ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_LightWareSer...

88 lines
2.8 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_RangeFinder_LightWareSerial.h"
#include <AP_HAL/AP_HAL.h>
#include <ctype.h>
extern const AP_HAL::HAL& hal;
#define LIGHTWARE_DIST_MAX_CM 10000
#define LIGHTWARE_OUT_OF_RANGE_ADD_CM 100
// read - return last value measured by sensor
bool AP_RangeFinder_LightWareSerial::get_reading(uint16_t &reading_cm)
{
if (uart == nullptr) {
return false;
}
float sum = 0; // sum of all readings taken
uint16_t valid_count = 0; // number of valid readings
uint16_t invalid_count = 0; // number of invalid readings
// read any available lines from the lidar
int16_t nbytes = uart->available();
while (nbytes-- > 0) {
char c = uart->read();
if (c == '\r') {
linebuf[linebuf_len] = 0;
const float dist = strtof(linebuf, NULL);
if (!is_negative(dist)) {
sum += dist;
valid_count++;
} else {
invalid_count++;
}
linebuf_len = 0;
} else if (isdigit(c) || c == '.' || c == '-') {
linebuf[linebuf_len++] = c;
if (linebuf_len == sizeof(linebuf)) {
// too long, discard the line
linebuf_len = 0;
}
}
}
uint32_t now = AP_HAL::millis();
if (last_init_ms == 0 ||
(now - last_init_ms > 1000 &&
now - state.last_reading_ms > 1000)) {
// send enough serial transitions to trigger LW20 into serial
// mode. It starts in dual I2C/serial mode, and wants to see
// enough transitions to switch into serial mode.
uart->write("www\r\n");
last_init_ms = now;
} else {
uart->write('d');
}
// return average of all valid readings
if (valid_count > 0) {
reading_cm = 100 * sum / valid_count;
return true;
}
// all readings were invalid so return out-of-range-high value
if (invalid_count > 0) {
reading_cm = MIN(MAX(LIGHTWARE_DIST_MAX_CM, max_distance_cm() + LIGHTWARE_OUT_OF_RANGE_ADD_CM), UINT16_MAX);
return true;
}
// no readings so return false
return false;
}