Diff: main.cpp

Revision:

0:2a0e4f8a7b76

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Feb 23 13:32:14 2016 +0000
@@ -0,0 +1,88 @@
+/** 10_rtos_mempool
+ *
+ * Simple example to use a Mempool object together with a Queue
+ * object in order to send more complex messages from thread1 to thread2.
+ * Thread1 generates transition between random RGB colors and sends
+ * messages to Thread2. Thread2 displays the requested color on the
+ * built in RGB LED.
+ *
+ * Data items for messages are stored in a MemoryPool object.
+ * Thread1 allocates MemoryPool slots, Thread2 should free up
+ * these slots after using up data stored in the slot.
+ */
+
+#include "mbed.h"
+#include "rtos.h"
+PwmOut rled(LED_RED);
+PwmOut gled(LED_GREEN);
+PwmOut bled(LED_BLUE);
+
+typedef struct {
+    float red;
+    float green;
+    float blue;
+} message_t;
+
+MemoryPool<message_t, 4> mpool;                     //Memory pool for data storage
+Queue<message_t, 4> queue;                          //Message queue for 4 items
+
+void led_thread(void const *argument)
+{
+    rled.period_ms(20);                             //Set period to 20 ms
+    rled.write(1.0f);                               //Initialize to 0% duty cycle
+    gled.period_ms(20);                             //Set period to 20 ms
+    gled.write(1.0f);                               //Initialize to 0% duty cycle
+    bled.period_ms(20);                             //Set period to 20 ms
+    bled.write(1.0f);                               //Initialize to 0% duty cycle
+    while (true) {
+        osEvent evt = queue.get();                  //Wait for a message
+        if(evt.status == osEventMessage) {
+            message_t *mymessage = (message_t*)evt.value.p;
+            rled = 1.0f - mymessage->red;
+            gled = 1.0f - mymessage->green;
+            bled = 1.0f - mymessage->blue;
+            mpool.free(mymessage);                  //Free up memory
+        }
+    }
+}
+
+float frand(void)
+{
+    float rv = (float)(rand()&0xFFFF);
+    return (rv/65536.0f);
+}
+
+int main (void)
+{
+    float RGB1[3];
+    float RGB2[3];
+    float INC[3];
+    Thread thread2(led_thread);
+//--- Create a random color ---------------------
+    for (int x=0; x<3; x++) {
+        RGB1[x] = frand();
+    }
+
+    while (true) {
+//--- Create a new random color -----------------
+        for (int x=0; x<3; x++) {
+            RGB2[x] = frand();
+        }
+//--- Determine increments to go from color 1 to color 2 in 25 steps
+        for (int x=0; x<3; x++) {
+            INC[x] = (RGB1[x] - RGB2[x]) / 25;
+        }       
+//--- Send color codes to thread2 ---------------
+        for (int s=0; s<25; s++) {
+            message_t *message = mpool.alloc();     //Allocate memory
+            message->red = RGB1[0];
+            message->green = RGB1[1];
+            message->blue = RGB1[2];
+            queue.put(message);                     //Send data as message
+            Thread::wait(100);
+            for (int x=0; x<3; x++) {
+                RGB1[x] -= INC[x];                  //Approach to second colour
+            }
+        }
+    }
+}