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I (Micah Black will hard-code some more stuff while Gerald Aryeetey (Deactivated) looks in to a fix for this.
Updates Jun 10, 2020
We fixed the PEC and the correct order for the COMM register data bits.
With those fizes, we got communication happening over the external SPI port to theMUX. Still not getting any useable data from it though (all ~2.1V for the measured channels - they should be around 1.5V or below according to the the calculations above.
I really wish this board had better test points for all of the communication outputs - but that’s beside the point.
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The mux datasheet mentions that the data should be clocked in the to serial input MSB-first, and the LTC6811 datasheet mentions that all data transfers happen MSB first, so we should be good on that front.
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I noticed this seemingly weird behavior of the 3V0_VREF2 pin measured at the input to the buffer. The device turns on, takes 12 temperature measurements, then goes back to sleep. It seems the 3V0_VREF2 is going to sleep between every AUX measurement. The period between the dips in 3V0 lines up with what I'm seeing on the logic analyzer for the read AUX commands, roughly a 13mS period (note I had slowed down the SPI communication for this to get a better visual of the external SPI port on the scope earlier, and the 13mS period will not be what is in the car). Liam Hawkins Is this expected behavior? Should the references be powering off? Sleep transition takes 2s, and the Green LED for 5V0 indicating DRIVE is always on, so the IC seems to be going in to STANDBY state.
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