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Using K20 TSI Peripheral

Question asked by Alessandro Vagniluca on Oct 2, 2012
Latest reply on Oct 3, 2012 by Alessandro Vagniluca

I am trying to handle with the TSI peripheral a touch sense keypad on my custom K20DX256VLH7-based board with the Processor Expert TSS_Library component v2.6.

I use TSI only in active mode. The Bus-clock on my board is set at 48MHz and I chose this clock as TSI active mode source clock.

Also, I chose to use the AUTO trigger mode for TSI.

What is the relationship between Active Mode Clock Source (AMCLKCS), Active Mode Clock Prescaler (AMPSC), Active Mode Clock Modulo (SMOD) and trigger period in AUTO trigger mode?

I have this question, because from the K20 Reference Manual I don't understand how to get the trigger period from those register and in my system I get always a "Small Trigger Period" fault output by the TSS Library.

With my scope I see in my system that SMOD value set the trigger period in milliseconds: why?

If I set SMOD=25, trigger period is 25ms; if I set SMOD=255, trigger period is 255ms. I call TSS_Task() every 5ms, but in both case I get the "Small Trigger Period" fault.


Furthermore, the Kinetis K20-72MHz TSI has got some errata for the current chip mask 1N36B: does Processor Expert TSS_Library component v2.6 consider them (e.g. e2638 errata on the End-Of-Scan interrupt) ? Or is it up to my code ?