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PSoC 4 MCU

taas_3144281
Valued Contributor

Hi.

My customer use PSoC 4100S Plus (CY8C4127AZI-S455).

My customer use CapSense.

Please tell us about the initial time of CapSense.

After power supply to PSoC, how long is the initial time of CapSense (time when touch electrode should not be touched) required?

If time is required, is initial time required when returning from sleep mode?

Best Regards.

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1 Solution
BragadeeshV
Moderator
Moderator

Hi taas_3144281​,

When the buttons are touched when supplying power (OFF to ON) the following could happen:

a. If auto - calibration is enabled, IDACs are recalculated to calibrate the new Cp to 85 % of rawcounts. (baseline remains the same as before reset)

b. If auto - calibration is disabled, the IDACs are not recalculated, therefore baseline gets updated to the new rawcounts since other hardware parameters are fixed only Cp has changed.

In both the cases, when the hand is removed you will observe reduction in rawcounts level due to Cp decrease and baseline tracks the rawcount after low baseline reset timeout. You may not observe false triggers.

Please share us a video of the issue so that we can understand your issue better.

Regards,

Bragadeesh

Regards,
Bragadeesh

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BragadeeshV
Moderator
Moderator

Hi taas_3144281​,

Can you please clarify if you want information on the Chip boot up time or the time taken to initialize CapSense?

If you are using deep sleep mode it is essential to have a wake up time of 10 uS to initialize the CapSense component. This is taken care by the API CapSense_Wakeup(). After the device has woken up from deep sleep call the API CapSense_Wakeup for proper operation of CapSense.

Regards,

Bragadeesh

Regards,
Bragadeesh
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taas_3144281
Valued Contributor

Dear Bragadeesh-san

Thank you for your answer.

I want to prevent false detection and malfunctions caused by touching the touch buttons when supplying power.

Is there any time to affect it?

Best Regards,

Asanuma

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BragadeeshV
Moderator
Moderator

Hi taas_3144281​,

When the buttons are touched when supplying power (OFF to ON) the following could happen:

a. If auto - calibration is enabled, IDACs are recalculated to calibrate the new Cp to 85 % of rawcounts. (baseline remains the same as before reset)

b. If auto - calibration is disabled, the IDACs are not recalculated, therefore baseline gets updated to the new rawcounts since other hardware parameters are fixed only Cp has changed.

In both the cases, when the hand is removed you will observe reduction in rawcounts level due to Cp decrease and baseline tracks the rawcount after low baseline reset timeout. You may not observe false triggers.

Please share us a video of the issue so that we can understand your issue better.

Regards,

Bragadeesh

Regards,
Bragadeesh

View solution in original post

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taas_3144281
Valued Contributor

Dear Bragadeesh-san

Thank you for your answer.

Sorry, My customer is worried at the development stage, so no problems have occurred.

Is it not necessary to consider the time during which the touch buttons must not be touched before turning on the power?

Best Regards,

Asanuma

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BragadeeshV
Moderator
Moderator

Hi taas_3144281​,

No, the customer need not be worried about the touch buttons not to be touched before turning on the power. Scanning doesn't happen till the system is powered and the CapSense_Scan is executed.

Regards,

Bragadeesh

Regards,
Bragadeesh
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taas_3144281
Valued Contributor

Dear Bragadeesh-san

Thank you for your answer.

I understood that there was no need to worry about not touching the touch buttons before turning on the power.

Is my understanding right?

Best Regards,

Asanuma

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BragadeeshV
Moderator
Moderator

Dear taas_3144281

Yes, you are correct.

Regards,

Bragadeesh

Regards,
Bragadeesh
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taas_3144281
Valued Contributor

Dear Bragadeesh-san

Thank you for your answer.

Best Regards,

Asanuma

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