From dfb98490f42c4aec7a69592e682705cfefaf930a Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Mon, 13 May 2013 15:13:19 +1000
Subject: [PATCH] AP_Airspeed: use rationmetric analog input for airspeed
sensor
---
libraries/AP_Airspeed/AP_Airspeed.cpp | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/libraries/AP_Airspeed/AP_Airspeed.cpp b/libraries/AP_Airspeed/AP_Airspeed.cpp
index cd2d54763..0d1d17063 100644
--- a/libraries/AP_Airspeed/AP_Airspeed.cpp
+++ b/libraries/AP_Airspeed/AP_Airspeed.cpp
@@ -47,10 +47,10 @@ const AP_Param::GroupInfo AP_Airspeed::var_info[] PROGMEM = {
/*
this scaling factor converts from the old system where we used a
- 0 to 1023 raw ADC value for 0-5V to the new system which gets the
+ 0 to 4095 raw ADC value for 0-5V to the new system which gets the
voltage in volts directly from the ADC driver
*/
-#define SCALING_OLD_CALIBRATION 204.8f // 1024/5
+#define SCALING_OLD_CALIBRATION 819 // 4095/5
// calibrate the airspeed. This must be called at least once before
// the get_airspeed() interface can be used
@@ -61,10 +61,10 @@ void AP_Airspeed::calibrate()
if (!_enable) {
return;
}
- _source->voltage_average();
+ _source->voltage_average_ratiometric();
for (c = 0; c < 10; c++) {
hal.scheduler->delay(100);
- sum += _source->voltage_average() * SCALING_OLD_CALIBRATION;
+ sum += _source->voltage_average_ratiometric() * SCALING_OLD_CALIBRATION;
}
float raw = sum/c;
_offset.set_and_save(raw);
@@ -78,7 +78,7 @@ void AP_Airspeed::read(void)
if (!_enable) {
return;
}
- float raw = _source->voltage_average() * SCALING_OLD_CALIBRATION;
+ float raw = _source->voltage_average_ratiometric() * SCALING_OLD_CALIBRATION;
airspeed_pressure = max(raw - _offset, 0);
float new_airspeed = sqrtf(airspeed_pressure * _ratio);
_airspeed = 0.7f * _airspeed + 0.3f * new_airspeed;
--
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