Raspberry Pi 4 st7789 breakout not working

[owlhor]

I'm trying to use Raspberrypi4 with st7789. scrolling_text.py works. But There're nothing happen in the display. I'm following this for the circuit [ https://i.stack.imgur.com/ouTmF.jpg ].

[Gadgetoid]

This library was written originally for our Pirate Audio boards and Breakout Garden breakouts, and the examples tend to assume you're using one of those.

For other boards you will need to adjust the examples to use whatever pins you're wiring your breakout to. This is where you would change that in scrolling-text.py for example:

https://github.com/pimoroni/st7789-python/blob/fa6195dcb7d12e3969f047ce2b71b2a5b3ee417c/examples/scrolling-text.py#L12-L18

[Gadgetoid]

The alternative, if you're following the pinout in the linked image, is to change these pins:

For the ones documented on one of the Pirate Audio breakouts: https://pinout.xyz/pinout/pirate_audio_headphone_amp

SCL	SDA	RES	DC	BLK
11	10	22	9	13

And I'm guessing chip-select on this breakout is tied on to save a pin so you can ignore it.

[owlhor]

I've tried. It still doesn't work.

[Gadgetoid]

Well, for starters your backlight is connected to GPIO 13, not GPIO 19 so the code should be updated accordingly (though to be fair, it does look like the backlight is on in your picture).

Secondly, perhaps the "res" (Reset, I guess) pin needs to be pulled in some direction for this module to work. I can't seem to find any documentation for it. Might be worth setting GPIO 22 as an output driven HIGH.

Finally, 80MHz might be a little optimistic for a breakout at the end of jump wire. Change 80 * 1000 * 1000 to 1 * 1000 * 1000 just to see if anything happens, and if it works you can raise the SPI speed until it breaks and drop back a little.

[owlhor]

Still doesn't work. I tried GPIO.output(22, GPIO.HIGH) , connect BLK to GPIO 19 (pin 35) and change SPI speed.

[Gadgetoid]

I don't there's anything else I can suggest- you should contact the seller of the breakout for further support.