ST7789/CST7789 display only showing backlight with Raspberry Pi Pico 2
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I’m trying to connect a 1.3” 240x240 SPI TFT display labeled “CST7789” to a Raspberry Pi Pico 2 using MicroPython.
The display backlight turns on, but the screen itself never changes or displays anything.
What I’ve tested so far:
.Pico works correctly
.onboard LED test works
.SPI commands are being sent without errors
.reset and DC pins are toggling correctly
.I once saw a brief flicker on the display during testing
Current wiring:
SCL -> GP18
SDA -> GP19
RES -> GP20
DC -> GP21
VCC -> 3.3V
GND -> GND
BLK -> 3.3V
The module does NOT have a CS pin.
I’ve tried:
.swapping SCL/SDA
.lowering SPI baudrate massively
.multiple initialization sequences
.checking breadboard connections
Current test code:
from machine import Pin, SPI
import time
spi = SPI(
0,
baudrate=10000,
polarity=0,
phase=0,
sck=Pin(18),
mosi=Pin(19)
)
dc = Pin(21, Pin.OUT)
rst = Pin(20, Pin.OUT)
def cmd(c):
dc.value(0)
spi.write(bytearray([c]))
def data(d):
dc.value(1)
spi.write(bytearray([d]))
rst.value(1)
time.sleep_ms(100)
rst.value(0)
time.sleep_ms(100)
rst.value(1)
time.sleep_ms(200)
cmd(0x11)
time.sleep_ms(200)
cmd(0x29)
Does anyone know if:
this display needs a special init sequence,
different SPI mode,
or if the module itself might be defective?