Chipkit uC32 change I2C speed

[ryanpandey]

Hello. I'm trying to change the speed of the I2C bus from the default (I think 100kHz) to 1.7MHz. In which file do I change the speed?

I found the following in DTWI.cpp (lines 136 - 141):

    // put a default of 100KHz
    // use F_CPU because __PIC32_pbClk is not set up yet
    // as constructor run before MPIDE Init; however, this would be the correct
    // value at this point as noone has the chance to change the clock freq
    // later we can use __PIC32_pbClk; which is used in masterStart
    ptwi->ixBrg.reg = (F_CPU/FQ100KHz/2) - (((F_CPU / 10000000) * 26) / 25) - 2;

 

Changing the 10000000 to a 40000000 (for 400kHz speed) did not seem to change the I2C bus speed. Is there another place the change needs to be made? Thanks.

[jpeyron]

Hi @ryanpandey,

Here is a forum thread that discusses this post.

cheers,

Jon