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AD7606: Inconsistent output value

Question asked by simba on Aug 14, 2014
Latest reply on Aug 20, 2014 by r.daemon@tugraz.at

Hi,

I am using AD7606 eval board & have interfaced it with a Arduino [intel galileo] board.

I have written a test program to verify the hardware[before going ahead and adding as linux driver], I see inconsistency in the output code values.

 

I connect channel 1 to a constant supply voltage, following output code value range is what is being seen on the serial output console.

 

SlVoltage ValueOutput Code Range
1+5V29000 ~ 61000
20V0 ~ 30000
3-5V0 ~ 30000

 

I have hard wired

1. Range & Stbl pin to Vdrive,

2. Grounded OS0~2.

3. Grounded Data lines D0 ~ D6, D9 ~ D15.

4. Removed R3 & connected R4. [Converting parallel to serial mode.]

 

I have applied a RESET pulse of 1 micro sec [min available in arduino boards], at the start.

I have connected BUSY signal to interrupt pin, & I am doing chip select & SPI read operations inside the ISR.

 

I have attached 2 images of the timing diagram

 

Image 1:

Ch2: Blue:    CONVST signal

Ch1: Yellow: BUSY

Ch3: Pink:    ~CS

Ch4: Green   DoutA / MISO

ADC_Timing_CS.jpg

 

 

Image 2:

Ch2: Blue:    CONVST signal

Ch1: Yellow: BUSY

Ch3: Pink:    FirstData

Ch4: Green   DoutA / MISO

 

ADC_Timings_FRST.jpg

Please let me know how I can debug this issue.

 

Regards

Simba

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