2 files changed, 44 insertions, 0 deletions
diff --git a/src/core/ao.h b/src/core/ao.h
index 0b634a79..29ad2603 100644
--- a/src/core/ao.h
+++ b/src/core/ao.h
@@ -307,6 +307,17 @@ ao_altitude_to_pa(alt_t alt);
 #include <ao_serial.h>
 #endif
 
+/*
+ * ao_convert_volt.c
+ *
+ * Convert ADC readings to decivolts
+ */
+
+int16_t
+ao_battery_decivolt(int16_t adc);
+
+int16_t
+ao_ignite_decivolt(int16_t adc);
 
 /*
  * ao_spi_slave.c
diff --git a/src/core/ao_convert_volt.c b/src/core/ao_convert_volt.c
new file mode 100644
index 00000000..8556d423
--- /dev/null
+++ b/src/core/ao_convert_volt.c
@@ -0,0 +1,33 @@
+/*
+ * Copyright © 2014 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; version 2 of the License.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "ao.h"
+
+#define scale(v,p,m)	((int32_t) (v) * (AO_ADC_REFERENCE_DV * ((p) + (m))) / (AO_ADC_MAX * (m)))
+
+int16_t
+ao_battery_decivolt(int16_t adc)
+{
+	return scale(adc, AO_BATTERY_DIV_PLUS, AO_BATTERY_DIV_MINUS);
+}
+
+int16_t
+ao_ignite_decivolt(int16_t adc)
+{
+	return scale(adc, AO_IGNITE_DIV_PLUS, AO_IGNITE_DIV_MINUS);
+}
+