ADS1256: ADS1256

Hi Sagar,

Can you help us understand what you have done to try to change the speed and how it has not worked? Have you made sure your ADC is communicating correctly? Have you tried reading back the registers to check if what you are sending is being received by the ADC? Have you tried changing other registers to see if they work i.e. is it only the data rate you are having trouble with or is it all registers? Are you getting any response from the ADC at all e.g. DRDY pulses?

It helps to provide step-by-step, detailed information on what you have done and what happens during your tests so we can help you diagnose the issue.

-Bryan

hello bryan ,

Yes bryan i change data rate in coding part into 2.5sps and i got 2-3 samples and similarly i made changes to get more number of samples and when i mention 1000 samples its 700-750 samples and again if i increase the data rate still its same. Next i changed  SPI max speed to 3840000 HZ  but no use.

here one more thing w i want to mention every time when i run the code once it can read 700 samples and once it can read 900 samples so i could not assume how much samples for different time of intervals when i run my code.

Hi Sagar,

Do you have logic analyzer to show us how the SPI communication is functioning? It would be very helpful to see how commands are being sent to the ADC and how the ADC is responding. This will not be obvious simply by looking at the code.

Are you watching for DRDY transitions (high to low) to know when new data is ready?

-Bryan

Hi bryan,

today i connected the DRDY pin to logic analyzer and DIN and i am DSO so only two channel can be connect at a time since when i run the code i got this and i can't able to find the data i available when DRDY pin at low.

1.Can you mention the basic steps which i need go follow in my code to read the data??

2.i got a doubt that my RPI is communicating with ADS1256 so i did loopback test to read and write a dummy data but here again i got doubt for loopback test i should connect MISO AND MOSI pins of RPI or RPI and ADS1256 MISO,MOSI pins ??

when i connect my DRDY and MISO to logic analyzer it gives me like this.

hello bryan,

i am using ADS1256 not ADS1256EVM and i followed the procedure which you have mentioned and if i change the sample rate it reads upto 1450 samples per second and but the reading data was not correct its a garbage value again if i choose lesss sample rate and less SPI speed then i can get proper values .

ok i will try to get proper waves in logic analyzer and i will update you .

regards,

sagar m

Hi Sagar,

Can you send me a picture of your board / setup?

-Bryan

Hi bryan,

this is my project set up and i gone through the datasheet and i have used input multiplexer MUX register mode to read the data 

1.i just write a loop to wait till DRDY pin goes low 

2. once DRDY pin is low and i write a register with respect to different channels for example 01h for AIN0,AIN1 and 23h for AIN2 &AIN3 ...etc.

3.then immediately i have sent SYNC and WAKE CMD to sync and i have delay 0.2ms then i sent RDATA CMD to read and put into buffer and which is returned by main loop so till i didn't get correct output and one time it will run and some time it failed to read the device ID itself.

Hello bryan ,

yes bryan still PCB in production so thats why i followed this way but its ok. But what  i followed the procedure points its right or wrong and should i  need to do some more things.

thank you so much bryan for your support and you very patience to answer any of my question that is really great.