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APM: switch to Randys new IMU rate control method 

this drives the speed of the 50Hz loop by the number of samples
accumulated in the IMU. This should give much more consistent timing
in DCM.

Thanks to Randy for introducing this scheme in ArduCopter!
This commit is contained in:
Andrew Tridgell 2012-09-11 16:39:36 +10:00
parent 834f961409
commit 5f3ffe4839
2 changed files with 16 additions and 4 deletions
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8
ArduPlane/ArduPlane.pde
View File

@ -709,9 +709,9 @@ void setup() {
void loop()
{
// We want this to execute at 50Hz if possible
// -------------------------------------------
if (millis() - fast_loopTimer_ms > 19) {
// We want this to execute at 50Hz, but synchronised with the gyro/accel
uint16_t num_samples = imu.num_samples_available();
if (num_samples >= NUM_IMU_SAMPLES_FOR_50HZ) {
delta_ms_fast_loop = millis() - fast_loopTimer_ms;
load = (float)(fast_loopTimeStamp_ms - fast_loopTimer_ms)/delta_ms_fast_loop;
G_Dt = (float)delta_ms_fast_loop / 1000.f;
@ -745,7 +745,7 @@ void loop()
}
fast_loopTimeStamp_ms = millis();
} else {
} else if (num_samples < NUM_IMU_SAMPLES_FOR_50HZ-1) {
// less than 20ms has passed. We have at least one millisecond
// of free time. The most useful thing to do with that time is
// to accumulate some sensor readings, specifically the

12
ArduPlane/config.h
View File

@ -853,3 +853,15 @@
#ifndef SERIAL_BUFSIZE
# define SERIAL_BUFSIZE 256
#endif
#if CONFIG_IMU_TYPE == CONFIG_IMU_OILPAN
# define NUM_IMU_SAMPLES_FOR_200HZ 5
# define NUM_IMU_SAMPLES_FOR_100HZ 10
# define NUM_IMU_SAMPLES_FOR_50HZ 20
#endif
#if CONFIG_IMU_TYPE == CONFIG_IMU_MPU6000
# define NUM_IMU_SAMPLES_FOR_200HZ 1
# define NUM_IMU_SAMPLES_FOR_100HZ 2
# define NUM_IMU_SAMPLES_FOR_50HZ 4
#endif