Why does it work with SoftSPI on Display without CS but not on SPI?

[TecDroiD]

Hi,

I'm playing around with those tiny displays from aliexpress which don't have CS (btw. I also tried to patch those things for adding CS) like this one https://de.aliexpress.com/item/32880670572.html and am a litttttttttle confused now..

while SPI does not work, SoftSPI does. Even if I set both to same frequency of 500khz (which sadly is max for SoftSPI).
I tried this on ESP32-S3 as well as RP-Pico board. Both with the same result.

So while this works:

...
spi1 = SoftSPI(baudrate=500000, polarity=1, phase=0, sck=spi1_sck, mosi=spi1_mosi, miso=spi1_miso)
print(spi1)
display = st7789py.ST7789(spi1, disp_width, disp_width,
                          reset=st7789_res,
                          dc=st7789_dc, cs=spi1_cs, 
                          )

print("start")
start = time.ticks_ms()
display.fill(st7789py.RED)
end = time.ticks_diff(time.ticks_ms(), start)
print(f"took {end}ms.") # takes 2261ms on rp2, 3361ms on esp32

this doesn't

...
spi1 = SPI(1, baudrate=500000, polarity=1, phase=0, sck=spi1_sck, mosi=spi1_mosi, miso=spi1_miso)
... # rest is same

[TecDroiD]

I bought a display with cs and hardware SPI doesn't work either.. So what's going on there?

---

Edit: It does work.. using polarity 0. so, it's an issue with the cs pin..