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DAC61416: How can read DEVICEID in daisy chain mode?

Sindy Fl
Prodigy 10 points
Part Number: DAC61416
Other Parts Discussed in Thread: DAC81416

Tool/software:

Dear TI engineer,
Hello, my question is whether the SPI daisy chain method of multiple DAC61416 chips can read DEVICEID?
Currently, we need to connect 3~6 DAC61416 chips using daisy chain. I am sure this can be done using write operations, as mentioned in the specification sheet(8.5 Programming
..... The interface provides access to the DACx1416 registers and can be configured to daisy-chain multiple devices for write operations. .... ),

but I also want to  read some register information like deviceid or status . Does daisy chain support read operations? How to operate if supported?

Thank you and Best regards

Sindy

  • 0
    TI__Expert 3530 points

    Hi Sindy,
     
    SDO for DAC81416 would be used as SDI for next DAC81416 while using the daisy the chain operation. That implies you wouldn't be able to able access the SPO pin except for the last DAC81416 . 
     
    Hope that clarifies your query. 
      
    Thanks,
    Sanjay

  • 0 in reply to Sanjay
    Prodigy 10 points

    Sanjay, 

    Thanks for your reply quickly.    
    I understand what you said about SDO SDI cascade,   like this ,  MCU.MOSI->CHIP1_DAC61416_DIN - >CHIP1_DAC61416_DOUT = CHIP2_DAC61416_DIN -> CHIP2_DAC61416_DOUT = CHIP3_DAC61416_DIN  -> CHI3_DAC61416_DOUT - > MCU.MISO  
    but my question is whether it is possible to use an instruction to read the status register of the first DAC chip and pass its return value all the way to the last DAC in this cascade, Can the MCU receive the information from the DOUT pin to the MISO of the MCU?

    in the specification sheet PAGE29 (8.5 Programming
    ..... The interface provides access to the DACx1416 registers and can be configured to daisy-chain multiple devices for write operations. .... ),

     

    So simply put, my question is whether it is possible to perform read operations in the case of multiple devices in a daisy chain?

    Thank you 

    Sindy

  • 0 in reply to Sindy Fl
    TI__Expert 3530 points

    Hi Sindy,
     
    Now I understood your question properly.
    And yes it's possible to read the register for any device in daisy-chain mode. 
     

    For read you need pass the the read command with frame length N x 24 and then NOP with same frame length N x 24 to fetch the data on last available SDO pin. Later you need to decode the the data to get the read back values for individual DAC devices.
     
    So yes,  it is possible to perform read operations in the case of multiple devices in a daisy chain.  

    Thanks,
    Sanjay 

  • +1 in reply to Sanjay
    Prodigy 10 points

    Sanjay,

    Thank you .  I got it and will try it when the hardware is ready.  

    Thanks again and Best Regards

    Sindy