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ADS1298: No MISO Response From ADS1298 (SPI Communication Issue)

Part Number: ADS1298

Hi TI Team,

I hope you are all doing well.

I am working on interfacing the ADS1298 with my MCU and would like to understand the minimum required signals and conditions for successful SPI communication.

I’ve attached a screenshot of my schematic for reference.

At the moment, the following SPI signals look correct on the oscilloscope:

  • SPI_CLK

  • SPI_CS

  • SPI_MOSI

However, I am not receiving valid response from the ADS1298 on SPI_MISO(Always 0x00).

I have also attached oscilloscope captures of the RESET, START, and DRDY pins.

Additional details:

  • AVDD = 3.3 V

  • DVDD = 3.3 V

  • PWDN is pulled high to 3.3 V

  • External crystal is running at 2.048 MHz, confirmed on the scope

Could you please help me understand what the minimum requirements are for the ADS1298 to output valid SPI data, and what might cause the MISO line to remain inactive?

Any guidance or suggestions for debugging this issue would be greatly appreciated.

Thank you!

Schematic Connector:
ConnectorImage1.jpg

ADS1298 Schematic:ADS1298Image1.jpg

 

Waveform Startup Sequence:
ADS1298_StartUpSeq.png

 

Waveform ID Command:

ADS1298_ID_cmd.png