io_expander probable bugs

[mark-hoy]

I'm trying to create an io_expander for pca9557.py and was looking at the included io_expander samples and I think there are some copy/paste typos.

In api_drivers/common_api_drivers/io_expander/ch422g.py

    def _set_level(self, level):
        if self._mode == self.OUT:
            if level:
                # 3. High level && Set 0 to output high
                # 4. Low level && Set 0 to output low
                states = Pin._output_states & ~self.__bit
            else:
                # 1. High level && Set 1 to output high
                # 2. Low level && Set 1 to output low
                states = Pin._output_states | self.__bit

            # Write to reg only when different */
            if states != Pin._output_states:
                self._write_reg(_REG_OUTPUT, states)
                Pin._output_states = states

but api_drivers/common_api_drivers/io_expander/{ht8574a.py,ht8574b.py,tca9535.py,tca9554.py} don't output the changed state on the self.__write_reg() call.

In addition the states assignments seem reversed between the ch422g.py and the others ( states & ~self.__bit ) vs ( states | self.__bit) (which may be intentional, I have not looked up the specifics the parts themselves) but it seems incorrect offhand.

    def _set_level(self, level):
        if self._mode == self.OUT:
            if level:
                states = Pin._output_states | self.__bit
            else:
                states = Pin._output_states & ~self.__bit

            # 0nly set if there is an actual change
            if states != Pin._output_states:
                self.__write_reg(Pin._output_states)
                Pin._output_states = states

Changed Code

            if level:
<<                states = Pin._output_states | self.__bit
>>                states = Pin._output_states & ~self.__bit

            else:
<<                states = Pin._output_states & ~self.__bit
>>                states = Pin._output_states | self.__bit

            # 0nly set if there is an actual change
            if states != Pin._output_states:
<<                 self.__write_reg(Pin._output_states)
>>                 self.__write_reg(states)
                Pin._output_states = states

[kdschlosser]

I believe that a 0 bit state turns the pin on and a 1 bit state turns the pin off.
I would also have to check the specification for the IC to make sure.

[mark-hoy]

Yeah, it just seems unlikely be flipped for all but the ch422g.py (but not impossible).

I'm pretty sure the output change is correct.

[kdschlosser]

if you find it's flipped then go ahead a fix it and submit a PR for it. You found found it, fixed it you should get the credit for doing that work.