ADS1298 stops to generate DRDY signals

Luigi Nery

Hi,

Every time I run my code I send RESET command and stroble the CS pin to reset the serial interface. When I put the ADS in RDATAC mode it performs all conversions as expected to be, generates DRDY signals, all fine.

Then, suddenly the DRDY signal stops. While i can't find the problem, I need to reset the ADS config like when I power off and power on, because performing RESET command in initialization is not working.

Thanks,

over 9 years ago

0 Brian Pisani over 9 years ago

TI__Mastermind 38745 points

Hey Luigi,

Does anything else happen in code just before DRDY stops? Do you pull the START pin low for any reason?

Regards,
Brian Pisani

0 Luigi Nery over 9 years ago in reply to Brian Pisani

Prodigy 115 points

Nothing, just reading the conversion result. I don't have access to START pin, it is constantly high.

0 Brian Pisani over 9 years ago in reply to Luigi Nery

TI__Mastermind 38745 points

Hey Luigi,

Would you mind sending over a schematic?

Regards,
Brian Pisani

0 Luigi Nery over 9 years ago in reply to Brian Pisani

Prodigy 115 points

Brian,

unfortunately I can't, but I think the schema is correct. All works fine, but sometimes when started, after three or four seconds, ADS stops and a forced reset is necessary.

Do you have any idea what can generate this problem? What is the reason to stop conversions after START command? Any idea?

I think the unique way to stop the conversions is to sending SDATAC or STOP command.

0 Brian Pisani over 9 years ago in reply to Luigi Nery

TI__Mastermind 38745 points

Hey Luigi,

This is not a problem I have ever encountered before and is definitely not typical behavior for the device to stop converting intermittently.

Sending the SDATAC command will not stop conversions, it just stops the data from automatically shifting out with SCLK. The STOP command is the only command that would cause the converter to halt.

If you feel more comfortable, you can send the schematics to pa_deltasigma_apps@ti.com so that it's not on the forum.

Regards,
Brian Pisani

0 Luigi Nery over 9 years ago in reply to Brian Pisani

Prodigy 115 points

I found a controlable behavior in this intermittent problem. I'm doing the tests in low power mode at 1kSPS and when configured to 500SPS works perfectly.

0 Brian Pisani over 9 years ago in reply to Luigi Nery

TI__Mastermind 38745 points

Luigi,

Are you saying that it works at some data rates but fails at others? That is very peculiar indeed.

Regards,
Brian Pisani

0 Luigi Nery over 9 years ago in reply to Brian Pisani

Prodigy 115 points

Brian,

what happen if while i'm reading ADS the conversion results and a DRDY notification occurs and so, I start to read again the ADS before all remaining 27 bytes been readed previously? This procedure can cause any unexpected behavior?

0 Luigi Nery over 9 years ago in reply to Brian Pisani

Prodigy 115 points

I think I found a situation that is not directly associated with sample rate. I think when a "break" the last conversion package cause some unexpected behavior. See my last reply.

0 Brian Pisani over 9 years ago in reply to Luigi Nery

TI__Mastermind 38745 points

Hey Luigi,

It makes sense that you would miss a sample if you took too long to collect the previous one (I have seen this issue fairly often), but I do not expect the ADC to stop converting.

Brian

Data converters

Data converters forum

ADS1298 stops to generate DRDY signals