Hello Nerves LCD SPI Example

Tiny Nerves demo that drives 320×480 SPI LCDs (ILI9486 / ST7796S) and optional touch (XPT2046 / GT911) on Raspberry Pi–class targets. The app shows build info, time, basic network status, and a demo image/text buffer.

Getting Started

# Pick your hardware target
export MIX_TARGET=rpi3      # or rpi4, etc.

# Pick your display variant (see table below)
export LCD_TYPE=c           # a | b | c | f | g   (defaults to a)

# Optional Wi-Fi
export NERVES_WIFI_SSID="your-ssid"
export NERVES_WIFI_PASSPHRASE="your-psk"

# Dependencies & firmware
mix deps.get
mix firmware

# Flash or upload
mix burn                    # SD card
./upload nerves.local       # OTA via ssh/mdns

• The firmware advertises via mDNS as nerves.local (plus the serial-based hostname).
• If you see “Image Nothing…”, place a 320×480 RGB565 file at priv/piyopiyoex_320x480.rgb565.

Display Types

Set LCD_TYPE to select panel + touch wiring/modules:

LCD_TYPE	Panel	LCD controller	Touch controller	Panel type
a	Waveshare 3.5" RPi LCD (A)	ILI9486	XPT2046	TFT
b	Waveshare 3.5" RPi LCD (B)	ILI9486	XPT2046	IPS
c	Waveshare 3.5" RPi LCD (C)	ILI9486	XPT2046	TFT
f	Waveshare 3.5" RPi LCD (F)	ST7796S	GT911	IPS
g	Waveshare 3.5" RPi LCD (G)	ST7796S	XPT2046	IPS

• MHS 3.5" is compatible with c-type wiring.

Pins and Buses (Raspberry Pi)

From the code defaults:

LCD ili9486(for A/B/C)(SPI over spidev0.0):

• SPI: spidev0.0
• DC: GPIO 24
• RST: GPIO 25
• BL (backlight enable): GPIO 18

LCD ST7796S(for F/G)(SPI over spidev0.0):

• SPI: spidev0.0
• DC: GPIO 22
• RST: GPIO 27
• BL (backlight enable): GPIO 18

Touch XPT2046 (for A/B/C/G):

• SPI: spidev0.1
• IRQ (pen-irq): GPIO 17

Touch GT911 (for F):

• I²C bus: i2c-1
• I²C addr: 0x14 (7-bit)
• INT: GPIO 4
• RST: GPIO 17

Adjust as needed if your hat uses different pins.

Hardware Targets

Nerves builds depend on MIX_TARGET. If it is unset, the project runs on the host for fast cycles and utility tasks.

Typical targets: rpi3, rpi4, rpi5.

See the full list of supported Nerves targets.

Configuration

Key environment variables:

• MIX_TARGET – Nerves system target (e.g., rpi3)
• LCD_TYPE – one of a|b|c|f|g (default a)
• NERVES_WIFI_SSID, NERVES_WIFI_PASSPHRASE – Wi-Fi credentials

Other notable config:

• regulatory_domain set to "JP" in config/target.exs
• SSH keys are required for shell/OTA (reads ~/.ssh/id_*.pub)