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MSP430FR5994: How to choose the communication rate of msp430fr5994

xi.yan.kiana
Intellectual 390 points
Part Number: MSP430FR5994

Hi,teams:

    I would like to ask, if you want to use the SPI module or UART module of MSP430, and the data reception adopts the interrupt reception method, is there any requirement for the communication rate? What should be the optimal recommended communication rate? 115200 or 9600 or...?

I encountered the following two cases of missing bytes：

    （1）The msp430 chip and other chip are used in my system. The communication method between the two chips is SPI communication,

and the communication rate is 2MHz. MSP430 is used as a slave to receive data, and the method is interrupt reception.

Since the main frequency of the msp430fr5994 system is 16MHz , resulting in the loss of bytes in the interrupt reception.

    (2) Using UART communication mode, the communication rate is set to 1MHz，There will also be byte loss.

Whether these two situations can be attributed to the fact that the main frequency of the MSP430 system is too low to respond and process interrupts quickly

I look forward to your reply, thank you

  • 0
    TI__Guru 68011 points

    Hi Xi,

    The MSP430FR5994 operating at 16MHz supports an asynchronous UART interface with baud rates from 9600 up to 230400 using interrupts.  Attempting to operate the UART at 1MHz or higher is possible, but may prove unreliable, mostly due to the difference in clock accuracy between the MSP430 and the other chip in your system.

    SPI, on the other hand, is a synchronous interface, which means the SPI controller (your other chip) generates the clock and the MSP430 peripheral uses that clock to synchronize the data coming in and out of the SPI peripheral so typically you can operate it at a faster rate.

    More than likely your data (byte) loss is due to not servicing the incoming data quickly enough and not necessarily the SPI or UART interface, considering you have data loss using either one.

    Can you tell me a little bit about the application and why you want to send data at fast rate?

    BTW - This baud rate calculator will be useful when you need to determine or verify your UART settings are correct.  Make sure you select the (EUSCI) and not (USCI).

  • 0
    Guru 22825 points

     With a MCLK of 16MHZ and SPI bit clock of 2MHz, that gives you 64 MCLK per received byte. This will require careful attention to the ISR to minimize the time taken.

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