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MSP430FR6047: Muxing and pin connections w/ external amp

Barrett Bryan
Intellectual 1010 points

Part Number: MSP430FR6047
Other Parts Discussed in Thread: EVM430-FR6043, TIDM-02003, OPA838

I'm working on schematic for flow meter with MSP430 directly driving transducers for TX and external amp added to RX path. Are there any problems with the configuration illustrated below?

externalAmp.TSC

  • 0
    TI__Expert 7415 points

    Hi Barrett,

    You can look at the schematics for the EVM430-FR6043 (http://www.ti.com/tool/EVM430-FR6043). This is the schematic for TIDM-02003 at http://www.ti.com/lit/pdf/tidrys5. 

    This addresses the configuration you are trying to achieve with an external amplifier (OPA838) on the receive path while directly driving the transducers on the excitation (TX) path.
    The relevant section on the schematic is on sheet 3.

    Srinivas

  • 0 in reply to Srinivas Lingam
    TI__Intellectual 1010 points

    Hi Srinivas,

    Thanks for highlighting where to find this circuit. You'll notice my component values match up with this circuit since I mostly copied it. I had a few issues with this circuit though--I'm hoping you can help me understand a few things so I can more accurately modify this based on requirements.

    • VCC for TX and RX will be the same for this design, so I don't see the need for additional buffer. Would this allow me to reduce to single 2:1 / SPDT mux as illustrated in my circuit?
    • The RX path from the circuit you referenced returns to single channel--CH0. Can I connect output to both CHx inputs instead to avoid having to change software for the flow sensing routine?

  • 0 in reply to Barrett Bryan
    TI__Expert 7415 points

    Hi Barrett,

    • If you don't need the 5V excitation and can operate both TX & RX at 3.3 V, you should be able to replace it with a single mux.
    • I don't understand how you can connect the RX path to both CHx inputs. If you do that, it will be equivalent to shorting it to the TX path. I don't think this should be done. Also, modifying the SW is pretty straightforward.

    Srinivas

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