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HELP, ADC of FRDM64 in differential mode

Question asked by hung lam on Aug 11, 2015
Latest reply on Aug 18, 2015 by hung lam

Hi all,

I have a problem with the ADC in differential mode. Let me explain my test settings: in order to verify the measurement of adc, I connect the internal DAC (output J4_11/DAC0 out) to the input of pin ADC0 (J4-1/ADC0_DP1) and the ground pin to the ADC0_DM1/J4-3. I program the board using kinetis design studio,  sdk 1.2/mqx standard and processor expert. The DAC works well, I have verified the output with the scope. However, the ADC also return always values ranging from 60,000 to 63,000 regardless of the DAC voltage output. The ADC is configured as followed:


16bit differential, bus clock as clock source, high speed mode, 1 extra ADCK cycle mode, no HW trigger, one-shot conversion, no DMA.


When I use the single 16bit mode, everything works just fine. But whenever I switch to the differential mode, I got the problem. PLEASE, HELP!!!!