8000 Trinket M0: SPI not working correctly · Issue #219 · adafruit/circuitpython · GitHub
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Trinket M0: SPI not working correctly #219
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@deshipu

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@deshipu

I'm trying to get a ST7735 display to work with Trinket M0, and it seems that Trinket's SPI behaves very strangely. Here is a screenshot of a capture of a fragment of the transmission:

cap1

and here is a close-up on one of the fragments:

cap2

Here's the complete capture for analysis:
cap.logicdata.zip

And here is the code that I used to capture that:

>>> import busio, digitalio, board
>>> from adafruit_rgb_display import st7735
>>> cs = digitalio.DigitalInOut(board.APA102_MOSI)
>>> dc = digitalio.DigitalInOut(board.D0)
>>> rst = digitalio.DigitalInOut(board.D1)
>>> spi = busio.SPI(clock=board.D3, MOSI=board.D4)
>>> d = st7735.ST7735R(spi, cs=cs, dc=dc, rst=rst)

Looking at the capture, two things are immediately striking:

  1. the polarity of the data line is wrong
  2. there are strange blips happening on both clock and data lines in between the actual bytes being transmitted

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