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PSoC 4

MaLo_1836446
New Contributor II

Hello all,

I am using a PSoC 4 BLE Kit

CY8CKIT-042-BLE

I am doing a simple lab to teach my class about ADCs and Photo resistors and how to view the ADC result in putty.

mVolts=ADC_CountsTo_mVolts(0,ADC_GetResult16(0));

sprintf( output, "I am reading = %d mV \n", mVolts );

UART_UartPutString(output);

CyDelay(100);

I have everything working, however I noticed that my output was capped at 1024mV, I learned this was because on my ADC Block i had the VREF set at the 1.024 Volts ByPassed. I changed this to VDDA, which was set in the system at 3.3 but I was supplying it with 5. So when I programmed it, it capped out again at ~3000mV. So I went into the system and changed VDDD,VDDA,VDDR to 5V, now when I programmed it my values are off. When my multimeter reads about 700mV the PSOC reads about 1200mV, also when I shine a light on my photoresistor PSOC says it reads 5000mV when my multimeter reads about 4000mV. Is there some setting in the ADC SAR SEQ block I need to fix to get the accuracy back? or should I just power it with 3.3v which was just as accurate as the multimeter.

Thank you for your time in helping me

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1 Solution
Vasanth
Moderator
Moderator

Hi Charles,

Could you please check your VDDA value using the multimeter and give that value in CYDWR -> Systems tab . Normally it will not be exactly 5V. Please let me know the results after the change.

Best Regards,
VRS

View solution in original post

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2 Replies
Vasanth
Moderator
Moderator

Hi Charles,

Could you please check your VDDA value using the multimeter and give that value in CYDWR -> Systems tab . Normally it will not be exactly 5V. Please let me know the results after the change.

Best Regards,
VRS

View solution in original post

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MaLo_1836446
New Contributor II

Thank you that worked, I was using the 5V out on the programming board so I thought that would be the same as the VDDA, but measured the VDDA and it turned out to be 4.6V for this one. Again thank you it works as I want it to now.

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