Hi & thanks for the great work!

I was in need of using the interrupt functionality of the chip and be more compatible with machine.Pin.
If anybody is interested I could publish the code - let me know.

New functionality:

• Pin class like machine.Pin
• Using INT[AB] pins (mirrored) like machine.Pin.irq() with callback

Changed constructor:

• An I2C object is given instead of sda/scl-pins like in the module for ads1x15 to have just one central I2C object
• New argument for config of mcp230xx features like providing a machine.Pin object where the INT[AB] of the mcp230xx is wired to on the esp8266

When I use the example code on the library:

import mcp, machine

#To test that the mcp is there
i2c = machine.I2C(scl=machine.Pin(13), sda=machine.Pin(12))
address = hex(i2c.scan()[0])
print(address)

io = mcp.MCP23017(gpioScl=13, gpioSda=12)

outPins = list(range(10,16))
nextVals = {}
for pinNum in outPins:
    io.setup(pinNum, mcp.OUT)
    nextVals[pinNum] = True
io.output_pins(nextVals)

# monitors and prints some input pins
inPins = list(range(0,10))
for pinNum in inPins:
    io.setup(pinNum, mcp.IN)
while True:
    print(io.input_pins(inPins))`

I get the following error:

Traceback (most recent call last):
  File "main.py", line 8, in <module>
  File "/lib/mcp.py", line 56, in __init__
  File "/lib/mcp.py", line 156, in write_iodir
  File "/lib/mcp.py", line 67, in writeList
OSError: [Errno 110] ETIMEDOUT

MicroPython v1.9.4-8-ga9a3caad0 on 2018-05-11; ESP module with ESP8266

I have spent hours replicating what the library does but I can't spot the error.

Any idea why?

Thanks for this great mcp230xx library. This makes the handling of my MCP23017 much smoother. However I had to make some adjustments to make it work on my pyboard v1.1. On the pyboard the I2C class of the pyb package must be used (different to the I2C class of the machine package which is used on other controllers). For details on the differences see https://learn.adafruit.com/micropython-hardware-i2c-devices/i2c-master. They are both incompatible so I made the approach of passing an i2c object as parameter to the MCP class. The modifications I made provide a module that can be used either on the pyboard or on other boards. The drawback is that the functions signature changes. I made a PR with my changes if you would like to include them to make this module more universal.

Kind Regards

Upon reading a pin it becomes impossible to write to another one

Minimal implementation:

import mcp

mcp1 = mcp.MCP23017(address=0x20, gpioScl=22, gpioSda=21)
mcp1.setup(0, mcp.OUT)
mcp1.setup(5, mcp.IN)
mcp1.pullup(5, True)

mcp1.output(0, 0)
print(mcp1.input(5))
mcp1.output(0, 0)

Returns

False
Traceback (most recent call last):
  File "boot.py", line 9, in <module>
  File "mcp.py", line 92, in output
  File "mcp.py", line 105, in output_pins
TypeError: 'bytes' object does not support item assignment

Fix appears to be simple, just changing line 71 to return a bytearray to keep self.gpio in the original type set on the __init__()

def readList(self, register, length):
        """Introduced to match the readList implementation of the Adafruit I2C _device member"""
        return bytearray(self.i2c.readfrom_mem(self.address, register, length))