mirror of https://github.com/ArduPilot/ardupilot
131 lines
4.5 KiB
C++
131 lines
4.5 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_LightWareSerial.h"
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#include <AP_HAL/AP_HAL.h>
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#include <ctype.h>
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extern const AP_HAL::HAL& hal;
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#define LIGHTWARE_DIST_MAX_CM 10000
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#define LIGHTWARE_OUT_OF_RANGE_ADD_CM 100
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// read - return last value measured by sensor
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bool AP_RangeFinder_LightWareSerial::get_reading(uint16_t &reading_cm)
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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 = 0; // sum of all readings taken
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uint16_t valid_count = 0; // number of valid readings
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uint16_t invalid_count = 0; // number of invalid readings
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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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char c = uart->read();
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// use legacy protocol
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if (protocol_state == ProtocolState::UNKNOWN || protocol_state == ProtocolState::LEGACY) {
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if (c == '\r') {
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linebuf[linebuf_len] = 0;
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const float dist = strtof(linebuf, nullptr);
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if (!is_negative(dist)) {
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sum += dist;
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valid_count++;
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// if still determining protocol update legacy valid count
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if (protocol_state == ProtocolState::UNKNOWN) {
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legacy_valid_count++;
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}
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} else {
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invalid_count++;
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}
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linebuf_len = 0;
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} else if (isdigit(c) || c == '.' || c == '-') {
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linebuf[linebuf_len++] = c;
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if (linebuf_len == sizeof(linebuf)) {
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// too long, discard the line
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linebuf_len = 0;
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}
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}
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}
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// use binary protocol
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if (protocol_state == ProtocolState::UNKNOWN || protocol_state == ProtocolState::BINARY) {
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bool msb_set = BIT_IS_SET(c, 7);
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if (msb_set) {
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// received the high byte
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high_byte = c;
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high_byte_received = true;
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} else {
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// received the low byte which should be second
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if (high_byte_received) {
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const float dist = (high_byte & 0x7f) << 7 | (c & 0x7f);
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if (!is_negative(dist)) {
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sum += dist * 0.01f;
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valid_count++;
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// if still determining protocol update binary valid count
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if (protocol_state == ProtocolState::UNKNOWN) {
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binary_valid_count++;
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}
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} else {
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invalid_count++;
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}
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}
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high_byte_received = false;
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}
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}
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}
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// protocol set after 10 successful reads
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if (protocol_state == ProtocolState::UNKNOWN) {
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if (binary_valid_count > 10) {
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protocol_state = ProtocolState::BINARY;
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} else if (legacy_valid_count > 10) {
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protocol_state = ProtocolState::LEGACY;
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}
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}
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uint32_t now = AP_HAL::millis();
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if (last_init_ms == 0 ||
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(now - last_init_ms > 1000 &&
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now - state.last_reading_ms > 1000)) {
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// send enough serial transitions to trigger LW20 into serial
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// mode. It starts in dual I2C/serial mode, and wants to see
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// enough transitions to switch into serial mode.
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uart->write("www\r\n");
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last_init_ms = now;
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} else {
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uart->write('d');
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}
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// return average of all valid readings
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if (valid_count > 0) {
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reading_cm = 100 * sum / valid_count;
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return true;
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}
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// all readings were invalid so return out-of-range-high value
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if (invalid_count > 0) {
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reading_cm = MIN(MAX(LIGHTWARE_DIST_MAX_CM, max_distance_cm() + LIGHTWARE_OUT_OF_RANGE_ADD_CM), UINT16_MAX);
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return true;
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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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