<![CDATA[Atom to Atom via I2C]]>Hi Folks,

I'm trying to get 2 M5Stack Atom's to talk together via I2C, or more specifcially, SoftI2C in Micropython.

I've flashed both devices with Micropython 1.18 and have code on device A that looks like:

import machine

i2c = machine.SoftI2C(scl=machine.Pin(26), sda=machine.Pin(32), freq=400000, timeout=50000)

data = i2c.readfrom_mem(2, 1, 10)
print(data.decode('utf-8'), end="")

Then on device B, I have the code to send data:

import machine

i2c = machine.SoftI2C(scl=machine.Pin(26), sda=machine.Pin(32), freq=400000, timeout=50000)

i2c.writeto_mem(2, 1, bytearray("Hello World"))

Nothing seems to come through, I have tried i2c.scan() however it just returns and empty list on both.

I realise these are not hardware I2C pins, but they are for the Grove cable I'm using to power the second Atom.

If anyone has any examples/reference/docs or general tips, that would be great.

]]>https://community.m5stack.com/topic/4221/atom-to-atom-via-i2cRSS for NodeWed, 29 Apr 2026 06:49:45 GMTWed, 20 Apr 2022 10:55:58 GMT60<![CDATA[Reply to Atom to Atom via I2C on Fri, 13 May 2022 10:03:38 GMT]]>@exie @felmue I have never worked with micropython, however ESP32 can act as a slave on the I2C bus without any issues, irrespective of the pins that are used (any pair of GPIO can, in fact, be used as front-end for the I2C interface). I've taken a peek to the linked thread and the idea of continuously polling the bus to reply to an address as a slave is quite cumbersome and to say the least, inefficient.

]]>https://community.m5stack.com/post/17479https://community.m5stack.com/post/17479Fri, 13 May 2022 10:03:38 GMT<![CDATA[Reply to Atom to Atom via I2C on Wed, 20 Apr 2022 22:33:52 GMT]]>@felmue Yes, I think you are absolutely right.

I just struggled to find any useful references to do this.
Today I came across this post:
https://forum.micropython.org/viewtopic.php?t=5320

So I will try this later today and see how I go.

]]>https://community.m5stack.com/post/17231https://community.m5stack.com/post/17231Wed, 20 Apr 2022 22:33:52 GMT<![CDATA[Reply to Atom to Atom via I2C on Wed, 20 Apr 2022 15:14:44 GMT]]>Hello @Exie

you would need one M5Atom to assume the I2C slave role. Right now both of your M5Atoms are acting as I2C master, but on a given I2C bus there can only be one master.

That said, I have no idea whether ESP32 can assume the I2C slave role or not and if yes, whether that functionality is accessible from within micropython.

Thanks
Felix

]]>https://community.m5stack.com/post/17226https://community.m5stack.com/post/17226Wed, 20 Apr 2022 15:14:44 GMT