main.cpp

00001 #include "mbed.h"
00002 
00003 Ticker ticker;
00004 Thread thread;
00005 Queue<const char*, 5> trail;
00006 
00007 // Since we're printing from multiple threads, we need a mutex
00008 Mutex print_lock;
00009 
00010 enum ExecutionTypes {
00011     IDLE,
00012     USER,
00013     ISR
00014 };
00015 
00016 const char* ExecutionMessages[] = {
00017     "the idle thread",
00018     "a user thread",
00019     "interrupt context"
00020 };
00021 
00022 void handler() {
00023     // Check to see if we're in interrupt context
00024     if (core_util_is_isr_active()) {
00025         // Do not print since we're in interrupt context
00026         trail.put(&(ExecutionMessages[ISR]));
00027     } else {
00028         // Safe to print since we're in a user thread
00029         print_lock.lock();
00030         printf("Starting user thread\r\n");
00031         print_lock.unlock();
00032         while(true) {
00033             trail.put(&(ExecutionMessages[USER]));
00034             wait(5);
00035         }
00036     }
00037 }
00038 
00039 void custom_idle_function() {
00040     // Custom idle behavior would go here
00041     // We won't print here since the default idle thread's stack is too small
00042     trail.put(&(ExecutionMessages[IDLE]));
00043 
00044     // Switch back to the default idle behavior
00045     Kernel::attach_idle_hook(NULL);
00046 }
00047 
00048 int main() {
00049     printf("Starting execution example\r\n");
00050 
00051     // Attach the custom idle thread function
00052     Kernel::attach_idle_hook(custom_idle_function);
00053 
00054     // Trigger the interrupt every 3 seconds
00055     ticker.attach(handler, 3);
00056 
00057     // Start the user thread
00058     thread.start(handler);
00059 
00060     // Get the past exectuion trail
00061     while (true) {
00062         osEvent evt = trail.get();
00063         if (evt.status != osEventMessage) {
00064             print_lock.lock();
00065             printf("Failed to retrieve the execution trail (returned %02x)\r\n", evt.status);
00066             print_lock.unlock();
00067         } else {
00068             print_lock.lock();
00069             printf("Execution was in %s\r\n", *(const char**)evt.value.v);
00070             print_lock.unlock();
00071         }
00072     }
00073 }