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Demo LTC2497 with Raspberry Pi 4

Category: Hardware
Product Number: LTC2497

We are looking to demo the LTC2497 with a Raspberry Pi 4 as the I2C driver. The setup is as follows:

  • I2C bus connected to LTC2497 pins with pull up resistors (6.8k)
  • 5V power and GND to LTC2497
  • Address pins grounded (LOW, LOW, LOW)
  • REF+ at 5V, REF- at 0V

With this setup, we've only gotten as far as confirming that I2C is being queried using the RPi's `i2cdectect` tool, but we get no valid response. We have attempted to use different addresses, separate power supply, etc and no luck.

Other notes:

  • Other i2c devices work on the RPi bus no problem (detected and accessible)
  • Running the LTC2497 with the Analog Devices USB board and GUI software also works

The above lead me to believe that this is a wiring problem, but it is unclear where the problem could be.

I2cdetect on scope from Rpi (same result connected to LTC2497 or not)

I2cdetect not showing LTC2297, which is expected on address 0x14.

Any help is appreciated!

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  • Hello  ,

    It is possible that the device is sending a NAK a signal during a read operation (i2cdetect) while a conversion is on-going. Can you try writing something first before reading from a valid address? Write something like a Repeated Start command.

    Regards,

    Yugel

  • HI Yugel,

    Thanks for the response - we have verified that the I2C bus is set up with the i2c_bcm2708 driver (older) with the "combined" option, as had been suggested was required to enable repeated start, even when using i2cdetect. We had been following this user guide for setting up a Raspberry Pi config to read an LTC2497 chip.

    We have additionally just re-verified that other (possibly newer than LTC2497) i2c chips still respond on the bus we have set up.

    Thanks again - any further suggestions are greatly appreciated!

    Javier

Reply
  • HI Yugel,

    Thanks for the response - we have verified that the I2C bus is set up with the i2c_bcm2708 driver (older) with the "combined" option, as had been suggested was required to enable repeated start, even when using i2cdetect. We had been following this user guide for setting up a Raspberry Pi config to read an LTC2497 chip.

    We have additionally just re-verified that other (possibly newer than LTC2497) i2c chips still respond on the bus we have set up.

    Thanks again - any further suggestions are greatly appreciated!

    Javier

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