ADS1217: Can not read the converted data properly - I can read all the registers values correctly

sorry but what I meant is that "I can read all configuration registers properly"

Hi Fausto,

Can you send me the complete registers settings you are using? And can you send me your schematic? I would also be interested in seeing your communication as either logic analyzer or oscilloscope plots. I would monitor DRDY to make sure that your read after DRDY transitions from high to low state. Make sure that CS stays low throughout your entire communication transaction.

Best regards,
Bob B

Bob:

Thank you very much for your quick response

-Please find attached the ADC schematic

-The ADC interfaces with a microchip PIC32 microcontroller (PIC32MX795F512L-80V/PF) via a FPGA device

-The interface is a 8bit bus to SPI

-Polarity is set to falling edge

-What I am not clear is how do you read all channels in sequence ?? (if you have any code example of how to read channels in sequence please email me a copy)

- I can read all registers correctly evey time

-This is what I am doing:

only once after power up: Set Reg 0 = 0x0C : fosc/128 + Int VRef enable + Int Vref = 2.5V + buffer disable + most significant bit first (RA36 in the schematic is not installed, not ext VREF)

only once after power up: Set Reg 9 = 0x47 : Unipolar + auto settling

top:

Wait for "start conversion flag" from microcontroller

Set "adc busy flag" for micro

read channel"

set Reg 1 = channel number + 8 = AIN comm ( 0x51 + 0x00 + ch# + 1000b)

200ms delay

check if DRDY pin is low (data ready)

Read data 24b and store (0x01 than read 24 bits

clear "busy flag"

micro reads data

go back to "top"

Thank you again for your help

Fausto Bartra4527.ADC Sch.pdf

Bob:

Do you need a pull up resistor on DRDYn pin?

Thanks

Fausto

Bob"

I changed my code to monitor DRDYn falling edge
Before I was looking for DRDYn = low
DRDYn pin is always low. There is no short to ground
Do you need a pullup?

Thanks

Hi Fausto,

I have not finished going through all the material you sent previously. I did want to tell you that DRDY is an actively driven push-pull pin and is independent of CS. It does not require a pull-up. If you do not see this pin go high or toggle, then the ADC is not converting. Double check your RESET and DSYNC pin to make sure they are both high and that all your supplies are active and powering the ADS1217 at the device pins.

Also, make sure your crystal is oscillating. You have some very large capacitors on the crystal pins. These should be on the order of 10pF and not 1000pf.

Best regards,
Bob B