• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Subscribers 81 subscribers
  • Views 635 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LaunchPad Application UART Speed

NJC
Intellectual 970 points


I was wondering if anyone knew the maximum speed supported by the LaunchPad on its Application UART? I can't seem to find it in the User Guide, but I could be missing it.

  • 0
    Intellectual 970 points

    9600 baud rate. I can't believe I missed it in the User Guide, and in section 1.1 at that.  Sorry for the stupid post.

  • 0
    TI__Expert 5240 points

    NJC,

    If you use the 2231 that comes with the Launchpad, it has a hardware USI/UART on the device.

    You can run this up to the maximum system clock frequency. If you enable the DCO and run it at full speed this would be 16MHZ.

     

    -Jason

     

  • 0 in reply to Jason Kriek
    Guru 58965 points

    Jason Kriek said:

    ... the 2231...  has a hardware USI/UART ...

    How does one utilize the hardware USI to function as an UART?

  • 0 in reply to old_cow_yellow
    Intellectual 970 points

    To clarify. I was asking about the Application UART, which is the UART on the LauchPad Emulator side, I was going to use it for simple data communication. I was not asking about the 2231, which does NOT have a hardware UART.

    OCY, to answer your question, one can not utilized the hardware USI as a UART. The USI can only be used for SPI and I2C.

    Hope that makes sense and clears things up.

    -NJC

    _____________________________

    http://msp430launchpad.blogspot.com

  • 0 in reply to NJC
    TI__Expert 5240 points

    NJC is correct, the G2 is only a USI and not a USCI.

    Some parts in the F2 family have the full USCI.

    Sorry for the confusion.

    -Jason

     

  • 0 in reply to Jason Kriek
    Guru 58965 points

    JNC,

    No problem. I understood you perfectly.

    Jason,

    That is okay. I was hoping that you have some way to utilize the USI to function as an UART.

    --OCY

  • 0 in reply to old_cow_yellow
    Guru 227245 points

    old cow yellow said:
    I was hoping that you have some way to utilize the USI to function as an UART.

    Yes you can :)
    At least for the TX side.
    YOu can set up the SPI for the desired bitspeed (it does not support clock modulation, so you'll need a bitclock that is a perfect multiple of the baudrate, or at least close enough).
    Then program the USI for 11 bit transfers (I think the USI supports up to 16 bits), attach a 0 bit as start bit first then the data byte and finally two 1 bits as stopbits (which will compensate if your block is slightly too fast) and send it out. No need to use the CLOCK and SOMI pin, but SIMO will send fine.
    It's not perfect but it reduces the CPU load for the timing when doing single-bit-banging instead.

    Same works for the USCI SPI if you need another UART on the B-module. Just that you'll need to generate 2 8-bit values and padd the 2nd databyte with another 5 1-bits (or mix-in the startbit and the first four bits of the next databyte). Not as painless as the normal UART but much less timing-critical than any software UART.
    And often, you need only one direction for debugging messages or such.

  • 0 in reply to Jens-Michael Gross
    Guru 58965 points

    Jens-Michael,

    Thanks for pointing that out.

    -- OCY

**Attention** This is a public forum