Tom Soulanille / RTOS-Serial

An RTOS-friendly Serial interface Its primary benefit is that it never hogs the CPU. An amusing alternative to the traditional ring-bufferd interrupt-serviced systems, it uses short mbed-rtos queues to buffer characters to and from the UART, and a thread to service the transmitter. Short interrupt service routines enqueue received characters and signal the transmit thread when the transmitter is available. WARNING: Do not create RTOS-Serial objects before the RTOS is running! Put them inside your main() block or another function, not in the global initialization.

Dependents:   Test_RDM880_rfid_reader

Diff: rtos_serial.cpp

Revision:
13:2fb32235253c
Parent:
12:be7883573c91
Child:
14:33d60e4eb215
--- a/rtos_serial.cpp	Thu Oct 24 17:30:52 2013 +0000
+++ b/rtos_serial.cpp	Thu Oct 24 18:25:14 2013 +0000
@@ -28,18 +28,22 @@
  */
 #include "rtos_serial.h"
 
-#define START_THREAD 0x80
+#define RTOS_SERIAL_START_THREAD 0x80
+#define RTOS_SERIAL_USE_LED_INDICATOR   0
 
 RTOS_Serial::RTOS_Serial(PinName tx, PinName rx, const char *name)
- : RawSerial(tx, rx), name(name),
+ : RawSerial(tx, rx),
+   name(name),
    _tx_thread(&RTOS_Serial::threadStarter, (void *) this,
                     osPriorityNormal, RTOS_SERIAL_TX_THREAD_STACK_SIZE)
 {
     uart_number = get_index();
-    const PinName leds[] = {LED1,LED2,LED3,LED4};
+#if RTOS_SERIAL_USE_LED_INDICATOR
+    static const PinName leds[] = {LED1,LED2,LED3,LED4};
     ledp = new DigitalOut(leds[uart_number]);
     for (int i=0; i<1; i++) { *ledp=1; wait(0.1); *ledp=0; wait(0.1); }; wait(0.5);
-    _tx_thread.signal_set(START_THREAD);
+#endif
+    _tx_thread.signal_set(RTOS_SERIAL_START_THREAD);
 }
 
 #if 0
@@ -120,23 +124,28 @@
 
 void RTOS_Serial::threadStarter(void const *p) {
     RTOS_Serial *instance = (RTOS_Serial*)p;
-    instance->_tx_thread.signal_set(0x01);   // "prime the pump" of the tx-ready signals
-    instance->tx_emitter(instance);
+    instance->tx_emitter();
 }
 
-void RTOS_Serial::tx_emitter(void const *argument){
-    RTOS_Serial *sp = (RTOS_Serial *) argument;
+void RTOS_Serial::tx_emitter(){
     osEvent evt;
     //osStatus status;
-    _tx_thread.signal_wait(START_THREAD);
+    _tx_thread.signal_wait(RTOS_SERIAL_START_THREAD);
+#if RTOS_SERIAL_USE_LED_INDICATOR
     for (int i=0; i<2; i++) { *ledp=1; wait(0.1); *ledp=0; wait(0.1); }; wait(0.5);
+#endif
     attach(this, &RTOS_Serial::rx_isr, RxIrq);
+#if RTOS_SERIAL_USE_LED_INDICATOR
     for (int i=0; i<3; i++) { *ledp=1; wait(0.1); *ledp=0; wait(0.1); }; wait(0.5);
+#endif
     attach(this, &RTOS_Serial::tx_isr, TxIrq);    
+#if RTOS_SERIAL_USE_LED_INDICATOR
     for (int i=0; i<4; i++) { *ledp=1; wait(0.1); *ledp=0; wait(0.1); }; wait(0.5);
-
+#endif
+    _tx_thread.signal_set(0x01);   // "prime the pump" of the tx-ready signals
+    
     while(true){
-        evt = sp->tx_q.get();
+        evt = tx_q.get();
         if (evt.status == osEventMessage) {
             // There is no TX interrupt until the first byte is sent out the port,
             // so we use a timeout on the signal from the interrupt service routine
@@ -147,12 +156,18 @@
             // is created, so normally this will not come into effect.
             // DEBUG: timeout omitted to search for instabilities
             Thread::signal_wait(0x1/*, 10*/);   //FIXME: base the timeout on the baud rate
-            *(sp->ledp) = 1;
-            sp->parent_putc(evt.value.v);
-            *(sp->ledp) = 0;
+#if RTOS_SERIAL_USE_LED_INDICATOR
+            *ledp = 1;
+#endif
+            parent_putc(evt.value.v);
+#if RTOS_SERIAL_USE_LED_INDICATOR
+            *ledp = 0;
+#endif
         } else {
             std::printf("\r\nRTOS_Serial::tx_emitter() evt.status %d\n", evt.status);
         }
-        *(sp->ledp) = 0;
+#if RTOS_SERIAL_USE_LED_INDICATOR
+        *ledp = 0;
+#endif
     }
 }