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MSP430F6736: extending ref design TIDA-00879 to measure resistance using onboard sigma-delta ADC

Part Number: MSP430F6736
Other Parts Discussed in Thread: OPA333

Tool/software:

From the detailed ref design, we can see how to implement V, I measurements. From the schematic block diagram (Figure 1) we see V mode and I mode sensor data is fed to a programmable gain amplifier / ADC chain in the MCU . From the MCU datasheet, it is seen that V+/V- outputs from an OPA333 op-amp is fed to MCU pins SD0P0/SD0N0 and I+/I- outputs from a similar op-amp is fed to pins SD1P0/SD2P0. It is noted that that SD24_B is a multiple-input multiple-converter sigma-delta analog-to-digital conversion module. There are possibly 0-7 (eight) such modules, in the TIDA ref design, SD2P0/SD2N0 are shown tied to ground and the rest of the input pairs not shown.

  1. I would like to implement a resistance measuring function. Is there an application note relevant to this design for this function? A DMM is kind of useful when it can measure V, I, R on the bench.
  2. Is it recommended to implement a separate R measurement front end and feed it into the SD24_B ?
  3. Is it possible to use existing V, I sensor telemetry to calculate R at all in this ref design without additional elements?
  4. If a separate R measurement front end has to be designed, are there any COTS semiconductor elements available from TI ?
  5. Given existing ref design, if simultaneous V, I measurements are possible (are they?) is there a suggested design methodology to design a four-wire Kelvin Method resistance measurement feature?

Can we obtain a development kit that already has the MCU pinned, and SD24_B pinned for an experiment? 

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