AnsweredAssumed Answered

KL27 I2C Speed Problem

Question asked by PHIL HALE on May 8, 2018
Latest reply on May 9, 2018 by Jing Pan

I am not quite getting the initialization of the I2C baud rate. Normally, I use the same speed of I2C for all my projects so this is never an issue. Now, I am using an SDK from somebody and they want to set their own I2C speeds for their ICs.

 

See attached I2C.c file.

 

I have "acquired" this code from the KDS 2.0 SDK library - or at least it is close. Copyright preserved.

 

My MCU is a:  MKL27Z256VFM4

System Bus Speed: 48 MHz

 

I am not able to get the speeds I need when I put this on the scope. Not even close.

 

It seems pretty clunky to get the I2Cx_F settings this way but I'm sure there is a good reason.

 

I am also getting locking up when in I2C wait states when using the setting suggested for 20 kbps.

 

I have read the double-buffering causes lock ups at these slower speeds. But, the SDI I am using from this vendor is hardcoding a rate of 20 kbps. Even when I override the inbound 20 kbps to 50 kbps the problem still occurs.

 

Any suggestions?

 

Thanks in advance.

 

Phil

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