• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 30 subscribers
  • Views 1908 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.

Tiva C Connected Launchpad (TM4C1294NCPDT) UART Communication

Okan Kucuktopcu
Prodigy 110 points


Hello,

I have just realized that the UART modules does not work correctly when I want to communicate with PC by debug port on Launchpad. I can use UART0 correctly and UART2 with PD4 and PD5 as Rx and Tx respectively by changing the JP4 and JP5 as CAN communication. 

However, I couldn't use the rest of the UART modules (UART1, UART3, UART5, UART6, UART7) by Debug USB port. In addition, In the online PinMux utility, I've realized that some UART modules (U1, U2, U3, U4) uses multiple couples for Rx and Tx. For Example, U3 uses PA4 and PA5 as Rx and Tx; and also uses PJ0 and PJ1 as Rx and Tx.

My questions are,

1 - Can I use all the UART modules on Launchpad to communicate with PC by Debug USB port. If I can, which configurations do I use? I'm doing all the configurations as same as UART0 configuration. I'm changing only the pin configurations for different UART modules.

2 - For the UART modules that have multiple couples for Rx and Tx, which couple should I use? Can I use whatever I want to use?

Thanks for your replies. 

  • 0
    Guru 11940 points

    1 - Can I use all the UART modules on Launchpad to communicate with PC by Debug USB port. If I can, which configurations do I use? I'm doing all the configurations as same as UART0 configuration. I'm changing only the pin configurations for different UART modules.

    No, you can't.

    Take a look at the schematics, and think about it again.

    Only UART0 is routed to debug pod on the Launchpad, which "translates" the UART data into USB - hence the name VCP (Virtual COM Port). If you want to use VCP, you must use UART0. This VCP port is for convenience, to have debug output output without an additional connection/cable. This question had been asked (and answered) just a few days ago here.

    2 - For the UART modules that have multiple couples for Rx and Tx, which couple should I use? Can I use whatever I want to use?

    Yes, whichever you like, and which is free/usable. Pin multiplexing is a common method to bridge the conflicting requirements of having many different peripherals, but a limited amount of package pins. Often, other pins are reserved for project-important peripherals (PWM, ADC, etc.), and you need to "evade" to other, remaining pins for "secondary" functions like debug output. However, pin multiplexing always adds complexity.