```PEC```-option when using the ```i2c_write()```-function?

[Florian1FRANK]

Hello,

Does smbus2 supports the PEC-option when using the i2c_write()-function as in the example below? From my experience (with version 0.4.2), it seems the PEC-option is not effective for the i2c_write()-function, do you confirm?

Example:

write = i2c_msg.write(80, [40, 50])
read = i2c_msg.read(80, 2)
with SMBus(1) as bus:
    bus.pec = 1
    bus.i2c_rdwr(write, read)

[kplindegaard]

Remember that PEC is an SMBus protocol feature while i2c_rdwr is just pure i2c communication. I.e. no PEC for that command.

[Florian1FRANK]

Thank you for the clarification. Would it be a valuable feature to have the possibility to enable the PEC for i2c_rdwr() as well?

Recently I used a chip requiring to use a I2C-message-structure + a trailing PEC byte ; for simple read actions I could use right away the smbus byte_read + in-built PEC feature of smbus2, yet for write sequences I had to use i2c_rdwr() + a self coded PEC-byte. Hence my question.

[kplindegaard]

Thanks for explaining. Interesting case and glad you pieced it together 😃

I have, however, tried to keep the lib as simple as possible and kept additional utilities to a minimum. My recommendation would thus be to to not include it and that particular device specific variations are kept outside of the lib itself. Sorry, but I hope you understand.

[Florian1FRANK]

I think my original question is clearly answered, and the 'Issue' can be closed gracefully.

Indeed keeping it simple is enough.

Maybe the documentation could gently remind the user that the inbuilt PEC feature is obviously not effective when invoking the i2c_rdwr()-function?