Need help ADS1255

Hi Pradeep,

Welcome to the TI E2E Forums!

Regarding your Questions:

Pradeep Hegde said:

1.  Unable to read or write to register of ADC: I have referred the details in Page No 36 of the Data sheet regarding the reading and writing to registers in ADC, but I am not getting any error in program to read the data from register but I am not getting any valid data. It would be very help full if you provide with a sample code or verified working code to read/write data from the register. Help me to solve this issue.

I have a code snippet for the ADS1256 showing some of the order of operations:

while(P2IN&0x04);	                //Wait for DRDY LOW     

ads_cmd(1256_SDATAC, 0);	//SDATAC Command     
 
__delay_cycles(24);		        //DELAY     
					
ads_wreg(1256_ADCON, 0x20);	//WREG - ADCON     

 __delay_cycles(24);			//DELAY     
					
ads_wreg(1256_MUX, 0x45);	//WREG - MUX     

 __delay_cycles(24);			//DELAY     

ads_cmd(1256_SYNC, 0);		//SYNC     

__delay_cycles(24);			        //DELAY     

ads_cmd(1256_WAKEUP, 0);		//WAKEUP     

ch32_code=1256_drdy();		//READ After /DRDY     

Also check figure 19 in the datasheet for another example. Have you looked at the SPI communication on an oscilloscope to verify that your code is working as expected?

Pradeep Hegde said:

2.  Unable to verify output valid or not: I have made the connection as shown in the Datasheet pg no 28 and I am using continues read mode I am sending the read command only for the first time I run the program then I will only read DRDY I am able to read DRDY from the chip when that is low then only I am reading the data.   I have given my input analog voltage as 2 V if I capture the data out from the ADC I will get some data. Help me to solve the same.

I recommend getting the read and write register communication working first. If you haven't verified the SPI communication then you can't know if the problem is with the ADC or the SPI controller.

How are you applying the 2V signal? I assume that is the differential voltage, but you must also take care to reference the input voltage to the ADC correctly so that common-mode input voltage is not creating a problem. Do have schematic of your input connections that you can share?

Pradeep Hegde said:

3. How to make sure that chip is not spoiled during testing?

Monitor the supply current of the device while it is powered. If you see an abnormally high supply current outside of the data sheet specification, then it is likely an ESD cell was damaged.

Best Regards,
Chris

Hi Pradeep,

Please pardon the code segment above! I am having problems with it displaying correctly. There are multiple lines showing up on a single line.

-Chris