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What is the best TI Reference Design to use as the basis for my energy meter project?

Ashley Duddle
Prodigy 120 points
Other Parts Discussed in Thread: MSP430I2041, TIDM-TWOPHASEMETER-I2040, MSP430F6736

I am starting a new remote current monitoring product which has short timescales, so I wanted to start that design from one your reference designs.

The unit is an add-on to an existing piece of industrial equipment and the main requirement is to measure current into 3 seperate parts of the equipment.  Each of these are driven from one of the 3 incoming phases!

The new design has to connect to the equipment using current sense coils (3off); there will also be connection for a temperate sensor and some alarms.  The design also needs to support a GPRS modem for sending the data and receiving incoming request and configurations

The customer does not (at the moment) need a power measurement, just current - but we would like to add a voltage measurement anyway

Many thanks

Ashley 

  • 0
    Guru 46710 points
    Did you try to find reference design yourself? www.ti.com/.../refdesignsearchresults.tsp
  • 0 in reply to Ilmars
    Prodigy 120 points

    Yes, I did look through the summary and detailed descriptions and  www.ti.com/lit/ml/slyt541/slyt541.pdf 

    The low-cost 2-phase design uses an MSP430i2041 plus second processor.  IT has 4 A-Ds and I assume I could easily modify the design

    These polyphase designs looks suitable, www.ti.com/.../tidua02.pdf , www.ti.com/.../evm430-f6779, uses a single combined processor but is it more than I need.

    I only need to be able to monitor three currents and perhaps one voltage; will a polyphase design do that OK?  Also, what is the rationale for using two processors in some reference designs / EVMs but a single MSP430F67xx in other designs - is it cost, performance, or are they there to demonstrate different options?

    Regards

    Ashley

  • 0 in reply to Ashley Duddle
    Guru 46710 points

    >I only need to be able to monitor three currents and perhaps one voltage; will a polyphase design do that OK?
    Better modify single phase design - just copy/paste current measurement circuit & code.

    >Also, what is the rationale for using two processors in some reference designs
    Most probably those designs demonstrate low-end frontend microcontrollers, but reference design without display is not that good design. - That's why second microcontroller. IMHO. You can get away with msp430ixxx series and SPI OLED display. Perhaps.

  • 0 in reply to Ilmars
    Prodigy 120 points
    Thanks

    But I am struggling a little with the range of parts. As I understand the MSP430F676xx parts are designed for polyphase applications so are not really applicable for my multiple, single phase product, so I should look at the cheaper MSP430i20xx family which have 4 channels. In which case I will have a look a the reference design - Low-Cost Single/Dual-Phase Isolated Electricity Measurement Reference Design, TIDM-TWOPHASEMETER-I2040 and convert one of the voltage measurement channels into a current measurement one.

    Does that make sense, or can I one from the the MSP430F676xx series?

    Regards

    Ashley
  • 0 in reply to Ashley Duddle
    Guru 46710 points

    Indeed you can use MSP430F676xx series. - Because there' s no such thing as 3-phase msp430 :) They all can be used for either single phase or multiphase counters as long as particular chip have enough ADC's. Yes you can convert voltage channel to current channel because ADC will not mind this change, just software tweaking needed.

    The question is - why you have question. Do you think msp430ixxx will not be enough for what you are planning? Do you need display? Do you need isolation or data interface?

  • 0 in reply to Ashley Duddle
    Prodigy 120 points
    Sorry, looked again and perhaps this is a better starting point? Class 0.2 Single-Phase E-meter TIDM-SINGLE PHASE METER.

    It is is based on the MSP430F6736 device

    I could just enable another A-D channel and add more hardware

    Regards

    Ashley
  • 0 in reply to Ashley Duddle
    Guru 46710 points

    Ashley Duddle49 said:
    Sorry, looked again and perhaps this is a better starting point? Class 0.2 Single-Phase E-meter TIDM-SINGLE PHASE METER.

    Perhaps. As you do not tell details about need for display or isolated user/data interface - it is hard to tell.

  • 0 in reply to Ilmars
    Prodigy 120 points
    This design does not require a display, but would, ideally, run a web server to allow users to log into the device and view status and set parameters. It does need to control a GSM modem for sending and receiving data to/from a host.
  • 0 in reply to Ashley Duddle
    Guru 46710 points

    If you do not need display, then you do not need high pin count uC. Anyway you cannot run decent web server on any msp430, so you need low-end uC (i-series?) for metering and some ARM for webserver. I would go for http://www.ti.com/tool/TIDM-TWOPHASEMETER-I2040

  • 0 in reply to Ilmars
    Prodigy 120 points
    OK, many thanks. I will start with the cheaper MSP430i20xx family and base my design on something like the - Low-Cost Single/Dual-Phase Isolated Electricity Measurement Reference Design, TIDM-TWOPHASEMETER-I2040 reference design and add a processor that is suited to do the general processing and comms

    Thanks again for your help
  • 0 in reply to Ashley Duddle
    Prodigy 120 points
    I now have a board design based around this reference design and have downloaded the example software, but the app note says the software for talking SPI to a host controller is not implemented. Is there an update to the software that will support SPI from the MSP430i2041 to an external processor?
  • 0 in reply to Ashley Duddle
    Guru 46710 points

    If you got source code of both metering and host msp's, then implementing SPI code to transmit necessary data is not that hard. Anyway from now you shall look for TI official help/support/FAE

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