This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS1120 / can't access SPI I/F

Guru 29690 points
Other Parts Discussed in Thread: ADS1120, ADS1120-Q1
Hi Team,
 
My customer is evaluating ADS1120, however it seems that he can't access SPI I/F. 
So, I suggested him the following procedure(datasheet page.48). 
---------------------------------------
[Pseudo Code Example]
Power-up;
Delay;
Configure the SPI interface of the microcontroller to SPI mode 1 (CPOL = 0, CPHA = 1);
If the CS pin is not tied low permanently, configure the microcontroller GPIO connected to CS as an output;
Configure the microcontroller GPIO connected to the DRDY pin as an interrupt input;
Set CS to the device low;
Delay;
Send the RESET command (06h) to make sure the device is properly reset after power-up;
Write the respective register configuration with the WREG command (43h, 08h, 04h, 10h, and 00h);
Delay;
As a sanity check, read back all configuration registers with the RREG command (23h);
---------------------------------------
Could you tell me the required value of the "Delay" time?
 
Best regards,
Yaita / Japan disty
  • Hi Yaita-san,

    We anticipated this question and we have it included in the ADS1120-Q1 datasheet on page 46 (English version).  Unfortunately we have not yet had the opportunity to make these additions in the current ADS1120 datasheet.  See my responses below.

    One common mistake is with the use of CS.  CS must remain low throughout the entire communication transaction.  The raising and lowering of CS will reset the SPI communication, so the framing of CS must stay low until the complete communication of a multi-byte transaction (command/data sequence) has completed.  Many micro SPI peripherals will drive the SS pin in byte only frames.  It this case a GPIO function will be required if CS is to be used.  Of course CS can also be tied low if no other SPI device is connected to the bus.

    Best regards,

    Bob B

    KENSUKE YAITA said:
    Hi Team,
     
    My customer is evaluating ADS1120, however it seems that he can't access SPI I/F. 
    So, I suggested him the following procedure(datasheet page.48). 
    ---------------------------------------
    [Pseudo Code Example]
    Power-up;
    Delay; Wait at least 50us after supplies are at nominial voltage.
    Configure the SPI interface of the microcontroller to SPI mode 1 (CPOL = 0, CPHA = 1);
    If the CS pin is not tied low permanently, configure the microcontroller GPIO connected to CS as an output;
    Configure the microcontroller GPIO connected to the DRDY pin as an interrupt input;
    Set CS to the device low;
    Delay;Wait for a minimum of tCSSC (50ns)
    Send the RESET command (06h) to make sure the device is properly reset after power-up;
    Delay for a minimum of 50us + 32*tCLK
    Write the respective register configuration with the WREG command (43h, 08h, 04h, 10h, and 00h);
    Delay;Wait for a minimum of tSCCS (50nS)
    As a sanity check, read back all configuration registers with the RREG command (23h);
    ---------------------------------------
    Could you tell me the required value of the "Delay" time?
     
    Best regards,
    Yaita / Japan disty