mirror of https://github.com/ArduPilot/ardupilot
108 lines
3.7 KiB
C++
108 lines
3.7 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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#include "AP_RangeFinder_NoopLoop.h"
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#if AP_RANGEFINDER_NOOPLOOP_ENABLED
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#include <AP_HAL/AP_HAL.h>
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#include <AP_HAL/utility/sparse-endian.h>
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#include <ctype.h>
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extern const AP_HAL::HAL& hal;
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#define NOOPLOOP_FRAME_HEADER 0x57
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#define NOOPLOOP_FRAME_HEADER_1 0x00
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#define NOOPLOOP_FRAME_LENGTH 16
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#define NOOPLOOP_DIST_MAX_MM 8000
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// format of serial packets received from NoopLoop TOF Sense P and F lidar
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//
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// Data Bit Definition Description
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// -----------------------------------------------------------------------
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// byte 0 Frame header 0x57
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// byte 1 Function Mark 0x00
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// byte 2 (Reserved)
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// byte 3 Id id
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// byte 4-7 System time System time in ms
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// byte 8-10 Distance*1000
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// byte 11 Status Strength high 8 bits
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// byte 12-13 Signal Strength
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// byte 14 (Reserved)
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// byte 15 Checksum
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// distance returned in reading_m
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bool AP_RangeFinder_NoopLoop::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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// read any available lines from the lidar
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uint32_t nbytes = uart->available();
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while (nbytes-- > 0) {
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uint8_t c;
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if (!uart->read(c)) {
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break;
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}
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// if buffer is empty and this byte is 0x57, add to buffer
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if (linebuf_len == 0) {
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if (c == NOOPLOOP_FRAME_HEADER) {
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linebuf[linebuf_len++] = c;
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}
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} else if (linebuf_len == 1) {
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// if buffer has 1 element and this byte is 0x00, add it to buffer
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// if not clear the buffer
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if (c == NOOPLOOP_FRAME_HEADER_1) {
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linebuf[linebuf_len++] = c;
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} else {
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linebuf_len = 0;
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}
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} else {
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// add character to buffer
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linebuf[linebuf_len++] = c;
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// if buffer now has 16 items try to decode it
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if (linebuf_len == NOOPLOOP_FRAME_LENGTH) {
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// calculate checksum
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uint8_t checksum = 0;
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for (uint8_t i=0; i<NOOPLOOP_FRAME_LENGTH-1; i++) {
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checksum += linebuf[i];
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}
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// if checksum matches extract contents
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if (checksum == linebuf[NOOPLOOP_FRAME_LENGTH-1]) {
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// calculate distance
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const int32_t dist = (int32_t)(linebuf[8] << 8 | linebuf[9] << 16 | linebuf[10] << 24) / 256;
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const uint8_t valid = (linebuf[11]);
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if (dist > 0 && reading_m < NOOPLOOP_DIST_MAX_MM && valid < 255) {
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reading_m = dist * 0.001f;
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linebuf_len = 0;
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uart->discard_input();
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return true;
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}
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}
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// clear buffer
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linebuf_len = 0;
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uart->discard_input();
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}
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}
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}
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// no readings so return false
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return false;
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}
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#endif // AP_RANGEFINDER_NOOPLOOP_ENABLED
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