HSE usage

[cortex-from-scratch] / systick.c

diff --git a/systick.c b/systick.c
index 1d632ec..05f515f 100644 (file)
--- a/systick.c
+++ b/systick.c
@@ -5,7 +5,8 @@
 #include <sys/robsys.h>
 #include <sys/mmap.h>
 
-#include <lib/regfunc.h> // TODO
+#include <lib/regfunc.h>
+#include <lib/stdio.h>
 
 struct interrupt_frame {
 
@@ -22,25 +23,31 @@ struct interrupt_frame {
 //__attribute__ ((interrupt))
 void * systick_handler(/* struct interrupt_frame * frame */) {
 
-//     uint32_t volatile status;
-       //uart_puts("TICKING\n");
+//     cputs("TICKING\n");
 //     for(;;);
 }
 
 
 void systick_init() {
 
-       /* Enable the counter and enable the interrupt
-        * associated with it */
-       *STK_CTRL = (volatile uint32_t) 0x00000003;
-
-       /* The counter reload register here holds 
-        * 0x1000 -- that's 4096 clock cycles -- if 
-        * it is down to zero it is restores the value */
-       *STK_RELOAD = (volatile uint32_t) 0x00400000; 
-
        /* Every time the counter counts down to zero
         * a systick exception is asserted. Systick has
         * exception number 15. in the vector table  */
        ivt_set_gate(15, systick_handler, 0); 
+
+       /* Get calibration and set this to 1 sec
+        * !Most boards have a 1 ms or 10 ms 
+        * calibration value */
+       int calib = (*STK_CALIB << 0) * 500;
+
+       /* The counter reload registers counts down to zero
+        * and then it is restores the value */
+       rwrite(STK_RELOAD, calib);
+       
+       /* Enable the counter and enable the interrupt
+        * associated with it */
+       rsetbit(STK_CTRL, 0);
+       rsetbit(STK_CTRL, 1);
+
+
 }