USB audio i2c best practice

[lmariotti]

Hi Everyone,

I'm working on a project that use sw_usb_audio 9.0.0.
I need to share the same i2c line with multiple tasks.
So far I've followed the preset route and I've something like:

Code: Select all

void Board_i2c_task(chanend c, client interface i2c_master_if i2c)
{
  while(1)
  {
    select
    {
      case c :> unsigned cmd:
        if(cmd == CMD_DAC_INIT)
        {
          unsafe
          {
		// Access i2c bus
          }
        }
        else if(cmd == CMD_READ_IO_EXPANDER)
        {
          unsafe
          {
		// Access i2c bus
          }
        }
        else if(cmd == CMD_WRITE_IO_EXPANDER)
        {
          unsafe
          {
		// Access i2c bus
          }
        }
        else if(...)
        	// And so on with multiple commands

The chanend is shared between:

• A timed task (10Hz)

• A GPIO event task

• AudioHwConfig

Is that implementation correct or may cause trubles?
If not what's a best practice to access the same i2c bus from multiple tasks?

Thanks everyone

[andrewxcav]

If you aren't running out of chanends I would suggest making a dedicated task that can write to the I2C task and read a chanend from your other 3 tasks. This multiplexer task should probably have the form:

task(i2c_chan, task chans ... )
{
initialization code if any

while(1)
{
select{ // on each chanend and/or a 10Hz. timer if you wanted to pull that task into this one to save on cores or chanends...
...
}
}
}