Papirus Zero Doesnt work with GPIO cable, but works without??

[aixsyd]

If I attach my Papirus Zero directly to my Pi Zero with header attached, it works fine.

i2cdetect -y 1

`pi@raspberrypi:~ $ i2cdetect -y 1

 0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f

00: -- -- -- -- -- -- -- -- -- -- -- -- --

10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

40: -- -- -- -- -- -- -- -- 48 -- -- -- -- -- -- --

50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

70: -- -- -- -- -- -- -- --
`

but if I put a GPIO ribbon cable between the two, i2cdetect fails to detect #48 and no papirus commands work. I have tried reseating, and switching cable directions.

[tvoverbeek]

Probably the signal quality deteriorates due to the longer cable.
You can try to lower the i2c baudrate (default = 100000).
This can be set by changing a line in /boot/config.txt:
Change dtparam=i2c_arm=on to
dtparam=i2c_arm=on,i2c_arm_baudrate=50000 for example.