Support for PCF8575 (not 8574)

[Cover1987]

Hi guys,

i got a board with an PCF8575. Unfortunately it's not supported (yet?) by ESPEasy.
I got some I/O working by trying out some combinations (Forced i2c slow mode, used PCF8574 and MCP23017) but i didnt got (for sure) all I/Os to work.

I dont know if it's a hard act to add the PCF8575 to the next build, but i would be very happy about it.
Best Regards
Stefan

[Ath]

Hi,

All I could find for the PFC8575, compared to the PCF8574, is that it supports 16 I/O pins (not supported by the PCF8574 plugin, but the first 8 I/O pins should work), and it does not seem to have pull-up resistors included in the chip. So it will not give a 'high' output if the pin isn't (externally) pulled up to VCC (3.3V I assume).
So in fact it should at least partially work using the PCF8574 plugin.

Does it show up in the I2C scanner output (Tools tab)?

[Cover1987]

Pins have pull up resistors, that's not a problem.

I2C scan shows me:
(Device) Switch input - MCP23017
(Device) Switch input - PCF8574

[Ath]

Ah, so then the only 'issue' here is that the first 8 I/O pins are (probably) working, but the second set of 8 I/O pins not. That's to be expected, as the PCF8574 plugin only 'knows' about 8 I/O pins. And I don't expect the MCP23017 (that does support 16 I/O pins) to be software-compatible with the PCF8574/5, but I have never tried that.

That would be a feature request to have that plugin to also support PCF8575, can you create an issue for that on Github, please, so it will stay in sight? You could include the term P019, as that's the plugin ID for the PCF8574.

[Cover1987]

Opend the issue

https://github.com/letscontrolit/ESPEasy/issues/3871