How to use External Vref on PSOC 63 for both SAR and CTDAC in PSOC creator?

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jola_401441
Level 1
Level 1

Selected External Device Pin in the ADC component:

pastedImage_0.png

Selected External Vref Source with CTDAC

pastedImage_1.png

Selected Bandgap Value : External Pin (P9[7])

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The DAC appears to work fine, output range 0-1.250V with 1x gain.

The SAR ADC doesn't read anything other than 0x7FF. It does work if I use the internal 1.2V reference instead.

The pin P9[7] appears to be free, even though it should be assigned to External VREF.

pastedImage_3.png

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1 Solution
Vasanth
Moderator
Moderator
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250 sign-ins 500 solutions authored First question asked

Hi Jon,

I hope you are aware of the fact that external reference of SAR is given through the VREF pin, which is dedicated for it. The reference to the DAC is given as a buffered input through one of the opamps . Please let me know if this did not solve the problem.

Best Regards,
Vasanth

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3 Replies
jola_401441
Level 1
Level 1

Also shows up as unused in the Analog routing:

pastedImage_0.png

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Vasanth
Moderator
Moderator
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250 sign-ins 500 solutions authored First question asked

Hi Jon,

Could you please share your schematic too. If you can share your project that will be best for us to test. In PSoC Creator ,  go to File -> Create Workspace Bundle -> Select minimal. Please attach the generated file.

Additionally did you connect the ADC external reference to the VREF pin in of the chip in your design?

Best Regards,
Vasanth

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Vasanth
Moderator
Moderator
Moderator
250 sign-ins 500 solutions authored First question asked

Hi Jon,

I hope you are aware of the fact that external reference of SAR is given through the VREF pin, which is dedicated for it. The reference to the DAC is given as a buffered input through one of the opamps . Please let me know if this did not solve the problem.

Best Regards,
Vasanth

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