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Hi.
My customer use PSoC 4100S Plus.
I understand that the raw count is adjusted by 85% (+/- 10%) when the IDAC is autocalibrated.
When the resolution is 12 bits, it is recognized as within the range of 3067 (4090 x 0.75) to 3885 (4090 x 0.95).
However, it may fall below or exceed 3067-3885.
I have not touched the sensor.
What could be the cause?
Best Regards.
Solved! Go to Solution.
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Hi taas_3144281,
Yes, incorrect calibration maybe due to less Cp (< 5pF). If Cp < 5 pF, advise the customer to add a parallel capacitor of 4.7 pF to the sensor pin to intentionally add the sensor capacitance. See figure below:
Regards,
Bragadeesh
Bragadeesh
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Hi taas_3144281,
Can you please check the return of CapSense_Start() and check if the calibration passed or failed?
1. Calibration can fail if the Cp is too high/ too low (Acceptable range is 5 to 200 pF).
2. It could also fail if Fsw is set incorrectly.
Are you using V7.0 CapSense component for testing?
For more info, refer section 5.3.5.7 I am unable to calibrate my system to 85 percent in CapSense design guide
https://www.cypress.com/file/46081/download
Regards,
Bragadeesh
Bragadeesh
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Dear Bragadeesh-san
Thank you for your answer.
There seems to be no problem with these two conditions.
If there is no problem, is it stable at 85%?
Best Regards,
Asanuma
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Hi taas_3144281,
As per validation, we guarantee the following:
Please let us know the Cp of your sensor and tuning parameters set in your case.
Also, let us know the calibrated rawcounts.
Regards,
Bragadeesh
Bragadeesh
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Dear Bragadeesh-san
Thank you for your answer.
I'm sorry. When I asked the customer to check the Cp again, the Cp of the button was 3.
When Fsw was changed from 6000 to 3000, Raw Count was calibrated to 3030.
May I think it's because of Cp?
What is the cause of the change in raw count of ±10% when Cp is within the range?
Best Regards,
Asanuma
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Hi taas_3144281,
Yes, incorrect calibration maybe due to less Cp (< 5pF). If Cp < 5 pF, advise the customer to add a parallel capacitor of 4.7 pF to the sensor pin to intentionally add the sensor capacitance. See figure below:
Regards,
Bragadeesh
Bragadeesh
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Dear Bragadeesh-san
Thank you for your answer.
Best Regards,
Asanuma