ao-bringup-avr: Initialize crystal clock and 100Hz timer interrupt

Just demonstrating further features of the chip

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/ao-bringup-avr/ao-blink.c b/ao-bringup-avr/ao-blink.c
index 4d726fd9c60be63eb5772234b0990229d254abee..fa95831529bb84a4ce5dd31ddfb8ba89c40951f2 100644 (file)
--- a/ao-bringup-avr/ao-blink.c
+++ b/ao-bringup-avr/ao-blink.c
@@ -25,7 +25,35 @@
 #define LEDDDR         DDRB
 #define LEDDDRPIN      DD7
 
-int main(void)
+ISR(TIMER1_COMPA_vect)
+{
+       static int      x;
+
+       if (++x > 50) {
+               x = 0;
+               LEDPORT ^= (1 << LEDOUT);
+       }
+}
+
+static void
+timer_init(void)
+{
+       TCCR1A = ((0 << WGM11) |        /* CTC mode, OCR1A */
+                 (0 << WGM10));        /* CTC mode, OCR1A */
+       TCCR1B = ((0 << ICNC1) |        /* no input capture noise canceler */
+                 (0 << ICES1) |        /* input capture on falling edge (don't care) */
+                 (0 << WGM13) |        /* CTC mode, OCR1A */
+                 (1 << WGM12) |        /* CTC mode, OCR1A */
+                 (3 << CS10));         /* clk/64 from prescaler */
+
+       OCR1A = 2500;                   /* 16MHz clock */
+       // OCR1A = 1250;                /* 8MHz clock */
+
+       TIMSK1 = (1 << OCIE1A);         /* Interrupt on compare match */
+}
+
+static void
+clock_init(void)
 {
        /* disable RC clock */
        CLKSEL0 &= ~(1 << RCE);
@@ -65,13 +93,23 @@ int main(void)
        PLLCSR |= (1 << PLLE);
        while (!(PLLCSR & (1 << PLOCK)))
                ;
+}
+
+int main(void)
+{
+       clock_init();
+       timer_init();
 
        LEDDDR |= (1 << LEDDDRPIN);
 
+       for (;;) {
+       }
+#if 0
        while (1) {
                LEDPORT |= (1 << LEDOUT);
                _delay_ms(1000);
                LEDPORT &= ~(1 << LEDOUT);
                _delay_ms(1000);
        }
+#endif
 }