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pimoroni / automation-hat

Python library and examples for the Pimoroni Automation HAT, pHAT and HAT Mini
https://shop.pimoroni.com/products/automation-hat
MIT License
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Receiving 'Automation pHAT detected...' message with no hat connected #11

Closed stefancrain closed 6 years ago

stefancrain commented 7 years ago

With a fresh install of raspbianI tried to use this example file. I had no hat attached and had never attached a hat. I still see that it detected one and promptly failed. 

pi@raspberrypi:~ $ python3 ./example.py
Automation pHAT detected... 
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python3.4/threading.py", line 920, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3/dist-packages/automationhat/pins.py", line 37, in run
    if self.todo() is False:
  File "/usr/lib/python3/dist-packages/automationhat/__init__.py", line 293, in _update_adc
    analog._update()
  File "/usr/lib/python3/dist-packages/automationhat/pins.py", line 92, in handler
    return self._do(name, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/automationhat/pins.py", line 111, in _do
    _results[node] = handler(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/automationhat/__init__.py", line 122, in _update
    self.value = ads1015.read(self.channel)
  File "/usr/lib/python3/dist-packages/automationhat/ads1015.py", line 42, in read
    self.i2c_bus.write_i2c_block_data(self.addr, REG_CFG, [(config >> 8) & 0xFF, config & 0xFF])
OSError: [Errno 121] Remote I/O error

^CTraceback (most recent call last):
  File "./example.py", line 16, in <module>
    time.sleep(0.1)
KeyboardInterrupt

Seems like thats an error with detecting that the hat is connected.

Gadgetoid commented 7 years ago

There's no real detection happening, the library is just attempting to differentiate between pHAT and HAT by checking for the presence/absence of certain i2c devices (the sn3218 in this case). It's a pretty naive check and is definitely not bulletproof. Yes, the library will fail if you don't have a HAT or pHAT connected.

RogueM commented 7 years ago

to add to this though - I am aware that there is a gap on the logic when no HAT/pHAT is attached, it shouldn't claim a pHAT is attached.

I'll look at it and try to improve when I have a minute but apart from obviously not claiming a pHAT is attached when none are that is not going to magically make things work when there is no hardware attached ;-)

stefancrain commented 7 years ago

@RogueM Thats exactly what I was looking for. I was trying to debug a hardware failure last month and it was very confusing to see that my Hat had changed into a pHat.

Gadgetoid commented 6 years ago

I appreciate this is a somewhat late update, but as part of the defer-setup update I have in the pipeline for Automation HAT/pHAT these messages would be removed and replaced with a RuntimeError when the ADC is not detected. See: https://github.com/pimoroni/automation-hat/tree/defer-setup/library/automationhat

These messages constitute import-time side-effects, and aren't really very Pythonic. While they could be helpful to some users, I've surmised they do more harm than good and will take steps to avoid patterns like this in future.