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[ardrone] baro-temp-press-swap-due-to-non-understood-sensorboard-interrupt-delay-bug solved with specialized spike filter

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This commit is contained in:
Christophe De Wagter
2013-12-16 16:27:19 +01:00
parent f8d1a352cf
commit 792e043345
1 changed files with 41 additions and 2 deletions
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sw/airborne/boards/ardrone/navdata.c
+40 -1
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@@ -269,7 +269,9 @@ static void baro_update_logic(void)
static uint16_t lasttempval = 0;
static uint8_t temp_or_press_was_updated_last = 0; // 0 = press, so we now wait for temp, 1 = temp so we now wait for press
static int sync_errors;
static int sync_errors = 0;
static int spikes = 0;
static int spike_detected = 0;
if (temp_or_press_was_updated_last == 0) // Last update was press so we are now waiting for temp
{
@@ -309,8 +311,43 @@ static void baro_update_logic(void)
}
}
if (spike_detected == 0)
{
navdata_baro_available = TRUE;
}
}
/*
* It turns out that a lot of navdata boards have a problem (probably interrupt related)
* in which reading I2C data and writing uart output data is interrupted very long (50% of 200Hz).
* Afterwards, the 200Hz loop tries to catch up lost time but reads the baro too fast swapping the
* pressure and temperature values by exceeding the minimal conversion time of the bosh baro. The
* normal Parrot firmware seems to be perfectly capable to fly with this, either with excessive use of
* the sonar or with software filtering or spike detection. Paparazzi with its tightly coupled baro-altitude
* had problems. Since this problems looks not uncommon a detector was made. A lot of evidence is grabbed
* with a logic analyzer on the navboard I2C and serial output. The UART CRC is still perfect, the baro
* temp-press-temp-press logic is still perfect, so not easy to detect. Temp and pressure are swapped,
* and since both can have almost the same value, the size of the spike is not predictable. However at
* every spike of at least 3 broken boards the press and temp are byte-wise exactly the same due to
* reading them too quickly (trying to catch up for delay that happened earlier due to still non understood
* reasons. As pressure is more likely to quickly change, a small (yet unlikely) spike on temperature together with
* press==temp yields very good results as a detector, although theoretically not perfect.
*/
// if press and temp are same and temp has jump: neglect the next frame
if ((navdata.temperature_pressure == navdata.pressure) && (abs(navdata.temperature_pressure - lasttempval) > 40))
{
// dont use next 3 packets
spike_detected = 3;
// dont use
navdata_baro_available = FALSE;
spikes++;
printf("Spike! # %d\n",spikes);
}
if (spike_detected)
spike_detected--;
lastpressval = navdata.pressure;
lasttempval = navdata.temperature_pressure;
@@ -370,6 +407,8 @@ void navdata_update()
p[0] = p[1];
p[1] = tmp;
// printf("%d %d %d\n",navdata.nu_trame, navdata.pressure, navdata.temperature_pressure);
baro_update_logic();
#ifdef USE_SONAR