RTOS/TM4C1294NCPDT: Only one UART index can be used at a time..

Robert Cram

Part Number: TM4C1294NCPDT

Tool/software: TI-RTOS

the TI RTOS 2.20 user guide says of the UART driver, "...Only one UART index can be used at a time. If the index is already in use, the driver returns NULL and logs a warning.."

What does this mean? It's not clear what it means: Read() or write() can only be called on one instance at a time? The second sentence sounds like it's saying that an Index can only be used by one instance at a time, which is different. I'm trying to understand what the restrictions are, as I'd like to read and write from multiple UARTs at a time (which seems like the point of having multiple UARTs available).

I will appreciate any advice.

- Bob

over 7 years ago

0 ToddMullanix over 7 years ago

TI__Guru* 96960 points

Hi Robert,

It means you cannot call open twice with the same index (without closing inbetween). For example

handle1 = UART_open(0, ...);
handle2 = UART_open(0, ...); //this will fail since it is already open.

We did this to reduce the amount of code to handle the resource management of multiple opens on the same index.

Todd

0 Robert Cram over 7 years ago in reply to ToddMullanix

Intellectual 545 points

Thank you. I suspected (and certainly hoped) it was something like that. I think the wording in the documentation is unclear.

- Bob

Arm-based microcontrollers

Arm-based microcontrollers forum

RTOS/TM4C1294NCPDT: Only one UART index can be used at a time..