.")

spi.close()

Important Notes

Always check your display's datasheet for the right command bytes.

Use proper wiring: connect MOSI, SCLK, CS, and power pins correctly.

Remember to close SPI after use to free the device.

Summary

SPI lets Raspberry Pi send commands and data fast to display modules.

Use spidev library to open SPI, send bytes, and close it.

Commands and data bytes depend on your specific display hardware.