UART sending loop on LCDK6748 with SYS/BIOS

Andres Vahter

I took example code from C:\Program Files\Texas Instruments\pdk_C6748_2_0_0_0\C6748_StarterWare_1_20_03_03\examples\lcdkC6748\uart\uartEcho.c

I would like to use the same code within SYS/BIOS project, so I converted this example into 2 functions: uart_init() and uart_tx().

uart_init() is basically the same as is main in this uartEcho.c example code. uart_tx() zeros counters and reenables interrupts.

In SYS/BIOS project I created a 1 s periodic clock where semaphore is posted. Semaphore is pending in a task where uart_tx() is called.

I am still new to SYS/BIOS so obviously I did something incorrectly, because I only see data on serial port once. I guess it is happening if uart_init() is called. I do not understand why it does not send data if I reenable interrupts within task.

I added this example code as github gist: https://gist.github.com/4621885

It would be very helpful if I could get some tips what to try out to solve this issue. I do not have JTAG yet, so I do not understand what is really happening. Probably some very trivial mistake.

Andres

over 12 years ago

0 RandyP over 12 years ago

TI__Guru* 84110 points

Andres,

My recommendations:

1. Get JTAG and CCS working.

2. Get the uartEcho example working as it is in the StarterWare example before trying to migrate to new code.

3. Study the SYS/BIOS training on the Wiki, searching for "sys/bios training" (no quotes).

Regards,
RandyP

0 Andres Vahter over 12 years ago in reply to RandyP

Intellectual 860 points

1. JTAG and CCS are now working

2. uartEcho is working

3. followed this: http://software-dl.ti.com/trainingTTO/trainingTTO_public_sw/bios/SYSBIOS_Workshop_Student_Guide_Rev6_67.pdf

I added breakpoint to line 122: https://gist.github.com/4621885

For some reason I did not catch this breakpoint. However it is printed to serial once if software is uploaded with flashloader.

Void tsk0Fxn(UArg arg0, UArg arg1)
{
uint32_t timeout;

uart_init();

 while (1)
 {
     timeout = Clock_getTimeout(clk);
     System_printf("timeout %ul\n", timeout);
     //Semaphore_pend(sem0, BIOS_WAIT_FOREVER);
     //uart_tx();
    Task_sleep(1000);
  }
}

I played more within this task and added breakpoint to Task_sleep.

It is working as expected if uart_init() is not called within task. However if it is called, Task_sleep seems to run forever.

0 Andres Vahter over 12 years ago in reply to Andres Vahter

Intellectual 860 points

It is going to make more sense to me.

With first try I completely ignored how HWIs should be setup in SYS/BIOS. So it is not possible to just copy-paste StarterWare examples to SYS/BIOS.

I rewrote it to use PSP UART driver instead of StarterWare: https://gist.github.com/4621885

Actually it is slightly modified uartSample_main.c taken from PSP examples.

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UART sending loop on LCDK6748 with SYS/BIOS