How do I measure capacitance on PSOC1 LPKit?

[JeFe_286036]

Greetings

I have this PSOC1 low power kit from element14.  In that, the humidity sensor and a couple of capacitors as reference are configured on 3 port pins.

I am looking for example code which shows how this capacitances in the range 200-1000pf can be read.

Thank you

Jerson Fernandes

[Hari]

Hello JeFe_286036​

Is the requirement to read the capacitance value connected to the pin, or to measure the voltage at those pins?

Absolute capacitance measurement is not possible with the PSoC 1 for this range. If a constant value is connected, this can be tested by using a standard tool such as an LCR meter to measure the capacitance.

Best regards,
Hari

[JeFe_286036]

Hello Hari

If you see the schematic for the PSoC1 Low Power Development kit that is sold by element14, you will find the RH sensor connected on P1.2,  Cap_Hi reference of 470pf on P1.4 and Cap_Lo reference of 220pf on P1.6

Therefore, I have a strong feeling there must be some code example which shows how to use the connected sensor to find out the relative humidity value using the on board sensor and reference capacitors.

I wish to use the board with the thermistor and RH sensors for temperature and humidity measurements.

Thank you for your attention

Regards

Jerson Fernandes 

On Monday, July 20, 2020, 10:13:24 AM GMT+5:30, AH_96 <community-manager@cypress.com> wrote:

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How do I measure capacitance on PSOC1 LPKit?

reply from AH_96 in PSoC 1 MCU - View the full discussion

Hello JeFe_286036

Is the requirement to read the capacitance value connected to the pin, or to measure the voltage at those pins?

Absolute capacitance measurement is not possible with the PSoC 1 for this range. If a constant value is connected, this can be tested by using a standard tool such as an LCR meter to measure the capacitance.

Best regards,

Hari

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[Hari · Accepted solution]

Hi JeFe_286036​

This was mentioned in Element14 website:

We do not have a code example for this.

However, you can use a timer and a dac (or even a damped digital pulse) to measure the capacitance as the time to completely charge the capacitor increases with increase in capacitor. The two reference capacitors are provided to calibrate the value.

Best regards,

Hari