mirror of https://github.com/ArduPilot/ardupilot
83 lines
2.4 KiB
C++
83 lines
2.4 KiB
C++
/*
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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driver for Lanbao PSK-CM8JL65-CC5 Lidar
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*/
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#include <AP_HAL/AP_HAL.h>
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#include "AP_RangeFinder_Lanbao.h"
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#include <AP_Math/crc.h>
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#include <stdio.h>
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extern const AP_HAL::HAL& hal;
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/*
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this sensor has no way of reporting "out of range", it will keep
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reporting distances at of around 7 to 8 meters even when pointed at
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the sky. For this reason we limit the max range to 6 meters as
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otherwise we may be giving false data
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*/
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#define LANBAO_MAX_RANGE_M 6
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// read - return last value measured by sensor
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bool AP_RangeFinder_Lanbao::get_reading(float &reading_m)
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{
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if (uart == nullptr) {
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return false;
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}
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float sum_range = 0;
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uint32_t count = 0;
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// format is: [ 0xA5 | 0x5A | distance-MSB-mm | distance-LSB-mm | crc16 ]
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// read any available lines from the lidar
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int16_t nbytes = uart->available();
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while (nbytes-- > 0) {
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int16_t b = uart->read();
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if (b == -1) {
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break;
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}
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if (buf_len == 0 && b != 0xA5) {
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// discard
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continue;
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}
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if (buf_len == 1 && b != 0x5A) {
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// discard
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if (b == 0xA5) {
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buf[0] = b;
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} else {
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buf_len = 0;
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}
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continue;
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}
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buf[buf_len++] = b;
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if (buf_len == sizeof(buf)) {
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buf_len = 0;
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uint16_t crc = (buf[5]<<8) | buf[4];
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if (crc != calc_crc_modbus(buf, 4)) {
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// bad CRC, discard
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continue;
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}
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sum_range += float((buf[2]<<8) | buf[3]) * 0.001;
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count++;
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}
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}
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if (count > 0) {
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reading_m = (sum_range / count);
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return reading_m <= LANBAO_MAX_RANGE_M?true:false;
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}
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return false;
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}
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