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ADS7960: auto-1 mode

Lidong Yu
Intellectual 1756 points
Part Number: ADS7960

I have met some trouble when i set the function mode of ADS7960SDBT. According to the datasheet,
as my understanding, if i want the device work in auto-1 mode,i need firstly send [0010 1000 0100 0000 ]into sdi
to set the model control registers to make it work in auto-1 mode (2*Vref), and then send [1000 0000 0000 0000]
to enter autp-1 programming register,
finally send [0000 1111 1111 1111] to choose all the twelve channels.
But the device put out lots of nonsense ones and zeros, the first 4 number is not increasing from 0000 to 1100
i wonder the problems caused by my misunderstanding of the modes control method.
I also cannot understand the use of reset state in tabel 2 in page 36 of the datasheet. and after setting suceessful ,what number should i send next to make it work continuely

  • 0
    TI__Mastermind 22950 points

    Hi Lidong,

    The programming sequence looks right to me. Let me get ahold of an EVM and see if I can replicate the behavior you are seeing. 

    Additionally, can you also monitor the SPI transactions with either a scope or logic analyzer and share it's contents with me? I would like to see the SPI transactions. Also, is this done on an EVM or custom system? If not on an EVM, can you please share the schematic?

    Regards,

    Aaron Estrada

  • 0 in reply to Aaron Estrada
    TI__Intellectual 1756 points

     if you think my input is right，i will try  to find out whether the problem is caused by my codes. i have to finish other exam in these recent days, and i may give you other datas about a week later ( I
    don't save my output datas，they seems wrong. ). Before that, could you tell me if I set the device work in auto -1 successfully, what should I put in to keep the device work in auto-1 continually.
    To my understanding，the order as follows
    1、 input 0010 1000 0000 0000 to set modes register to auto-1 mode
    2、 start to programme auto-1 programme register 1000 0000 0000 0000

    3、choose channels 0000 1111 1111 1111

    4、now  just  constantly input 0010 0000 0000 0000 to keep it automatically work in auto-1 mode.

    after reading the datasheet again. I have another understanding，whether the DI10 in table 2 in page means if I set it 0, I don't need to set auto-1progamming register and the device will auto choose all the channels?  and what should constantly input next is 0010 0000 0000 0000  to make the device scan channel1 to  channel12 again and again .

  • 0 in reply to Lidong Yu
    TI__Mastermind 22950 points

    Hi Lidong,

    I got ahold of an EVM and double checked the commands you are sending and the order you are sending them it. I have confirmed that they are correct. I have attached a screenshot below and you can see that after writing 0x0FFF, you can see that the channel count starts at CH0 by checking the 4 MSBs. After that I am sending the configuration 0x2840 repeatedly and you can see the channel increasing. I ran this test with a 1.8V input on Ch. 8 and you can see that I am reading back 0x5C5 for this which is correct. 

    Bit D10 basically resets the channel count back to CH0. The screenshot also shows an example of this by writing 0x2C40 and then you can see the channel count reset to CH0 2 frames after applying the reset. 

    If you are sending 0x2000 repeatedly to scan the channels, then you are basically configuring the Auto 1 mode register to all 0's. That might be why are you not seeing correct data. You should send 0x2840 to scan the channels. Let me know if you are able to get things working.

    Regards,
    Aaron Estrada