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ADS1259: Inappropriate response from chip.

randall veitch
Prodigy 190 points
Part Number: ADS1259


Hello,

As always, I breadboard new devices to make sure I understand how to use them before committing to a new design.

As a first communications test I attempt to read registers.  Using SPI, MODE1  MSB 1st., 1MHz.

I do not seem to be able to do this with the ADS1259 device.

I have tried different OP code combinations to no avail.

As an example, I have attached a typical screen shot of a register request (0x20) followed by OP code (0x01).

The Dout goes high as a response.  I expect to see a few zeros in the output for register 0 or register 1.

Have tried 1st OP codes 0x21, 0x22....2nd OP codes of 0x00,0x01,0x02.

As another approach, I did a "manual" implementation of SPI by assigning and manipulating IO pins to simulate SPI functionality.

(this usually helps if I am doing something wrong or if there is a timing problem with an SPI library.)

Still no response.

Any thoughts on what I may be doing wrong?

Thank you.

  • 0
    TI__Guru 53606 points

    Hi Randall,

    Some questions for you:

    • Have you ensured all power supplies are ramping to their full value, etc., upon startup and are connected properly?
    • Are you using the internal oscillator or an external clock?
    • Have you ensured that proper timing is followed from powerup to sending first commands as shown in Figure 49?
    • Have you tried sending the SDATAC after waiting the appropriate amount of time after start up? It is possible the device is in the RDATAC mode and will not respond to any commands until SDATAC is issued

    Communication issues could result from a variety of places in the ADC or in the surrounding system, so the more info you can provide the better we can help.

    -Bryan