From: Keith Packard <keithp@keithp.com>
Date: Wed, 20 Dec 2017 00:56:33 +0000 (-0800)
Subject: altos/attiny: Add ADC implementation
X-Git-Tag: 1.8.4~1^2~3
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=99299986e194337b05ee81cfb7c4aa1cb9e9a74e;ds=sidebyside

altos/attiny: Add ADC implementation

It's primitive, but might serve to read ADC values. Untested.

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

diff --git a/src/attiny/ao_adc_attiny.c b/src/attiny/ao_adc_attiny.c
new file mode 100644
index 00000000..3a835d13
--- /dev/null
+++ b/src/attiny/ao_adc_attiny.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright © 2017 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <ao.h>
+
+/*
+ * ATtiny ADC interface
+ */
+
+uint16_t
+ao_adc_read(uint8_t mux)
+{
+	uint8_t	low, high;
+
+	/* Set the mux */
+	ADMUX = mux;
+
+	/* Start conversion */
+	ADCSRA = ((1 << ADEN) |
+		  (1 << ADSC) |
+		  (0 << ADATE) |
+		  (0 << ADIF) |
+		  (0 << ADIE) |
+		  (0 << ADPS2) |
+		  (0 << ADPS1) |
+		  (0 << ADPS0));
+
+	/* Await conversion complete */
+	while ((ADCSRA & (1 << ADSC)) != 0)
+		;
+
+	/* Read low first */
+	low = ADCL;
+	high = ADCH;
+
+	return (((uint16_t) high) << 8) | low;
+}
diff --git a/src/attiny/ao_arch.h b/src/attiny/ao_arch.h
index 3a34f417..68f5702d 100644
--- a/src/attiny/ao_arch.h
+++ b/src/attiny/ao_arch.h
@@ -85,4 +85,7 @@ ao_eeprom_read(uint16_t addr, void *buf, uint16_t len);
 void
 ao_eeprom_write(uint16_t addr, void *buf, uint16_t len);
 
+uint16_t
+ao_adc_read(uint8_t mux);
+
 #endif /* _AO_ARCH_H_ */