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SG112A: Add CRC Check for Sensor Messages, Code Cleanup, Comments

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seiichiro 2021-02-03 18:28:03 +01:00
parent 493a466a90
commit 8578801edf
2 changed files with 76 additions and 10 deletions
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45
lib/SG112A/SG112A.cpp
View file

@ -1,6 +1,33 @@
/*
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 <Arduino.h>
#include "SG112A.h" #include "SG112A.h"
// Constructor - Inititalize Hardware UART
SG112A::SG112A(void) { SG112A::SG112A(void) {
Serial.begin(9600); Serial.begin(9600);
Serial.setTimeout(READ_TIMEOUT); Serial.setTimeout(READ_TIMEOUT);
@ -20,6 +47,7 @@ void SG112A::getSensorData(lora_data &loradata) {
} }
} }
// Write a Command to the Sensor
void SG112A::write(byte cmd) { void SG112A::write(byte cmd) {
uint8_t _cmd[6] = {0xAA, 0x55, cmd, 0x00, 0x00, 0x00}; uint8_t _cmd[6] = {0xAA, 0x55, cmd, 0x00, 0x00, 0x00};
uint16_t crc = crc16(_cmd, 4); uint16_t crc = crc16(_cmd, 4);
@ -30,26 +58,37 @@ void SG112A::write(byte cmd) {
Serial.flush(); Serial.flush();
} }
// Read a Sensor Response
uint8_t SG112A::read() { uint8_t SG112A::read() {
// Number of returned Bytes
uint8_t ret = 0; uint8_t ret = 0;
// Clear Internal Buffer
zeroBuffer(); zeroBuffer();
// Read Available Bytes
if (Serial.available() > 0) { if (Serial.available() > 0) {
ret = Serial.readBytes(buffer, SER_BUF_LEN); ret = Serial.readBytes(buffer, SER_BUF_LEN);
} }
if (buffer[0] != 0xBB && buffer[1] != 0x66) // Check Sync Bytes
ret = 0; if (buffer[0] != 0xBB || buffer[1] != 0x66)
return 0;
// TODO: Do CRC Check Here // 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; return ret;
} }
// Fill the Internal Buffer with Zeroes
void SG112A::zeroBuffer() { void SG112A::zeroBuffer() {
for (int i=0; i < SER_BUF_LEN; i++) for (int i=0; i < SER_BUF_LEN; i++)
buffer[i] = 0x00; buffer[i] = 0x00;
} }
// Calculate 16Bit CRC of Messages and Commands
uint16_t SG112A::crc16(uint8_t *cmd, int len){ uint16_t SG112A::crc16(uint8_t *cmd, int len){
uint16_t ret = 0xffff; uint16_t ret = 0xffff;
uint16_t polynomial = 0xa001; uint16_t polynomial = 0xa001;

37
lib/SG112A/SG112A.h
View file

@ -1,17 +1,44 @@
/*
SG112A.h - 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.
*/
#ifndef SG112A_H #ifndef SG112A_H
#define SG112A_H #define SG112A_H
// Data Structure for the LoRa Packet
struct lora_data { struct lora_data {
uint8_t bat; uint8_t bat;
int16_t ppm; int16_t ppm;
} __attribute__ ((packed)); } __attribute__ ((packed));
#define READ_TIMEOUT 500 #define READ_TIMEOUT 500 // Timeout for Serial Communication
#define SER_BUF_LEN 16 #define SER_BUF_LEN 16 // Length of the Internal Serial Message Buffer
#define CMD_GET_VER 0x10 #define CMD_GET_VER 0x10 // Get Sensor Version
#define CMD_GET_SER 0x12 #define CMD_GET_SER 0x12 // Get Sensor Serial
#define CMD_GET_PPM 0x14 #define CMD_GET_PPM 0x14 // Get Current PPM Reading
class SG112A { class SG112A {
private: private: