PIC24FJ64GB004 and I2C modules

jehcc · Joined: 10 Jan 2019 Posts: 3 Location: Washington State

I am trying to convert a C library from MPLAB X, XC16 compiler, to use the CCS compiler.

My current device is PIC24FJ64GB004 which has 2 fully functional I2C modules and dedicated pins for both.
I need to have both modules enabled and running at the same time, I do not see any way to do this in the CCS manual or examples.

Thank you for any help!

dluu13 · Joined: 28 Sep 2018 Posts: 395 Location: Toronto, ON

Check the section on the #use I2C preprocessor directive. You should be able to specify I2C1 and I2C2 with unique stream names for each.

something like:
#use i2c(I2C1, ... , STREAM = MYSTREAM1)
#use i2c(I2C2, ... , STREAM = MYSTREAM2)

Ttelmah · Joined: 11 Mar 2010 Posts: 19215

One caveat.

The statement: "dedicated pins for both", is not quite true.
In fact I2C1, can be located to two different sets of I/O pins depending
on a fuse setting. Where I2C1 will actually 'go', depends on whether
ALTI2C1 or NOALTI2C1 is selected in the fuses.

dluu13 · Joined: 28 Sep 2018 Posts: 395 Location: Toronto, ON

You've also gotta specify the stream parameter in your i2c functions (i2c_start, etc). If stream parameter is not specified, then it will apply to the last encountered #use i2c

jehcc · Joined: 10 Jan 2019 Posts: 3 Location: Washington State

Thanks for the feedback! I am looking into the #use syntax to see what I can do with it.

On this device I2C1 defaults to pin 1 & 44, with alternate set by the config bits of pins 19 & 20; I2C2 pins are 23 & 24, no choice. So little flexibility here.

And I need to run both at the same time.

Again, thanks