first commit

1 files changed, 65 insertions, 0 deletions

diff --git a/main.c b/main.c
new file mode 100644
index 0000000..cd3cf6e
--- /dev/null
+++ b/main.c
@@ -0,0 +1,65 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include "uart.h"
+
+#define SET_PWM(a) (OCR0A  = (a))
+
+void setup(void);
+
+int main(void)
+{
+    uint8_t output = 0, c;
+
+    setup();
+
+    for (;;) {
+        switch((c = uart_getchar())) {
+            case '?': break;
+            case 'n':
+            case '0': output  = 0; break;
+            case 'y':
+            case '1': output  = 1; break;
+            case 't':
+            case 'T': output ^= 1; break;
+        }
+
+        uart_putchar(c);
+
+        if (output)
+            SET_PWM(40);
+        else
+            SET_PWM(1);
+
+        _delay_ms(1000);
+        SET_PWM(0);
+    }
+
+    return 0;
+}
+
+void setup(void)
+{
+    /* serial */
+    uart_init();
+
+    /* Initialize timer for PWM
+     *** PWM with timer1 management:
+     * TCCR1A-COM1A1:
+     * TCCR1A-WGM10:
+     * TOP = 0x00FF
+     * frequency is : 12 MHz(fclk) / 256(prscl) / 255 (top)/ 2 = 91.91Hz
+     * frequency is : 18.432 MHz(fclk) / 256(prscl) / 255 (top)/ 2 = 141.18Hz
+     * frequency is : 18.432 MHz(fclk) / 1024(prscl) / 255 (top)/ 2 = 35.29Hz
+     * frequency is : 16 MHz(fclk) / 1024(prscl) / 255 (top)/ 2 = 30.64Hz
+     * TCCR1B CS12 = 256 prescaler, CS12 + CS10 = 1024 prescaler
+     *
+     * 23/24 =~ 1.5ms
+     */
+    TCCR0A |= _BV(COM1A1)  | _BV(WGM10);
+    TCCR0B |= _BV(CS12)    | _BV(CS10);
+    /* TIMSK0 |= _BV(TOIE0); */
+
+    /* pwm output; */
+    DDRD |= 0xFF;
+}