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authorDimitri Sokolyuk <demon@dim13.org>2011-03-12 00:45:23 +0000
committerDimitri Sokolyuk <demon@dim13.org>2011-03-12 00:45:23 +0000
commit1026e533722f68fbcaa0167c4c172540afcabeba (patch)
tree513873e40c065b708699d4661ac21f3739c22823 /kernel/adc.c
parentb8335062ae7d19bd27e6131fadcd7d3a116c4992 (diff)
add ADC task
Diffstat (limited to 'kernel/adc.c')
-rw-r--r--kernel/adc.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/kernel/adc.c b/kernel/adc.c
new file mode 100644
index 0000000..f48fccd
--- /dev/null
+++ b/kernel/adc.c
@@ -0,0 +1,49 @@
+/* $Id$ */
+/*
+ * Copyright (c) 2011 Dimitri Sokolyuk <demon@dim13.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <inttypes.h>
+#include <avr/io.h>
+#include "kernel.h"
+#include "tasks.h"
+
+uint16_t
+rdadc(uint8_t ch)
+{
+ ADMUX &= ~0x07;
+ ADMUX |= (ch & 0x07);
+ ADCSRA |= _BV(ADSC);
+ loop_until_bit_is_set(ADCSRA, ADSC);
+
+ return ADCW;
+}
+
+void
+adc(void *arg)
+{
+ struct adcarg *a = (struct adcarg *)arg;
+ a->r = release();
+ a->d = deadline();
+
+ /* prescale 8 */
+ ADCSRA |= (_BV(ADEN) | _BV(ADFR) | _BV(ADPS1) | _BV(ADPS0));
+
+ for (;;) {
+ *a->value = rdadc(a->channel);
+ a->r = a->d += MSEC(20);
+ update(a->r, a->d);
+ }
+}