Today I received my WT32-SC01 esp32 based board and I had some problems configuring the TFT driver ( ST7796S ).
Initially I compiled LVGL with LV_COLOR_DEPTH=16 and then I added LV_COLOR_16_SWAP=1, but nothing changes.
When I write directly to the LCD (no LVGL involved), I still see different colors than I spected. I already tried to change the RBG/BGR color format on the MADCTL register, the inversion, the SPI endian… but I never got the correct colors.
The RGB565 colors I think LVGL needs are these, at least this is what I see on internet:
RED = 0xF800
GREEN = 0x07E0
BLUE = 0x001F
But with my LCD configuration I got:
Black and white are ok, so there is no LCD inversion needed, RED is ok, but GREEN and BLUE are swapped…and I dont know why…
Here is the code Im using test_st7796s.py.txt (3.8 KB)
The driver datasheed:
I tried to swap the LVGL buffer at disp_drv_flush_cb via software before send it to the LCD with this function and now my LCD works fine, slow, but with correct colors.
def software_swap( buf ):
for i in range(0, len(buf), 2):
buf0 = buf[i+0]
buf1 = buf[i+1]
buf[i+0] = buf1
buf[i+1] = buf0
So looks that the problem is the LV_COLOR_SWAP_16=1?
My build command is:
make -C ports/esp32 LV_CFLAGS="-DLV_COLOR_DEPTH=16 -DLV_COLOR_16_SWAP=1" BOARD=GENERIC_SPIRAM
In previous LVGL versions I modified lv_conh.h cause there was a “#deine LV_COLOR_16_SWAP”, but in current version it isnt and Im always confused if it is the correct define.
Also I noticed that is not exposed to micropython, so probably is not the correct build command:
>>> lv.COLOR_DEPTH
16
>>> lv.COLOR_16_SWAP
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'COLOR_16_SWAP'
In LVGL on latest lv_micropython, LV_COLOR_16_SWAP was removed.
Instead, this can be configured now on runtime. When registering the display driver you also pass color_format.
The exiting drivers were also fixed to receive color_format.
Try to pass lv.COLOR_FORMAT.NATIVE_REVERSE instead of the default value.
