assistance using the TSI module on a PT32

[hightech]

I'm looking for  a little assistance using the TSI module on a PT32. I have an application that has touch inputs working well.  Now I need to optimize the application for power by putting the cpu into stop mode, and periodically waking to scan ALL of the touch sensors.  The TSS library has a mode to wake on a single key, that will not work for my application. 

[Andoni_Gonzalez]

Hello James, Gordy,

Vicente's suggestion to review the example code will definitely help you out. I just wanted to add something to clear things out.

The best way to configure low power applications for touch sensing is using the TSI capabilities of working in low power mode. You can set the RTC to trigger a scan every x time and the TSI will scan only one electrode. All of this while working in low power. Whenever there is a touch on this particular electrode the TSI will wake up the MCU and process will continue. This way the MCU does not wake up often to check if there was a touch or not.

I hope this clear things a bit.

Regards!

Andoni

[vicentegomez]

Hi James

Sorry for the late response, you can check the TWR-S08PT60 Labs, the lab 1 is a TSI sample code that goes to low power after 5 sec.

I hope this will help you.
Have a great day,
Vicente

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[GordyCarlson]

Thanks Pedro!

    Jim and I will review the sample code within the lab, and build/run it.   Will advise if we have any more questions.  Thanks for the pointer into this sample,  we were previously unable to locate an example.

Gordy Carlson

Freescale FAE

Upstate NY

[GordyCarlson]

I've met with Jim and discussed methods for entering STOP mode on the S08PT32.  We clarified that the Real Time Counter (RTC) is used to wake up the S08PT32 from STOP Mode, rather than any other timers.  Jim has successfully modified his code to achieve this.  RTC is successfully bringing PT32 out of STOP.

Here is his additional email response.  I will next look at the TSS Library and try to determine if there is a reason the TSS stops working after 100ms.  I've added this additional comments to this thread, in the event another community user has also found a limitation or a workaround.

------From Jim McLean--------

The plan is to be in stop mode, and every half to 1 second wake and check for touch inputs.

What is consistent with the TSS is that it works okay when it is in a loop and called regularly.  When I use a periodic timer to schedule a scan, rather than continually looping, the TSS quits working when the scan interval is greater than 100msec.  Shorter interrupt times (<30msec) work okay, but as I increase the interval, the TSS starts missing touches.  I've tried using the TSS save and restore functions prior to sleep and wake, no difference.

Yesterday I was going to try using the low power modes built into the TSS library through PE, but the options were not available.  Perhaps the PT family came up short on the TSS implementation.