ChibiOS Free Embedded RTOS

Posted: **Wed Feb 03, 2021 9:39 pm**

Per the below link I see the non-blocking function sdWriteTimeout. However I see that chprintf uses sdWrite and I do not see any version of chprintf which includes the sdWriteTimeout variant.
https://www.playembedded.org/blog/stm32 ... os-serial/

Am I correct that there is no chprintf (or equivalent) function with timeout? If it does not exist, then I would have to create it which would be a fair bit of work for me. I was preventing a printf as an alternative to using sdWriteTimeout.

Also does sdWriteTimeout go to an idle state while it waits to timeout? It was unclear to me if it would remain idle until timeout, or if I could use those CPU cycles for other tasks while it waits.

Posted: **Thu Feb 04, 2021 1:45 am**

Hi,
For listening to SDU events you need to create an event listener which masks in the CHN_CONNECTED and CHN_DISCONNECTED events from SDU and posts an event (of your definition) for the output thread.
The output thread will get the event, analyse the event flags from the SDU channel and enable/disable writing to the channel accordingly.

Below is a simplified general way of doing this (incomplete code).
--
Bob

Code: Select all

  #define CONSOLE_CHANNEL_EVT         EVENT_MASK(0)
  /* Event listener objects. */
    event_listener_t con_el;
    
  /* Clear any prior event and attach event listener to serial channel. */
  (void)chEvtGetAndClearEvents(CONSOLE_CHANNEL_EVT);
  chEvtRegisterMaskWithFlags(
                      chnGetEventSource((BaseAsynchronousChannel *)chp),
                      &con_el, CONSOLE_CHANNEL_EVT,
                      CHN_CONNECTED | CHN_DISCONNECTED);

  /* Flush any channel events prior to running channel. */
  (void)chEvtGetAndClearFlags(&con_el);
  
    do {
       eventmask_t evt = chEvtWaitAnyTimeout(CONSOLE_CHANNEL_EVT, TIME_IMMEDIATE);
        eventflags_t evtf = chEvtGetAndClearFlags(&con_el);
       if (evt != 0) {
          /* Set flag or clear flag to control writing to channel depending on evtf values. */
          if (evtf & CHN_CONNECTED != 0) {
             /* Set flag to enable writing to channel. */
          }
          else {
             /* Set flag to disable writing to channel. */
          }
       }
       else {
          /* Do regular processing. Write to channel only if enabled . */
       }
    } while (true);

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