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CCS/MSP432P401R: How to use multi-channel of digital communication?

Yu-Hung
Expert 1130 points

Part Number: MSP432P401R

Tool/software: Code Composer Studio

Hi,

I would like to use MSP432P401R to read data from 10 sensors.

In outdoor application, there are many waterproof cases and connectors and the distance between sensors and MSP432 is 1 or 2 meters.

So, I don't want the MSP432 to read analog data directly.

This is hard for me to do calibration.

I think the digital communication is the better way.

First, I think I can use 4 hardware UART->RS232 and 6 software I/O->RS232 to read sensor data.

But I don't know is it suitable?

Second, I think I can use RS485 for multiple communication.

But I worry that one of sensor is broken then make the communication suspended.

Has someone know how to do?

Any suggestions will be appreciated.

YHH

  • 0
    TI__Mastermind 25045 points
    Hello YHH,

    Could you please share more information on the sensors that you are planning to use?

    Thanks,

    David
  • 0 in reply to DavidL
    Expert 1130 points

    Hi David,

    I use meteo-sensors like wind , temperature and pressure sensor.

    Most of them are analog output.

    Some are RS232 output like GPS.

    Because they setup at outdoor (long cable and more connectors), maybe effect the accuracy of A/D conversion.

    So I would like to convert to digital output in sensor side.

    I don't know what kind of digital output is good for this application.

    My first idea is use RS232, but there is only 4 hardware UART in MSP432.

    It means I have to design 6 software UART by I/O.

    I don't know so much software UART are good or not.

    YHH

  • 0 in reply to Yu-Hung
    Guru 74080 points
    Hi Yu-Hung!

    If there is no analog to digital conversion implemented yet and you are planning to do this yourself, then why not make small slave boards that each read a sensor, convert the data to digital and send the data on request of the master (the MSP432 in your case). You could use one single RS232 line, for example. Every device listens on the bus but remains in high impedance mode as long as it did not receive his specific request to send data. Then the addressed device switches over to control the data line and sends it's data. Like it is done for I²C. You can also use SPI and I²C for distances of 1 or 2 meters when operating at low transmission speeds, but surely these busses are not made for long distance communications. RS485 would be possible as well, of course.

    Dennis
  • 0 in reply to Dennis Eichmann
    Expert 1130 points

    Hi Dennis,

    This is very similar to RS485. (one master and multiple slave)

    The problem is that all sensor are connecting together.

    If one of them is broken, the output maybe short circuited or keep in low/high level.

    e.g. water get into the waterproof case, this is always happen. (by Murphy's Law)

    This is my concern.

    YHH

  • 0 in reply to Yu-Hung
    Guru 74080 points
    Yes, sure - if something is broken you cannot expect proper operation. So this is why you want to use an individual connection to every slave? You could also think about a multiplexer if there are not enough hardware modules available.

    Dennis
  • 0 in reply to Dennis Eichmann
    Expert 1130 points
    Yes, you are right.
    I am looking for TI solution to get more UART/RS232.
    :)

    YHH

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