systick testing and simplification

ripped out marti's SystemTick for the sake of simplicity and added a
systick_resume function to libmaple. new example program demonstrates
the functionality, also demonstrates micros()/USB bug

1 files changed, 60 insertions, 0 deletions

diff --git a/examples/test-systick.cpp b/examples/test-systick.cpp
new file mode 100644
index 0000000..247892d
--- /dev/null
+++ b/examples/test-systick.cpp
@@ -0,0 +1,60 @@
+// Tests the SysTick enable/disable functions
+//
+#include "wirish.h"
+#include "systick.h"
+
+#define LED_PIN 13
+#define PWM_PIN  2
+#define BUT     38
+
+void setup()
+{
+    /* Set up the LED to blink  */
+    pinMode(LED_PIN, OUTPUT);
+
+    /* Turn on PWM on pin PWM_PIN */
+    pinMode(PWM_PIN, PWM);
+    pwmWrite(PWM_PIN, 0x8000);
+
+    pinMode(BUT, INPUT_PULLDOWN);
+}
+
+int toggle = 0;
+long time = 0;
+
+void loop() {
+    toggle ^= 1;
+    digitalWrite(LED_PIN, toggle);
+
+    // An artificial delay
+    int16 i = 1;
+    float j = 1;
+    for(i=0; i<6553; i++) {
+        j = sqrt(j) + 1; 
+    }
+        
+    if(digitalRead(BUT)) {
+        systick_disable();
+    } else {
+        systick_resume();
+    }
+
+    //SerialUSB.println(micros());      // there is a bug with this
+    SerialUSB.println(millis());
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated object that need libmaple may fail.
+ __attribute__(( constructor )) void premain() {
+    init();
+}
+
+int main(void)
+{
+    setup();
+
+    while (1) {
+        loop();
+    }
+    return 0;
+}