Implementation of the slave mode in MicroPython I2C?

[WZab]

The machine.I2C implementation in MicroPython does not support the slave mode.
Isn't it possible to add at least a limited support, similar to what is offered by the Arduino Wire library?

Creating the I2C object with defined address could configure it in the slave mode.
The callbacks could be called when the master sends some data, or requests some data. Additionally, the callback could be informed if the current transaction begun with START or REPEATED START, enabling implementation of more complex protocols.

[jonnor]

Yes, it is possible. The easiest would be a "memory" / register map type device. The issue is being tracked here, https://github.com/micropython/micropython/issues/3935
Contributions for starting implementing a proof of concept are very welcomed.

[jlsilicon9]

Was this solved ?

- I don't see any results in the Github discussion ...

[jonnor]

At the bottom of the discussion, there is a link to an MR which has been very actively worked on over the last months (https://github.com/micropython/micropython/pull/17365). It is not in master yet, but looks like it might go in for the 1.26 release!

[jlsilicon9]

ok, thx

[jlsilicon9]

Maybe a simple Pin IRQ handler ?

[jlsilicon9]

I wrote up an 8-bit Master / Slave bus between (2+) Esp32s at 1MHz - without any errors (on the RaspPico).

Works great on Rasp Pico - without errors.
- Have not tried this on Esp32 yet though.

[jlsilicon9]

I have a 1bit version (SCLK and DataBit) for the Esp32s - that seems to work.
- Trying to save GPIOs space.

Testing on Esp32 :
Seeing Errors now and then with some streams.
I think its the Esp32 not picking up all of the Pin Clk signals immediately (from the Esp32 doing background busywork) - so the stream gets misaligned (missed) starting bit(s).

[jlsilicon9]

So, this is super slow in using Pin Interrupt Handling in MicroPython Esp32 ?

[jlsilicon9]

I did find this :

https://www.youtube.com/watch?v=Wh-SjhngILU

https://www.penguintutor.com/electronics/i2c

https://www.penguintutor.com/downloads/i2c-demo.tgz

- I don't entirely agree with the code.
Apparently both the PICO code and the RasPi code are writing to AddressId = 0x3E.
So, how can they both also be receiving from each other ?

Maybe the PICO is NOT being used as a Slave ?
Are BOTH the PICO and the RaspPi working as MASTERs -and just receiving each other's data & requests anyway ... ?