ao-bringup-avr: Switch to ADC13

That's what Bdale has wired up in his test setup.

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 60922826187dedd0102822ea2861a7a2abe1de30..12b1abfc00a6e49f899655091d6b16a18f538e27 100644 (file)
--- a/ao-bringup-avr/ao-blink.c
+++ b/ao-bringup-avr/ao-blink.c
@@ -125,33 +125,37 @@ ISR(ADC_vect)
        OCR0A = ADCH;
 }
 
+#define ADC_CHANNEL    0x25            /* Channel ADC13 */
+#define ADC_CHANNEL_LOW(c)     (((c) & 0x1f) << MUX0)
+#define ADC_CHANNEL_HIGH(c)    ((((c) & 0x20) >> 5) << MUX5)
+
+#define ADCSRA_INIT    ((1 << ADEN) |          /* Enable ADC */                \
+                        (0 << ADATE) |         /* No auto ADC trigger */       \
+                        (1 << ADIE) |          /* Enable interrupt */  \
+                        (6 << ADPS0))          /* Prescale clock by 64 */
+
+#define ADCSRB_INIT    ((0 << ADHSM) |         /* No high-speed mode */ \
+                        (0 << ACME) |          /* Some comparitor thing */ \
+                        (0 << ADTS0))          /* Free running mode (don't care) */
+
 static void
 adc_start(void)
 {
-       ADMUX = ((0 << REFS1) |
-                (1 << REFS0) |
-                (1 << ADLAR) |
-                (0 << MUX0));
-       ADCSRB &= ~(1 << MUX5);
-
-       ADCSRA = ((1 << ADEN) |
-                 (1 << ADSC) |
-                 (0 << ADATE) |
-                 (1 << ADIE) |
-                 (6 << ADPS0));
+       ADMUX = ((0 << REFS1) |                         /* AVcc reference */
+                (1 << REFS0) |                         /* AVcc reference */
+                (1 << ADLAR) |                         /* Left-shift results */
+                (ADC_CHANNEL_LOW(ADC_CHANNEL)));       /* Select channel */
+
+       ADCSRB = ADCSRB_INIT | ADC_CHANNEL_HIGH(ADC_CHANNEL);
+
+       ADCSRA = ADCSRA_INIT | (1 << ADSC);             /* Start conversion */
 }
 
 static void
 adc_init(void)
 {
-       ADCSRA = ((1 << ADEN) |
-                 (0 << ADSC) |
-                 (0 << ADATE) |
-                 (1 << ADIE) |
-                 (6 << ADPS0));
-       ADCSRB = ((0 << ADHSM) |
-                 (0 << MUX5) |
-                 (0 << ADTS0));
+       ADCSRA = ADCSRA_INIT;
+       ADCSRB = ADCSRB_INIT;
        DIDR0 |= (1 << 0);
 }