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# PSoC 5, 3 & 1 MCU

New Contributor II

## DAC ADC problem

I have a problem with my ADC-DAC.I create voltage with the ADC and print it on the LCD screen. I do this with the help of the variable i.The value i goes from 0 to the max value of DAC. The value selected in DAC is 0- 4.080V (1mV / bit)

i is rising up to 4080. but when I measure the voltage at the pin with the voltmeter, it varies from 0 to 3.15V (for example i = 0 ==> voltage = 0V, i = 4080 ==> voltage = 3.15V)

Does the voltmeter measure the value of 4.080V? How to fix this.

I want to measure the voltage on the resistor connected to the voltage divider with the DAC.but I can't see the voltage here on the lcd screen.

1 Solution
Moderator

## Re: DAC ADC problem

Hello Burak,

Could you please check your VDDA voltage? The output voltage is actually VDDA-Compliance voltage. Where compliance voltage comes around ~1V. So if VDDA is 5V you will get 4.08V as the maximum output. But if the VDDA is a lesser value, the range also reduces accordingly. Please check the VDDA voltage in your system using a multi-meter and confirm this first.

Best Regards,
Vasanth

2 Replies
Moderator

## Re: DAC ADC problem

Hello Burak,

Could you please check your VDDA voltage? The output voltage is actually VDDA-Compliance voltage. Where compliance voltage comes around ~1V. So if VDDA is 5V you will get 4.08V as the maximum output. But if the VDDA is a lesser value, the range also reduces accordingly. Please check the VDDA voltage in your system using a multi-meter and confirm this first.

Best Regards,
Vasanth

Honored Contributor II