ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_LeddarOne.cpp

222 lines
6.2 KiB
C++

/*
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 <http://www.gnu.org/licenses/>.
*/
#include <AP_HAL/AP_HAL.h>
#include "AP_RangeFinder_LeddarOne.h"
#include <AP_SerialManager/AP_SerialManager.h>
extern const AP_HAL::HAL& hal;
/*
The constructor also initialises 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_LeddarOne::AP_RangeFinder_LeddarOne(RangeFinder &_ranger, uint8_t instance,
RangeFinder::RangeFinder_State &_state,
AP_SerialManager &serial_manager) :
AP_RangeFinder_Backend(_ranger, instance, _state)
{
uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar, 0);
if (uart != nullptr) {
uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Lidar, 0));
}
}
/*
detect if a LeddarOne rangefinder is connected. We'll detect by
trying to take a reading on Serial. If we get a result the sensor is
there.
*/
bool AP_RangeFinder_LeddarOne::detect(RangeFinder &_ranger, uint8_t instance, AP_SerialManager &serial_manager)
{
return serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar, 0) != nullptr;
}
// read - return last value measured by sensor
bool AP_RangeFinder_LeddarOne::get_reading(uint16_t &reading_cm)
{
if (uart == nullptr) {
return false;
}
// send a request message for Modbus function 4
if (send_request() != LEDDARONE_OK) {
// TODO: handle LEDDARONE_ERR_SERIAL_PORT
return false;
}
uint32_t start_ms = AP_HAL::millis();
while (!uart->available()) {
// wait up to 200ms
if (AP_HAL::millis() - start_ms > 200) {
return false;
}
}
// parse a response message, set number_detections, detections and sum_distance
// must be signed to handle errors
uint8_t number_detections;
if (parse_response(number_detections) != LEDDARONE_OK) {
// TODO: when (not LEDDARONE_OK) handle LEDDARONE_ERR_
return false;
}
// calculate average distance
reading_cm = sum_distance / number_detections;
return true;
}
/*
update the state of the sensor
*/
void AP_RangeFinder_LeddarOne::update(void)
{
if (get_reading(state.distance_cm)) {
// update range_valid state based on distance measured
last_reading_ms = AP_HAL::millis();
update_status();
} else if (AP_HAL::millis() - last_reading_ms > 200) {
set_status(RangeFinder::RangeFinder_NoData);
}
}
/*
CRC16
CRC-16-IBM(x16+x15+x2+1)
*/
bool AP_RangeFinder_LeddarOne::CRC16(uint8_t *aBuffer, uint8_t aLength, bool aCheck)
{
uint16_t crc = 0xFFFF;
for (uint32_t i=0; i<aLength; i++) {
crc ^= aBuffer[i];
for (uint32_t j=0; j<8; j++) {
if (crc & 1) {
crc = (crc >> 1) ^ 0xA001;
} else {
crc >>= 1;
}
}
}
uint8_t lCRCLo = LOWBYTE(crc);
uint8_t lCRCHi = HIGHBYTE(crc);
if (aCheck) {
return (aBuffer[aLength] == lCRCLo) && (aBuffer[aLength+1] == lCRCHi);
} else {
aBuffer[aLength] = lCRCLo;
aBuffer[aLength+1] = lCRCHi;
return true;
}
}
/*
send a request message to execute ModBus function 0x04
*/
LeddarOne_Status AP_RangeFinder_LeddarOne::send_request(void)
{
uint8_t data_buffer[10] = {0};
uint8_t i = 0;
uint32_t nbytes = uart->available();
// clear buffer
while (nbytes-- > 0) {
uart->read();
if (++i > 250) {
return LEDDARONE_ERR_SERIAL_PORT;
}
}
// Modbus read input register (function code 0x04)
data_buffer[0] = LEDDARONE_DEFAULT_ADDRESS;
data_buffer[1] = 0x04;
data_buffer[2] = 0;
data_buffer[3] = 20;
data_buffer[4] = 0;
data_buffer[5] = 10;
// CRC16
CRC16(data_buffer, 6, false);
// write buffer data with CRC16 bits
for (i=0; i<8; i++) {
uart->write(data_buffer[i]);
}
uart->flush();
return LEDDARONE_OK;
}
/*
parse a response message from Modbus
*/
LeddarOne_Status AP_RangeFinder_LeddarOne::parse_response(uint8_t &number_detections)
{
uint8_t data_buffer[25] = {0};
uint32_t start_ms = AP_HAL::millis();
uint32_t len = 0;
uint8_t i;
uint8_t index_offset = 11;
// read serial
while (AP_HAL::millis() - start_ms < 10) {
uint32_t nbytes = uart->available();
if (len == 25 && nbytes == 0) {
break;
} else {
for (i=len; i<nbytes+len; i++) {
if (i >= 25) {
return LEDDARONE_ERR_BAD_RESPONSE;
}
data_buffer[i] = uart->read();
}
start_ms = AP_HAL::millis();
len += nbytes;
}
}
if (len != 25) {
return LEDDARONE_ERR_BAD_RESPONSE;
}
// CRC16
if (!CRC16(data_buffer, len-2, true)) {
return LEDDARONE_ERR_BAD_CRC;
}
// number of detections
number_detections = data_buffer[10];
// if the number of detection is over or zero , it is false
if (number_detections > LEDDARONE_DETECTIONS_MAX || number_detections == 0) {
return LEDDARONE_ERR_NUMBER_DETECTIONS;
}
memset(detections, 0, sizeof(detections));
sum_distance = 0;
for (i=0; i<number_detections; i++) {
// construct data word from two bytes and convert mm to cm
detections[i] = (static_cast<uint16_t>(data_buffer[index_offset])*256 + data_buffer[index_offset+1]) / 10;
sum_distance += detections[i];
index_offset += 4;
}
return LEDDARONE_OK;
}