Kinetis Software Development KitのトピックRe: Using DbgConsole_GetChar()

Using DbgConsole_GetChar()

ashesman — Thu, 29 Sep 2016 00:34:05 GMT

Hi,

I use char c = DebugConsole_GetChar(); to read a serial character to simulate operation of a normally keypad driven menu system. I find that if I send two characters repeatedly, the GetChar function starts always returning 0 every call rather than blocking until a character is received.

I traced this through and it appears that in UART_ReadBlocking it checks the UART status (which has a RX buffer overrun flag set) and returns a kStatus_UART_RxHardwareOverrun. Which is ignored by the DbgConsole_Getchar function which happily returns the character 0.

Kind of frustrating. Mainly happens if I pause for debugging and send a character while paused by accident. So hardware is reporting a correct rx buffer overrun but does not seem to be cleared by the debug console code. Sometimes if I step through the code when it is stuck it will clear the flag and come right!

Any ideas???

Re: Using DbgConsole_GetChar()

jorge_a_vazquez — Mon, 03 Oct 2016 16:31:11 GMT

Hi Ashley Duncan

I confirm that this is a bug in SDK 2.0 driver, I have reported to development team an I will keep you informed for any update that they give me.

A possible workaround is check the return status of UART_ReadBlocking inside the DbgConsole_Getchar function, and return -1 if a error flag is set

int DbgConsole_Getchar(void)
{
    char ch;
    /* Do nothing if the debug UART is not initialized. */
    if (s_debugConsole.type == DEBUG_CONSOLE_DEVICE_TYPE_NONE)
    {
        return -1;
    }

    /* Modified */
    if( kStatus_Success != (s_debugConsole.ops.rx_union.GetChar(s_debugConsole.base, (uint8_t *)(&ch), 1)))
    {
         UART_ClearStatusFlags(s_debugConsole.base,  kUART_RxOverrunFlag |
                                                                 kUART_NoiseErrorFlag |
                                                                 kUART_FramingErrorFlag |
                                                                 kUART_ParityErrorFlag);
         return -1;
    }

  //  s_debugConsole.ops.rx_union.GetChar(s_debugConsole.base, (uint8_t *)(&ch), 1);

    return ch;
}‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Have a great day,
Jorge Alcala

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Re: Using DbgConsole_GetChar()

ashesman — Wed, 05 Oct 2016 01:53:44 GMT

Thanks for your help...

FYI see my other topic "How to disable SDK Debug Console" for another possible area requiring improvement. Assuming I have not missed something, you can not compile the SDK without the debug console which is a bit of a nuisance if you want to do your own serial handling.

Re: Using DbgConsole_GetChar()

ashesman — Wed, 05 Oct 2016 02:07:59 GMT

On a side note, the above fix can not quite work as GetChar is defined as:

void (*GetChar)(void *base, const uint8_t *buffer, size_t length);

Might need to be:

 /* Modified */
    if( kStatus_Success != (s_debugConsole.ops.rx_union.UART_GetChar(s_debugConsole.base, (uint8_t *)(&ch), 1)))
    {