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AP_InertialSensor: improved handling of I2C invensense sensor 

on I2C the lower bus bandwidth changes the tradeoffs
This commit is contained in:
Andrew Tridgell 2018-01-31 19:11:12 +11:00
parent b33c815e96
commit b380143349
1 changed files with 16 additions and 5 deletions
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15
libraries/AP_InertialSensor/AP_InertialSensor_Invensense.cpp
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@ -519,11 +519,21 @@ void AP_InertialSensor_Invensense::_read_fifo()
the ones at the end of the FIFO, so clear those with a reset
once we've read the first 24. Reading 24 gives us the normal
number of samples for fast sampling at 400Hz
On I2C with the much lower clock rates we need a lower threshold
or we may never catch up
*/
if (_dev->bus_type() == AP_HAL::Device::BUS_TYPE_I2C) {
if (n_samples > 4) {
need_reset = true;
n_samples = 4;
}
} else {
if (n_samples > 32) {
need_reset = true;
n_samples = 24;
}
}
while (n_samples > 0) {
uint8_t n = MIN(n_samples, MPU_FIFO_BUFFER_LEN);
@ -716,8 +726,9 @@ bool AP_InertialSensor_Invensense::_hardware_init(void)
return false;
}
// setup for register checking
_dev->setup_checked_registers(7, 20);
// setup for register checking. We check much less often on I2C
// where the cost of the checks is higher
_dev->setup_checked_registers(7, _dev->bus_type() == AP_HAL::Device::BUS_TYPE_I2C?200:20);
// initially run the bus at low speed
_dev->set_speed(AP_HAL::Device::SPEED_LOW);