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ADS1293: DRDYB doesn´t assert

Luis Trejo
Prodigy 90 points
Part Number: ADS1293
Other Parts Discussed in Thread: MSP430FR5738,

Hi everyone.

I need your help for this issue. I am designing a project using ADS1293 and the MSP430FR5738. I am using SPI interface to comunnicate both ICs. At first time, it was working good, giving me the data from the 3 ECG channels, but then,  the ADS stopped working. I don´t believe the problem was the comunnication because there is a routine where the MSP reads the registers that were written and all ot them are good. I replaced the oscillator crystal but  the problem persists. Also I monitored the voltage at DRDYB and the voltage is always 3.3 - 3.5 V. This voltage is because the pull up internal resistor is enable.

What would be the cause of this problem? is it posible that the DRDYB pin is damaged?

I will be gratefull for an answer.

Best regards.

  • 0
    TI__Genius 11550 points

    Hi Luis,

    Thanks for the post.

    Have you changed anything (software or hardware) from the initial testing where the ADS1293 is operating normally? If all the power supplies are normal, and the device register read and write operation is working, then there may be an issue with the device itself. You may want to replace the ADS1293 and check to see if it resolves your issue.

    Thanks

    -TC

  • 0 in reply to TCT
    Prodigy 90 points

    Hello TC, and thanks for your response.

    I checked if the read and write operation is working and it is, I write on a register any value and then read it to verify and it´s working good, in fact, the SPI and UART interface are worrking good. I changed the oscilator crystal because I thought that was the problem but it didn´t changed something. At first time I was debugging the MSP430 using Spy Bi-Wire interface from a Launchpad development kit. The voltaje output from Launchpad is 3.5 V; in the ADS1293 data sheet, the Digital I/O Supply Max Voltage is 3.6V I don´t tnink if this level would damage the DRDYB pin from ADS1293 because I can read/write on any register. Also I read the values from registers 0x19 - 0x1E (refering to the error status registers) after program the ADS1293 to read the 3 Channels and I got values of 0xFF in those registers.

    So, could the ADS1293 be damaged?

    Regards.

  • 0 in reply to Luis Trejo
    TI__Genius 11550 points

    Hi Luis,

    I agree with you that the voltage level should not damage the DRDYB pin. Can you verify that all the analog and digital power supplies are in normal operating conditions? Please also measure the CVREF pin to make sure the internal reference voltage is 2.4V. There is definitely some issue with the device as you are getting errors for all the Error Status Registers. I suggest going back to the original program and ensuring all the registers are set correctly, and no errors occur for all the Error Status Register.

    Thanks

    -TC 

  • 0 in reply to TCT
    Prodigy 90 points

    Hi TC.

    I checked the CVREF and it´s 2.4 V, also I checked the analog and digital power suplies when the launchpad is conected and the voltages for VDD and VDDIO are 3.4 V. I checked again the registers and all of them are okey. I don´t know if I am writting the wrong values for this project, I used the register values from the Typical Application: 3-lead ECG Application but I added some registers and changed some values.

  • +1 in reply to Luis Trejo
    TI__Genius 11550 points

    Hi Luis,

    As suggested, can you revert to your original program where you are able to get meaningful ECG signals with the device? Also, please send the full device register settings for our reference. Can you verify that DRDY is operational or consistently stuck at HIGH with only a pullup resistor and not connected to the MSP430?

    Thanks

    -TC

  • 0 in reply to TCT
    Prodigy 90 points

    Hi TC.

    You were right!!!

    There was something wrong in the MSP430 programming, to be more accurate, in P1SEL0 and P1SEL1 to program the secondary function for the SPI Interface. The corious thing was the routine that I had made to verify each register told me that it was programmed well, but then I read some of the registers and the value that I got was 0xFF, then I go back to the original SPI test program (where I can read the correct value) and check the code, that was the little problem.

    Thank you so much for your help.

    Wishing all the best.

    And the best regards.