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MSP430F5438 - Total count of serial communication interfaces usable at same time

Josef Janda
Prodigy 230 points


Hi,

I am a little bit confused about total number of usable serial communication interfaces at the same time. In datasheet there is mentioned "Up to Four Universal Serial Communication Interfaces". But there are four for USCI_A and four for USCI_B. So there should be up to 8 independent USCI modules I suppose.

Are these statements right? I can use up to 8 USCI, but they cannot colide with their I/O pins. For example I use UCB0 as a master SPI, so i don't use at pin "P3.0/UCB0STE/UCA0CLK"  function UCB0STE-UCB0 slave enable. Can I use this pin as UCA0CLK? In better case.. UCA0 will be configured as UART - so i will not need this pin at all -I can use simultary UCSA0 and UCSB0.

It is might stupid question, but I need to project layout as sonn as possible. And I dont want to make stupid mistakes :).

Thanks, Josef

  • 0
    Guru 12160 points

    Hi Josef,

    You are correct that there are eight independent USCI modules.  Four of them are 'B' style (sync only) and the other four are 'A' style (async and sync).  You are also correct that the physical pins can sometimes limit your simultaneous use of the modules.

    Your example is also correct that you wouldn't use P3.0/UCB0STE/UCA0CLK for USCI purposes if UCB0 is a master SPI and UCA0 is UART.  In that case, you could use P3.0 as a simple digital I/O.  And yes, UCA0 and UCB0 are independent enough that they can run simultaneously.

    It's a bit confusing at first but it grows on you.  ;-)

    Jeff

  • 0 in reply to Jeff Tenney
    Guru 227245 points

    Jeff Tenney said:
    You are also correct that the physical pins can sometimes limit your simultaneous use of the modules.

    To be exact, if you use 4-wire SPI slave on one sub-module, the other sub-module cannot be a (full) SPI at all, because only 6 port pins are available per module and SPI slave requires 4 and normal SPI 3.
    I'm not sure what if the other SPI requires only 1 direction, maybe it's possible then too (check the pinout). Internally, it is not a problem, it's just the external port pin limitation.

    Any other combination of (SPI or UART) and (SPI or I2C) is no problem.

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