ST7789 Display Module not working

lbthomsen
Posts: 3
Joined: Mon Oct 21, 2019 1:22 am

ST7789 Display Module not working

Postby lbthomsen » Mon Oct 21, 2019 1:37 am

I have a bunch of ST7789 1" display modules, which I have been trying to make work with the lvgl_example.

Image
Image

First of all let me stress that I _KNOW_ the modules are working (they run fine with https://github.com/Bodmer/TFT_eSPI).

Also, I have a few ILI9341 modules and they work fine with the lvgl_example - so it is also not a build or flash issue.

In short - if I hook up the ILI9341 everything works - if I hook up the ST7789 display I simply get a blank screen.

A few things I have noticed. Unlike the ILI9341, the ST7789 module does not have a MISO signal, but I have tried not to connect the MISO on the ILI9341 and that still works fine. Second issue - the ST7789 does not have a CS signal. Reading up on esp-idf SPI it should be possible to set the CS to -1 and I have tried to modify the Kconfig.projbuild to allow -1 - that made no difference at all.

These modules are quite cheap and readily available so my question is - has anyone managed to make them work?

//Lars...

chegewara
Posts: 873
Joined: Wed Jun 14, 2017 9:00 pm

Re: ST7789 Display Module not working

Postby chegewara » Mon Oct 21, 2019 6:49 am

I have to disappoint you, you won't find MISO and CS pins in I2C device and display from pictures is IIC standard.

lbthomsen
Posts: 3
Joined: Mon Oct 21, 2019 1:22 am

Re: ST7789 Display Module not working

Postby lbthomsen » Mon Oct 21, 2019 8:17 am

chegewara wrote:
Mon Oct 21, 2019 6:49 am
I have to disappoint you, you won't find MISO and CS pins in I2C device and display from pictures is IIC standard.
No, these are SPI even though they - if you read the labels - look like i2c. SDA is MOSI (see working initalization here: https://github.com/Bodmer/TFT_eSPI/blob ... 789_Init.h).

lbthomsen
Posts: 3
Joined: Mon Oct 21, 2019 1:22 am

Re: ST7789 Display Module not working

Postby lbthomsen » Mon Oct 21, 2019 8:23 am

chegewara wrote:
Mon Oct 21, 2019 6:49 am
I have to disappoint you, you won't find MISO and CS pins in I2C device and display from pictures is IIC standard.
Also documented in the datasheet of the display driver that it is in fact a SPI port https://www.rhydolabz.com/documents/33/ST7789.pdf.

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