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ADS1298ECGFE-PDK: Not able to read Device ID with external micro-controller of ADS1298

Ajay Rathor
Prodigy 70 points
Part Number: ADS1298ECGFE-PDK
Other Parts Discussed in Thread: ADS1298

Tool/software:

Hello,
I'm using an ADS1298ECGFE-PKD evolution board. when I use the evolution kit with ADS1298 software, I can read device IDs and obtain data. As you can see in the image below,

However, as you can see in the image below, I am unable to read the device ID when I disconnect the MMB0 mother board and connect the Ads1298 to the Arduino Uno.

The jumper and pin settings are as follows:
3.3V to J4.9,
5.5V to J4.10,
GND to J4.6,
CS to J3.7,
SCLK to J3.3,
DIN to J3.11,
DOUT to J3.13,
DRDYD to J3.17,
RESET to J3.8
JP2 = 1-2,
JP20 = 2-3,
JP15 = 1-2,
JP24 = 2-3,
JP18 = 2-3,
JP19 = 1-2,
JP21 = 2-3,
JP22 = 2-3,
JP23 = 1-2.

I have verified the voltage at VCAP1 = 1.16V ,VCAP2 = 2.40V ,VCAP3 = 6.8V and VCAP4 = 0.18V. Is everything in our connections are okay? What actions are required to read the device ID of ads1298?

  • 0
    TI__Guru 64236 points

    Hi Ajay,

    I noted a couple mistakes in your connections above (perhaps they are just typos). Please recheck the following:

    • GND should connect to J4.5
    • nDRDY should connect to J3.15

    What is your SCLK frequency when using the Arduino? Have you met the tSDECODE requirement?

    Also, after power up and master CLK is enabled, it's important to give a pulse on the reset pin. Have you followed the procedure outlined in section 11.1?

    Regards,

    Ryan

  • 0 in reply to Ryan Andrews
    Prodigy 70 points

    Hi Ryan,

                   nDRDY is connect to J3.15 only that was my typing mistake, As you said connect J4.5 with ground but J4.5 is already connected with ground and J4.6(AGND) it is not connected to ground i am connecting it to ground.

     I'm following all of your instructions as you mentioned above, but when we measure the ADS1298 + mmb0 board, we observed some data on the CRO spi_clock and spi_MOSI/MISO pins of our ads1298 board are operating at 3.3 and 1.8 volts, respectively. This is shown in the image below.

    YELLOW : MISO ,BLUE :  MOSI and PINK : CLOCK

    and this is what we saw when we connected Ads1298 + MCU; you can see it in the image below.

    YELLOW : MISO ,BLUE :  MOSI and PINK : CLOCK

    Due to the fact that our ADS1298 board is not functioning on 3.3V, we have connected JP24 with 1-2. Is this happening because we change that jumper JP24 or anything else?

  • 0 in reply to Ajay Rathor
    TI__Guru 64236 points

    Hi Ajay,

    Thanks for pointing this out. It looks like the MMB0 is using 3.3 V I/O supply, independent of the DVDD setting on the EVM (JP24). I'll have to check later today if the digital outputs from the ADS1298 are being level-shifted properly on the MMB0.

    When using the Arduino, it will be important to use the same I/O levels on both boards. If you set JP24 in the [1-2] position, where is the 1.8-V supply coming from? Are you connecting 1.8V from the Arduino board to TP9 (or J4.7)?

    Regards,

    Ryan

  • 0 in reply to Ryan Andrews
    Prodigy 70 points

    Hi Ryan,
    We are giving 1.8V from DC Power supply and connecting it to J4.7 pin of ADS1298. As you said when using MCU, it is important to use the same I/O levels on both the board, we have already used level sifter between both the boards.

  • 0 in reply to Ajay Rathor
    TI__Guru 64236 points

    Hello Ajay - have you been able to resolve this issue? Are there any other devices loading the same SPI bus? I don't see why the MISO line should be loaded such that it cannot fully reach the logic high levels, especially since the ADS1298 and MCU are sharing the same supplies. It also looks like the SCLK waveform is affected as well since it is not quite reaching 3V.

    Regards,

    Ryan