AP_InertialSensor: fix comments surrounding fast rate sampling

ArduPilot · Nov 19, 2024 · 37d1e8d · 37d1e8d
1 parent f9e319d
commit 37d1e8d
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Showing 4 changed files with 13 additions and 13 deletions.
diff --git a/libraries/AP_InertialSensor/AP_InertialSensor.cpp b/libraries/AP_InertialSensor/AP_InertialSensor.cpp
@@ -577,10 +577,10 @@ const AP_Param::GroupInfo AP_InertialSensor::var_info[] = {
 #endif
 
     // @Param: _GYRO_RATE
-    // @DisplayName: Gyro rate for IMUs with Fast Sampling enabled
-    // @Description: Gyro rate for IMUs with fast sampling enabled. The gyro rate is the sample rate at which the IMU filters operate and needs to be at least double the maximum filter frequency. If the sensor does not support the selected rate the next highest supported rate will be used. For IMUs which do not support fast sampling this setting is ignored and the default gyro rate of 1Khz is used.
+    // @DisplayName: Gyro rate multiplier for IMUs with Fast Sampling enabled
+    // @Description: Gyro rate multipier for IMUs with fast sampling enabled. The gyro rate is the sample rate multiplier of base output data rate at which the IMU filters operate and needs to be at least double the maximum filter frequency. If the sensor does not support the selected rate the next highest supported rate will be used. For IMUs which do not support fast sampling this setting is ignored and the default gyro rate is used.
     // @User: Advanced
-    // @Values: 0:1kHz,1:2kHz,2:4kHz,3:8kHz
+    // @Values: 0:x1,1:x2,2:x4,3:x8
     // @RebootRequired: True
     AP_GROUPINFO("_GYRO_RATE",  42, AP_InertialSensor, _fast_sampling_rate, MPU_FIFO_FASTSAMPLE_DEFAULT),
 

diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_Backend.h b/libraries/AP_InertialSensor/AP_InertialSensor_Backend.h
@@ -319,7 +319,7 @@ class AP_InertialSensor_Backend
         return (HAL_INS_HIGHRES_SAMPLE & (1U<<instance)) != 0;
     }
 
-    // if fast sampling is enabled, the rate to use in kHz
+    // if fast sampling is enabled, the base rate multiplier to use
     uint8_t get_fast_sampling_rate() const {
         return (1 << uint8_t(_imu._fast_sampling_rate));
     }

diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.cpp b/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.cpp
@@ -669,21 +669,21 @@ void AP_InertialSensor_Invensensev3::register_write_bank(uint8_t bank, uint8_t r
 }
 
 // calculate the fast sampling backend rate
-uint16_t AP_InertialSensor_Invensensev3::calculate_fast_sampling_backend_rate(uint16_t base_odr, uint16_t max_odr) const
+uint16_t AP_InertialSensor_Invensensev3::calculate_fast_sampling_backend_rate(uint16_t base_backend_rate, uint16_t max_backend_rate) const
 {
     // constrain the gyro rate to be at least the loop rate
-    uint8_t loop_limit = 1;
-    if (get_loop_rate_hz() > base_odr) {
-        loop_limit = 2;
+    uint8_t min_base_rate_multiplier = 1;
+    if (get_loop_rate_hz() > base_backend_rate) {
+        min_base_rate_multiplier = 2;
     }
-    if (get_loop_rate_hz() > base_odr * 2) {
-        loop_limit = 4;
+    if (get_loop_rate_hz() > base_backend_rate * 2) {
+        min_base_rate_multiplier = 4;
     }
     // constrain the gyro rate to be a 2^N multiple
-    uint8_t fast_sampling_rate = constrain_int16(get_fast_sampling_rate(), loop_limit, 8);
+    uint8_t fast_sampling_rate_multiplier = constrain_int16(get_fast_sampling_rate(), min_base_rate_multiplier, 8);
 
     // calculate rate we will be giving samples to the backend
-    return constrain_int16(base_odr * fast_sampling_rate, base_odr, max_odr);
+    return constrain_int16(base_backend_rate * fast_sampling_rate_multiplier, base_backend_rate, max_backend_rate);
 }
 
 /*

diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.h b/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.h
@@ -58,7 +58,7 @@ class AP_InertialSensor_Invensensev3 : public AP_InertialSensor_Backend
     void set_filter_and_scaling_icm42670(void);
     void set_filter_and_scaling_icm456xy(void);
     void fifo_reset();
-    uint16_t calculate_fast_sampling_backend_rate(uint16_t base_odr, uint16_t max_odr) const;
+    uint16_t calculate_fast_sampling_backend_rate(uint16_t base_backend_rate, uint16_t max_backend_rate) const;
 
     /* Read samples from FIFO */
     void read_fifo();