113 lines
No EOL
3.6 KiB
C++
113 lines
No EOL
3.6 KiB
C++
/*
|
|
SG112A.cpp - SG112A Sensor Library
|
|
Copyright (c) 2020-2021, Stefan Brand
|
|
All rights reserved.
|
|
Redistribution and use in source and binary forms, with or without
|
|
modification, are permitted provided that the following conditions are met:
|
|
1. Redistributions of source code must retain the above copyright notice, this
|
|
list of conditions and the following disclaimer.
|
|
2. Redistributions in binary form must reproduce the above copyright notice,
|
|
this list of conditions and the following disclaimer in the documentation
|
|
and/or other materials provided with the distribution.
|
|
3. Neither the name of the copyright holder nor the names of its
|
|
contributors may be used to endorse or promote products derived from
|
|
this software without specific prior written permission.
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
|
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
|
|
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
|
|
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#include <Arduino.h>
|
|
#include "SG112A.h"
|
|
|
|
// Constructor - Inititalize Hardware UART
|
|
SG112A::SG112A(void) {
|
|
Serial.begin(9600);
|
|
Serial.setTimeout(READ_TIMEOUT);
|
|
}
|
|
|
|
void SG112A::getSensorData(lora_data &loradata) {
|
|
write(CMD_GET_PPM);
|
|
delay(50);
|
|
uint8_t readBytes = read();
|
|
|
|
if (readBytes > 0) {
|
|
switch(buffer[2]) {
|
|
case 0x15:
|
|
loradata.ppm = (buffer[5]*256) + buffer[4];
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Write a Command to the Sensor
|
|
void SG112A::write(byte cmd) {
|
|
uint8_t _cmd[6] = {0xAA, 0x55, cmd, 0x00, 0x00, 0x00};
|
|
uint16_t crc = crc16(_cmd, 4);
|
|
_cmd[4] = (uint8_t)(crc & 0xFF);
|
|
_cmd[5] = (uint8_t)(crc >> 8);
|
|
while (Serial.available() > 0) Serial.read();
|
|
Serial.write(_cmd, 6);
|
|
Serial.flush();
|
|
}
|
|
|
|
// Read a Sensor Response
|
|
uint8_t SG112A::read() {
|
|
// Number of returned Bytes
|
|
uint8_t ret = 0;
|
|
// Clear Internal Buffer
|
|
zeroBuffer();
|
|
|
|
// Read Available Bytes
|
|
if (Serial.available() > 0) {
|
|
ret = Serial.readBytes(buffer, SER_BUF_LEN);
|
|
}
|
|
|
|
// Check Sync Bytes
|
|
if (buffer[0] != 0xBB || buffer[1] != 0x66)
|
|
return 0;
|
|
|
|
// Check CRC of the Returned Messages
|
|
uint16_t crc = crc16(buffer, ret-2);
|
|
if (buffer[ret-1] != (uint8_t)(crc >> 8) || buffer[ret-2] != (uint8_t)(crc & 0xFF))
|
|
return 0;
|
|
|
|
return ret;
|
|
}
|
|
|
|
// Fill the Internal Buffer with Zeroes
|
|
void SG112A::zeroBuffer() {
|
|
for (int i=0; i < SER_BUF_LEN; i++)
|
|
buffer[i] = 0x00;
|
|
}
|
|
|
|
// Calculate 16Bit CRC of Messages and Commands
|
|
uint16_t SG112A::crc16(uint8_t *cmd, int len){
|
|
uint16_t ret = 0xffff;
|
|
uint16_t polynomial = 0xa001;
|
|
int shift = 0x0;
|
|
int i = 0;
|
|
for (i = len - 1; i >= 0 ; i-- ){
|
|
|
|
uint16_t code = ( uint16_t )( cmd [ len -1 - i ] & 0xff );
|
|
ret = ret^code;
|
|
shift = 0x0;
|
|
while ( shift <= 7 ){
|
|
if ( ret & 0x1 ) {
|
|
ret = ret >> 1;
|
|
ret = ret^polynomial ;
|
|
} else {
|
|
ret = ret >> 1;
|
|
}
|
|
shift++;
|
|
}
|
|
}
|
|
return ret;
|
|
} |