/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
/*
driver for TeraRanger I2C rangefinders
*/
#include "AP_RangeFinder_TeraRangerI2C.h"
#include
#include
#include
extern const AP_HAL::HAL& hal;
// registers
#define TR_MEASURE 0x00
#define TR_WHOAMI 0x01
#define TR_WHOAMI_VALUE 0xA1
/*
The constructor also initializes the rangefinder. Note that this
constructor is not called until detect() returns true, so we
already know that we should setup the rangefinder
*/
AP_RangeFinder_TeraRangerI2C::AP_RangeFinder_TeraRangerI2C(RangeFinder::RangeFinder_State &_state,
AP_RangeFinder_Params &_params,
AP_HAL::OwnPtr i2c_dev)
: AP_RangeFinder_Backend(_state, _params)
, dev(std::move(i2c_dev))
{
}
/*
detect if a TeraRanger rangefinder is connected. We'll detect by
trying to take a reading on I2C. If we get a result the sensor is
there.
*/
AP_RangeFinder_Backend *AP_RangeFinder_TeraRangerI2C::detect(RangeFinder::RangeFinder_State &_state,
AP_RangeFinder_Params &_params,
AP_HAL::OwnPtr i2c_dev)
{
if (!i2c_dev) {
return nullptr;
}
AP_RangeFinder_TeraRangerI2C *sensor = new AP_RangeFinder_TeraRangerI2C(_state, _params, std::move(i2c_dev));
if (!sensor) {
return nullptr;
}
if (!sensor->init()) {
delete sensor;
return nullptr;
}
return sensor;
}
/*
initialise sensor
*/
bool AP_RangeFinder_TeraRangerI2C::init(void)
{
if (!dev->get_semaphore()->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
return false;
}
dev->set_retries(10);
// check WHOAMI
uint8_t whoami;
if (!dev->read_registers(TR_WHOAMI, &whoami, 1) ||
whoami != TR_WHOAMI_VALUE) {
dev->get_semaphore()->give();
return false;
}
if (!measure()) {
dev->get_semaphore()->give();
return false;
}
// give time for the sensor to process the request
hal.scheduler->delay(70);
uint16_t _distance_cm;
if (!collect_raw(_distance_cm)) {
dev->get_semaphore()->give();
return false;
}
dev->get_semaphore()->give();
dev->set_retries(1);
dev->register_periodic_callback(10000,
FUNCTOR_BIND_MEMBER(&AP_RangeFinder_TeraRangerI2C::timer, void));
return true;
}
// measure() - ask sensor to make a range reading
bool AP_RangeFinder_TeraRangerI2C::measure()
{
uint8_t cmd = TR_MEASURE;
return dev->transfer(&cmd, 1, nullptr, 0);
}
// collect_raw() - return last value measured by sensor
bool AP_RangeFinder_TeraRangerI2C::collect_raw(uint16_t &raw_distance)
{
uint8_t d[3];
// Take range reading
if (!dev->transfer(nullptr, 0, d, sizeof(d))) {
return false;
}
// Check for CRC
if (d[2] != crc_crc8(d, 2)) {
return false;
} else {
raw_distance = ((uint16_t(d[0]) << 8) | d[1]);
return true;
}
}
// Checks for error code and if correct converts to cm
bool AP_RangeFinder_TeraRangerI2C::process_raw_measure(uint16_t raw_distance, uint16_t &output_distance_cm)
{
// Check for error codes
if (raw_distance == 0xFFFF) {
// Too far away is unreliable so we dont enforce max range here
return false;
} else if (raw_distance == 0x0000) {
// Too close
output_distance_cm = params.min_distance_cm;
return true;
} else if (raw_distance == 0x0001) {
// Unable to measure
return false;
} else {
output_distance_cm = raw_distance/10; // Conversion to centimeters
return true;
}
}
/*
timer called at 100Hz, EVO sensors max freq is 100..240Hz
*/
void AP_RangeFinder_TeraRangerI2C::timer(void)
{
// Take a reading
uint16_t _raw_distance = 0;
uint16_t _distance_cm = 0;
if (collect_raw(_raw_distance)) {
WITH_SEMAPHORE(_sem);
if (process_raw_measure(_raw_distance, _distance_cm)){
accum.sum += _distance_cm;
accum.count++;
}
}
// and immediately ask for a new reading
measure();
}
/*
update the state of the sensor
*/
void AP_RangeFinder_TeraRangerI2C::update(void)
{
WITH_SEMAPHORE(_sem);
if (accum.count > 0) {
state.distance_cm = accum.sum / accum.count;
state.last_reading_ms = AP_HAL::millis();
accum.sum = 0;
accum.count = 0;
update_status();
} else if (AP_HAL::millis() - state.last_reading_ms > 200) {
set_status(RangeFinder::Status::NoData);
}
}