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ADS1118: Configuration read back

Part Number: ADS1118

Hi Team,

Can you help with the inquiry below?

A customer is using the device for measuring two thermocouples as well as acquiring the chip temperature. The microcontroller communicates with this device via SPI and there are series resistors with all 4 interface pins, any one of those resistors failing in open circuit would not get detected. In order to detect such failure, the customer plans to verify by reading back the configuration word written or some other non-zero value. That way they would actually be able to acquire non-zero data validating that the interface is not broken. They cannot do that with normal commands since it is possible for both thermocouples and the chip temperature to all read zero degrees C values in normal operation, so in this situation, they would not know if they are actually all zeroes or if a connection is broken. The hardware is already designed and final, so the customer cannot change the hardware and they looking for a way to determine if the SPI bus CLK, MISO, MOSI, or CS are disconnected via firmware communications. Is there an undocumented command that would actually send back the configuration word written or some other command to get a fixed known test value? Or is there any other way?

Looking forward to hearing from you.



  • Hi Marvin,

    Yes, the ADS1118 offers the possibility of direct readback of the Config register settings in the same data transmission cycle if you use the 32-Bit Data Transmission Cycle.

    The data in a 32-bit data transmission cycle consists of four bytes: two bytes for the conversion result, and an additional two bytes for the Config Register read back.

    The Config register setting written in the first two bytes of a 32-bit transmission cycle is read back in the last two bytes of the same cycle.

    Please refer to section 9.5.7 of the data sheet for more detail.

    Best Regards,