Explorer pHAT with Scroll pHAT HD - Errors


#1

I try to use the Explorer pHAT with a Scroll pHAT HD on a Raspberry Pi Zero W. When I try to start the test script for the Scroll pHAT HD I get the following error:

Traceback (most recent call last):
File “eyes.py”, line 3, in
import scrollphathd
File “/usr/lib/python3/dist-packages/scrollphathd/init.py”, line 25, in
display = is31fl3731.ScrollPhatHD(i2c, gamma_table=is31fl3731.LED_GAMMA)
File “/usr/lib/python3/dist-packages/scrollphathd/is31fl3731.py”, line 71, in init
raise e
File “/usr/lib/python3/dist-packages/scrollphathd/is31fl3731.py”, line 67, in init
self._reset()
File “/usr/lib/python3/dist-packages/scrollphathd/is31fl3731.py”, line 459, in _reset
self._sleep(True)
File “/usr/lib/python3/dist-packages/scrollphathd/is31fl3731.py”, line 464, in _sleep
return self._register(_CONFIG_BANK, _SHUTDOWN_REGISTER, not value)
File “/usr/lib/python3/dist-packages/scrollphathd/is31fl3731.py”, line 489, in _register
self._bank(bank)
File “/usr/lib/python3/dist-packages/scrollphathd/is31fl3731.py”, line 484, in _bank
self.i2c.write_i2c_block_data(self.address, _BANK_ADDRESS, [bank])
OSError: [Errno 121] Remote I/O error

But this worked without the Explorer pHAT.
And when I try to start the Explorer pHAT test script I sometimes get:

Warning, could not find Analog or Touch…
Please check your i2c settings!

But when I restart the Script for the Explorer pHAT it works normally… and sometimes later I get the error above again…

with i2cdetect -y 1 I see both pHATs:

 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: – -- – -- 74 – -- –

I am currently clueless…


#2

How are you wiring the two pHATs to your Pi?


#3

The Explorer pHAT is mounted on the Pi GPIO with the GPIO Header an the Scoll pHAT HD I wired with the Pinout Layout from https://pinout.xyz/pinout/scroll_phat_hd with 3 wires to the Pi GPIO 5V, BCM2 (sda) and BCM3 (scl) from the pHAT


#4

While it doesn’t make it so clear- the Scroll pHAT HD also needs the ground connections wired or there’s effectively no power supply. Often a HAT/pHAT can need more than one ground connection because some parts of the circuit may be isolated from others, but if you wire the ground pins together they need only connect to one ground on the Pi side.


#5

Okay. I already tried the wiring also with ground but with only one ground wire to one pin. I will retry it again with all grounds wired to the pi. Thank you for this input!