SMBUS implementation in imx8m plus

[aaronrenny]

Hi all,

We are working on imx8mplus based custom board. Just wanted to know if we can configure the imx8mplus to act as a SMBUS master in order to communicate with an SMBUS slave connected to the I2C bus. If yes, are there any sample application code using which we can get a start.

Hoping for a response,

Aaron

[OrenP]

to be more precise, I understand SMBus, just not how to enable the SMBus controller in this board with the available libraries. Is there an existing configuration that needs to be set? or manually send a message to the controller in order to configure it for SMBus?

[Sanket_Parekh · Accepted solution]

Hello @aaronrenny ,

->SMB is based on the principles of operation of I2C.
->One has to enable the smbus controller in 8mp soc and configure the register , basically it is part of the i2c bus
->SMBus provides a control bus for the system to pass messages to and from devices instead of using individual control lines, helping to reduce pin count and system wires.
->The SMBus specification refers to three types of devices: host, master, and slave.

->A device can be master only or slave only. It may act as a slave most of the time, but in special instances it becomes a master.
• A master is a device that issues commands, generates the clocks, and terminates the transfer.
• A slave is a device that receives or responds to a command.

->Now one can use smb protocol to communicate with slave.

There are Reserved SMBus addresses.
where 0th bit one can decide to read or write to/from the slave.

To give command and exact data to particular slave please refer Table-3 from the below link.
https://www.nxp.com/docs/en/application-note/AN4471.pdf

for more details on SMB one can refer below links.
https://www.nxp.com/docs/en/data-sheet/PCA6416A.pdf
https://www.nxp.com/docs/en/application-note/AN4471.pdf

Refer <linux_source_code>/drivers/input/mouse/elan_i2c_smbus.c for more details on coding part.

Thanks & Regards,

Sanket Parekh

[aaronrenny]

Hi @Sanket_Parekh ,

Thank you for the detailed input, I will try out the suggestions given.

Thanks,

Aaron

[OrenP]

Did you manage to make it work? I'm having the same problem and need to know which register to set in order to change the configuration to SMBus instead of I2C.

Thank you in advance.