Reading some raw CapSense values result in constant values

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PoPr_2735541
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I'm using a CY8CKIT-059, with nothing connected to it other than the the USB on the KitProg and a micro USB cable for serial/UART/HID. I'm very new to PSOC in general. I'm simply trying to read the raw values from the CapSense sensors and printing them on the serial terminal.

I've set up my CapSense CSD like this, with everything else pretty much default, except for tuning to Manual:

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And here's is my main.c

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The problem is I'm getting sensor readings of 500+ constantly on the Generic2 (3rd sensor) & Generic3 (4th sensor), I sometimes got it to work by switching the pin mappings around, but sometimes the values switch from 500 to normal ranges every other data point. (I'm running my finger on the pads to show that Generic0 and Generic1 work normally here.)

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Thank you!

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Hi PoPr_2735541​,

It is not recommended to test CapSense performance without CapSense sensors (operation is not guaranteed). It is recommended to test CapSense only with sensor pads as described in PSoC 5 CapSense design guide (https://www.cypress.com/file/45441/download) for proper and reliable operation.

Regards,

Bragadeesh

Regards,
Bragadeesh

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BragadeeshV
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First question asked 1000 replies posted 750 replies posted

Hi popr_2735541​,

Welcome to PSoC world!

Can you please use the code example https://www.cypress.com/documentation/code-examples/ce95287-capsense-csd-using-tuner-psoc-35lp to observe the touch performance by Cypress provided debugging tool Tuner? Please let us know your observations.

1. Please check the connections between the sensor pad and PSoC GPIO pins.

2. Please probe the CapSense pins and check if you are observing charging and discharging waveform

3. Check if the CMOD and sensor pads are connected to the right pins in Design wide resources pins tab

4. Probe CMOD voltage and see if it at Vref.

If you are new to CapSense we recommend you to refer to the following application notes and code examples:

1. Getting started with CapSense

2. PSoC 5 CapSense design guide

3. Code examples

Regards,

Bragadeesh

Regards,
Bragadeesh
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Hi, thanks for the reply.

I've gone over all your concerns.

1. All the CapSense pins are not connected to anything right now, I'm just using the bare pins/header holes.

2. Previously, before I managed to fix it myself, the pins that reported 500+ constantly did not output any voltage, the working pins did indeed have a waveform on them.

3. & 4. CMOD is connected to 15[4] and I confirmed that they are at Vref.

Now, I have no idea why this works, but it does now. It would be great if anyone could help me understand why.

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And here's the scan order I ended up using:

pastedImage_1.png

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Hi PoPr_2735541​,

It is not recommended to test CapSense performance without CapSense sensors (operation is not guaranteed). It is recommended to test CapSense only with sensor pads as described in PSoC 5 CapSense design guide (https://www.cypress.com/file/45441/download) for proper and reliable operation.

Regards,

Bragadeesh

Regards,
Bragadeesh
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