TSS Key detection failure

[sureshjaggal]

Dear Folks,

I am using KL05Z Microcontroller and TSSv3.1 for recognising touch Inputs, I have configured the touch detection through the TSI method.

Normallay my application works fine but once in a while a particular key is not detected , I checked the signal on the oscilloscope when the key recognation stops , there is no Signal generated for that particular key but all the other keys function normally.

On restart of the µC again everything is normal.

I just checked with the stuck key configuration , but i see that stuck key is used to recognise the state high condition (a constant high Input at the key) .

Questions

1) Why does the Signal Generation stop only for one key from the µc

2) Are there ways to recognise such a condition in TSS and re initialize the TSS module.

Best regards,

Suresh Jaggal.

[vicentegomez]

Hi Suresh

This is normally due the base line is increasing on that electrode, and when you touch it the capacitance change is not enough to create a delta with the base line.

1) Why does the Signal Generation stop only for one key from the µc,

Normally this is due a noise on the electrode.

2)Are there ways to recognise such a condition in TSS and re initialize the TSS module.

By TSS you mean the TSS library, if this is the case yes you can use the autocalibration to avoid this condition, if you are not using the TSS library you can disable the TSI module and re enable in order to perform a recalibration, but I do not know if this is posible for your aplication.

Also you can test with different values on NSCN or change the values on  EXTCHRG on TSIx_GENCS

I hope this will help you.

Regards

Vicente Gomez

[sureshjaggal]

Dear Mr. Salazar,

Thank you for getting back to me with the answer.

I am sorry to missout the configaration Information about my Project. I am using TSS3.1 library with TSI sense method.

I am already using the autocalibration  option for sensing the touch Input .

I am not completely in accord with your answer that it is due to noise. If it were due to  noise the key should not be detected or detected at random intervals or false detection . But the complete Signal Generation stops on that particular electrode. I have checked for the Signal from the µc pin no Signal is present at that particular pin.

Are there any further suggestions with respect  to this question.

Best regards,

Suresh Jaggal.

[vicentegomez]

Hi Suresh

If the pin that has problem share with the ADC? are you using the ADC module? If yes, can you please test it with the ADC disable

Would be possible that you add Freemaster on your project in order to see the signal?

Regards

Vicente Gomez

[sureshjaggal]

Hi Vicente,

No I am not using ADC module , sorry there is no enough Memory to add the Freemaster to my Project.

This error occurs very rarely, I have measured the out pin of µc when this error persisted.

Best regards,

Suresh Jaggal.

[vicentegomez]

I recommend that you perform a manual calibration or hardware re calibration ( I do not remember which one reset the base line)

regards

Vicente Gomez