Jonas Skalman / Mbed 2 deprecated SenseAirLP8

Reading SenseAir LP8 CO2 sensor over bluetooth low energy

Dependencies:   BLE_API mbed nRF51822

LP8.h@4:320febe026ed, 2017-08-21 (annotated)

Committer:
jony1401
Date:
Mon Aug 21 08:44:33 2017 +0000
Revision:
4:320febe026ed
Parent:
3:933dd59ad44d 
bugfix

Who changed what in which revision?

UserRevisionLine numberNew contents of line
jony1401 0:ee3787c8e209 1 #ifndef LP8_H
jony1401 0:ee3787c8e209 2 #define LP8_H
jony1401 0:ee3787c8e209 3
jony1401 2:d02255d8c36f 4 /* To initialize the lp8 object, you need to pass a serial (tx, rx), a DigitalOut signal for the en_vbb,
jony1401 2:d02255d8c36f 5 an DigitalIn for the ready signal, DigitalOut for Reset and a timer object. */
jony1401 1:b512a405b584 6
jony1401 0:ee3787c8e209 7 class LP8
jony1401 0:ee3787c8e209 8 {
jony1401 0:ee3787c8e209 9 public:
jony1401 1:b512a405b584 10 //constructor
jony1401 2:d02255d8c36f 11 LP8(Serial &device, DigitalOut &vbb_en, DigitalIn &rdy, DigitalOut &res ,Timer &_timer):
jony1401 1:b512a405b584 12 Device(device),
jony1401 1:b512a405b584 13 VBB_EN(vbb_en),
jony1401 1:b512a405b584 14 RDY(rdy),
jony1401 2:d02255d8c36f 15 RES(res),
jony1401 1:b512a405b584 16 lp8Wait(_timer)
jony1401 1:b512a405b584 17 {
jony1401 3:933dd59ad44d 18 Device.baud(9600); //set baud rate to 9600 Hz
jony1401 3:933dd59ad44d 19 Device.format(8, SerialBase::None, 2); //set bits, parity and stop bits
jony1401 0:ee3787c8e209 20
jony1401 1:b512a405b584 21 //initialize arrays with lp8 modbus commands.
jony1401 1:b512a405b584 22 //initial startup command:
jony1401 1:b512a405b584 23 firstWrite[0] = 0xfe; //device adress
jony1401 1:b512a405b584 24 firstWrite[1] = 0x41; //write to ram
jony1401 1:b512a405b584 25 firstWrite[2] = 0x00; //
jony1401 1:b512a405b584 26 firstWrite[3] = 0x80; //starting adress
jony1401 1:b512a405b584 27 firstWrite[4] = 0x01; //nr of bytes to send
jony1401 1:b512a405b584 28 firstWrite[5] = 0x10; //calculation control byte
jony1401 1:b512a405b584 29 firstWrite[6] = 0x28; //crc low
jony1401 1:b512a405b584 30 firstWrite[7] = 0x7e; //crc high
jony1401 0:ee3787c8e209 31
jony1401 1:b512a405b584 32 //write previous sensor state to lp8, command:
jony1401 1:b512a405b584 33 stateWrite[0] = 0xfe; //device adress
jony1401 1:b512a405b584 34 stateWrite[1] = 0x41; //write to ram
jony1401 1:b512a405b584 35 stateWrite[2] = 0x00; //
jony1401 1:b512a405b584 36 stateWrite[3] = 0x80; //starting adress
jony1401 1:b512a405b584 37 stateWrite[4] = 0x18; //nr of bytes to send
jony1401 1:b512a405b584 38 stateWrite[5] = 0x20; //Calculation Control
jony1401 1:b512a405b584 39 for(int k = 6; k < 31; k++) { stateWrite[k] = 0x00; } //
jony1401 0:ee3787c8e209 40
jony1401 1:b512a405b584 41 //read request from the lp8:
jony1401 1:b512a405b584 42 stateRead[0] = 0xfe; //adress
jony1401 1:b512a405b584 43 stateRead[1] = 0x44; //read from ram
jony1401 1:b512a405b584 44 stateRead[2] = 0x00; //
jony1401 1:b512a405b584 45 stateRead[3] = 0x80; //starting adress
jony1401 1:b512a405b584 46 stateRead[4] = 0x2c; //number of bytes to read
jony1401 1:b512a405b584 47 stateRead[5] = 0x00; //crc_l
jony1401 3:933dd59ad44d 48 stateRead[6] = 0x00; //crc_h
jony1401 3:933dd59ad44d 49
jony1401 3:933dd59ad44d 50 //communication confirmation sequence (response from lp8)
jony1401 3:933dd59ad44d 51 confirmation[0] = 0xfe;
jony1401 3:933dd59ad44d 52 confirmation[1] = 0x41;
jony1401 3:933dd59ad44d 53 confirmation[2] = 0x81;
jony1401 3:933dd59ad44d 54 confirmation[3] = 0xe0;
jony1401 1:b512a405b584 55
jony1401 1:b512a405b584 56 //response buffer
jony1401 1:b512a405b584 57 for(int k = 0; k < 60; k++) { response[k] = 0x00; }
jony1401 0:ee3787c8e209 58
jony1401 1:b512a405b584 59 //variable initialization
jony1401 3:933dd59ad44d 60 co2 = 400; //
jony1401 3:933dd59ad44d 61 CRC = 0x0000; //
jony1401 2:d02255d8c36f 62
jony1401 1:b512a405b584 63 };
jony1401 0:ee3787c8e209 64
jony1401 0:ee3787c8e209 65
jony1401 2:d02255d8c36f 66 //LP8 Initialization and first message
jony1401 0:ee3787c8e209 67 bool lp8Init(){
jony1401 2:d02255d8c36f 68
jony1401 3:933dd59ad44d 69 Device.format(8, SerialBase::None, 2);
jony1401 3:933dd59ad44d 70 //Reset LP8
jony1401 3:933dd59ad44d 71 RES.write( 0 ); //reset
jony1401 3:933dd59ad44d 72 timeIt( 1.0 );
jony1401 3:933dd59ad44d 73 RES.write( 1 ); //enable
jony1401 3:933dd59ad44d 74 timeIt(0.2);
jony1401 2:d02255d8c36f 75
jony1401 2:d02255d8c36f 76 //Enable Sensor
jony1401 0:ee3787c8e209 77 VBB_EN.write( 1 ); //power on
jony1401 3:933dd59ad44d 78
jony1401 1:b512a405b584 79 //wait for rdy signal
jony1401 3:933dd59ad44d 80 timeIt( 0.30 ); //wait for lp8 rdy signal
jony1401 3:933dd59ad44d 81 // while(RDY.read() != 0 ) { /* wait for rdy to go low */}
jony1401 3:933dd59ad44d 82
jony1401 3:933dd59ad44d 83 //transmit first packet
jony1401 1:b512a405b584 84 transmitPacket(firstWrite, 8); //Send out msg (and nr of bytes) over serial line
jony1401 0:ee3787c8e209 85 Response( 4 ); //read 4 bytes response
jony1401 3:933dd59ad44d 86
jony1401 3:933dd59ad44d 87 //check response
jony1401 3:933dd59ad44d 88 if ( responseCompare() != true){
jony1401 3:933dd59ad44d 89 //VBB_EN.write( 0 );
jony1401 3:933dd59ad44d 90 return false;
jony1401 3:933dd59ad44d 91 }
jony1401 3:933dd59ad44d 92
jony1401 1:b512a405b584 93 //compute crc
jony1401 0:ee3787c8e209 94 CRC = modbusCrc(stateRead, 5);
jony1401 3:933dd59ad44d 95
jony1401 1:b512a405b584 96 //add crc value to the transmit package
jony1401 1:b512a405b584 97 stateRead[5] = (uint8_t)CRC; //crc_l
jony1401 1:b512a405b584 98 stateRead[6] = (uint8_t)(CRC >> 8); //crc_h
jony1401 3:933dd59ad44d 99
jony1401 1:b512a405b584 100 //wait for rdy
jony1401 3:933dd59ad44d 101 timeIt( 0.20 ); //
jony1401 3:933dd59ad44d 102 // while(RDY.read() != 1 ) { /*wait for rdy to go high */}
jony1401 3:933dd59ad44d 103
jony1401 0:ee3787c8e209 104 transmitPacket(stateRead, 7); //transmit packet
jony1401 3:933dd59ad44d 105 Response( 49 ); //get sensor state and co2 value(s)
jony1401 1:b512a405b584 106 VBB_EN.write( 0 ); //power off lp8
jony1401 2:d02255d8c36f 107
jony1401 3:933dd59ad44d 108 return true;
jony1401 0:ee3787c8e209 109 };
jony1401 0:ee3787c8e209 110
jony1401 1:b512a405b584 111 //send subsequent messages to the lp8
jony1401 3:933dd59ad44d 112 bool lp8Talk(uint8_t inc_ccByte){
jony1401 2:d02255d8c36f 113
jony1401 3:933dd59ad44d 114 static const uint8_t A[] = {0xFE,0x41,0x00,0x80,0x20,0x00,0x00,0x02,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
jony1401 3:933dd59ad44d 115 0x00,0x7F,0xFF,0x00,0x00,0x95,0xED,0x00,0x03,0x29,0x00,0x27,0x8C, 0xf5, 0x63};
jony1401 3:933dd59ad44d 116
jony1401 3:933dd59ad44d 117 Device.format(8, SerialBase::None, 2);
jony1401 0:ee3787c8e209 118 //transfer previous sensor state to the new msg out
jony1401 0:ee3787c8e209 119 for (int u = 4; u < 23+4; u++) {
jony1401 0:ee3787c8e209 120 stateWrite[u+2] = response[u];
jony1401 0:ee3787c8e209 121 }
jony1401 3:933dd59ad44d 122 //Set Calibration Control Byte (see end of page for explantion),
jony1401 3:933dd59ad44d 123 /* remove this statement if you want to be able to send anything to lp8 calculation control */
jony1401 3:933dd59ad44d 124 if( inc_ccByte != 0x20 ){ /* 0x52 is "simple recalibration, needs only one sample */
jony1401 3:933dd59ad44d 125 stateWrite[5] = inc_ccByte;
jony1401 3:933dd59ad44d 126 }
jony1401 3:933dd59ad44d 127 else {
jony1401 3:933dd59ad44d 128 stateWrite[5] = 0x20;
jony1401 3:933dd59ad44d 129 }
jony1401 3:933dd59ad44d 130
jony1401 3:933dd59ad44d 131
jony1401 0:ee3787c8e209 132 //compute new crc value
jony1401 3:933dd59ad44d 133 CRC = modbusCrc((uint8_t*)stateWrite, 29);
jony1401 3:933dd59ad44d 134
jony1401 0:ee3787c8e209 135 //add new crc value to send list
jony1401 0:ee3787c8e209 136 stateWrite[29] = (uint8_t)CRC;
jony1401 0:ee3787c8e209 137 stateWrite[30] = (uint8_t)(CRC >> 8);
jony1401 2:d02255d8c36f 138
jony1401 0:ee3787c8e209 139 //initialize new transfer sequence
jony1401 0:ee3787c8e209 140 VBB_EN.write( 1 ); //power on sensor
jony1401 3:933dd59ad44d 141
jony1401 2:d02255d8c36f 142 timeIt( 0.35 );
jony1401 3:933dd59ad44d 143 // while(RDY.read() != 0 ) { /* wait for rdy */}
jony1401 3:933dd59ad44d 144
jony1401 3:933dd59ad44d 145 transmitPacket(/*(uint8_t*)A*/(uint8_t*)stateWrite, 31); //Send out msg with previous state (and nr of elements) over serial line
jony1401 3:933dd59ad44d 146 Response( 4 ); //read 4 bytes response
jony1401 3:933dd59ad44d 147
jony1401 3:933dd59ad44d 148 //compare to confirmation sequence
jony1401 3:933dd59ad44d 149 if ( responseCompare() != true){
jony1401 3:933dd59ad44d 150 //VBB_EN.write( 0 );
jony1401 3:933dd59ad44d 151 return false;
jony1401 3:933dd59ad44d 152 }
jony1401 3:933dd59ad44d 153
jony1401 0:ee3787c8e209 154 //compute crc
jony1401 0:ee3787c8e209 155 CRC = modbusCrc(stateRead, 5);
jony1401 3:933dd59ad44d 156
jony1401 0:ee3787c8e209 157 //add crc value to the read request transmit package
jony1401 0:ee3787c8e209 158 stateRead[5] = (uint8_t)CRC; //crc_l
jony1401 0:ee3787c8e209 159 stateRead[6] = (uint8_t)(CRC >> 8); //crc_h
jony1401 3:933dd59ad44d 160
jony1401 3:933dd59ad44d 161 timeIt( 0.20 );
jony1401 3:933dd59ad44d 162 // while(RDY.read() != 1 ) { /* wait for rdy to go high */}
jony1401 3:933dd59ad44d 163
jony1401 0:ee3787c8e209 164 //send read request
jony1401 0:ee3787c8e209 165 transmitPacket(stateRead, 7); //transmit packet
jony1401 3:933dd59ad44d 166
jony1401 0:ee3787c8e209 167 //read sensor response
jony1401 3:933dd59ad44d 168 Response( 49 ); //get sensor state
jony1401 3:933dd59ad44d 169 VBB_EN.write( 0 ); //power off
jony1401 3:933dd59ad44d 170
jony1401 3:933dd59ad44d 171 return true;
jony1401 0:ee3787c8e209 172 };
jony1401 1:b512a405b584 173
jony1401 2:d02255d8c36f 174 //get value from lp8 response
jony1401 2:d02255d8c36f 175 unsigned long getValue() /* CO2 Value */
jony1401 0:ee3787c8e209 176 {
jony1401 1:b512a405b584 177 int high = response[29];
jony1401 1:b512a405b584 178 int low = response[30];
jony1401 0:ee3787c8e209 179 unsigned long val = high * 256 + low;
jony1401 0:ee3787c8e209 180
jony1401 0:ee3787c8e209 181 return val;
jony1401 0:ee3787c8e209 182 }
jony1401 2:d02255d8c36f 183
jony1401 3:933dd59ad44d 184 float getTempValue()
jony1401 2:d02255d8c36f 185 {
jony1401 2:d02255d8c36f 186 int h = response[33];
jony1401 2:d02255d8c36f 187 int l = response[34];
jony1401 2:d02255d8c36f 188 unsigned long _temp = h * 256 + l;
jony1401 2:d02255d8c36f 189
jony1401 3:933dd59ad44d 190 float _tempVal = 0.01 * _temp;
jony1401 2:d02255d8c36f 191
jony1401 2:d02255d8c36f 192 return _tempVal;
jony1401 2:d02255d8c36f 193 }
jony1401 2:d02255d8c36f 194
jony1401 3:933dd59ad44d 195 /* get Vcap value for at current measurement, [35],[36] is previous Vcap value */
jony1401 2:d02255d8c36f 196 int getVcapValue(){
jony1401 2:d02255d8c36f 197
jony1401 3:933dd59ad44d 198 int hB = response[37];
jony1401 3:933dd59ad44d 199 int lB = response[38];
jony1401 2:d02255d8c36f 200 unsigned long temp = hB * 256 + lB;
jony1401 2:d02255d8c36f 201
jony1401 2:d02255d8c36f 202 return temp;
jony1401 2:d02255d8c36f 203 }
jony1401 2:d02255d8c36f 204
jony1401 2:d02255d8c36f 205 uint32_t getErrorStatus(){
jony1401 2:d02255d8c36f 206
jony1401 2:d02255d8c36f 207 uint32_t tmp = 0;
jony1401 2:d02255d8c36f 208 tmp += response[39] << (32-8);
jony1401 2:d02255d8c36f 209 tmp += response[40] << (32-16);
jony1401 2:d02255d8c36f 210 tmp += response[41] << (32-24);
jony1401 2:d02255d8c36f 211 tmp += response[42];
jony1401 2:d02255d8c36f 212
jony1401 2:d02255d8c36f 213 return tmp;
jony1401 2:d02255d8c36f 214 }
jony1401 2:d02255d8c36f 215
jony1401 2:d02255d8c36f 216 //get calculation Control byte from lp8 response
jony1401 2:d02255d8c36f 217 uint8_t getCCbyte(){
jony1401 3:933dd59ad44d 218 uint8_t rCCbyte = stateWrite[5];
jony1401 3:933dd59ad44d 219 return rCCbyte;
jony1401 2:d02255d8c36f 220 }
jony1401 2:d02255d8c36f 221
jony1401 1:b512a405b584 222
jony1401 1:b512a405b584 223 /************************************************* Helper Functions ********************************************/
jony1401 2:d02255d8c36f 224
jony1401 1:b512a405b584 225 //purge response buffer
jony1401 0:ee3787c8e209 226 void responsePurge(int bytesToPurge){
jony1401 0:ee3787c8e209 227 for (int j = 0; j < bytesToPurge; j++) {
jony1401 0:ee3787c8e209 228 response[j] = 0x00;
jony1401 0:ee3787c8e209 229 }
jony1401 3:933dd59ad44d 230 //for(int k = 6; k < 31; k++) { stateWrite[k] = 0x00; } //purge sensor state
jony1401 0:ee3787c8e209 231 };
jony1401 1:b512a405b584 232
jony1401 3:933dd59ad44d 233 //read response from lp8
jony1401 3:933dd59ad44d 234 void Response( int bytesToRead ){
jony1401 3:933dd59ad44d 235 int Count = 0;
jony1401 4:320febe026ed 236
jony1401 4:320febe026ed 237 lp8Wait.start(); /* timeout timer if something goes wrong */
jony1401 4:320febe026ed 238
jony1401 0:ee3787c8e209 239 do {
jony1401 0:ee3787c8e209 240 if(Device.readable()) {
jony1401 3:933dd59ad44d 241 response[Count] = Device.getc();
jony1401 3:933dd59ad44d 242 Count++;
jony1401 3:933dd59ad44d 243 --bytesToRead;
jony1401 0:ee3787c8e209 244 }
jony1401 0:ee3787c8e209 245 }
jony1401 4:320febe026ed 246 while( (bytesToRead > 0) || (lp8Wait.read() < 0.2 ));
jony1401 4:320febe026ed 247
jony1401 4:320febe026ed 248 lp8Wait.stop();
jony1401 4:320febe026ed 249 lp8Wait.reset();
jony1401 0:ee3787c8e209 250 };
jony1401 0:ee3787c8e209 251
jony1401 1:b512a405b584 252 //transmit data over serial lines
jony1401 0:ee3787c8e209 253 void transmitPacket(uint8_t msg[], int le ){
jony1401 0:ee3787c8e209 254 //Send out msg over serial line:
jony1401 0:ee3787c8e209 255 while(!Device.writeable() ) { /* wait for serial available*/ }
jony1401 0:ee3787c8e209 256 for(int pos = 0; pos < le; pos++) {
jony1401 0:ee3787c8e209 257 Device.putc(msg[pos]);
jony1401 0:ee3787c8e209 258 }
jony1401 0:ee3787c8e209 259
jony1401 0:ee3787c8e209 260 };
jony1401 0:ee3787c8e209 261
jony1401 1:b512a405b584 262 //timer
jony1401 2:d02255d8c36f 263 void timeIt(float timeMe){
jony1401 0:ee3787c8e209 264 //start amd stop timer...
jony1401 0:ee3787c8e209 265 lp8Wait.start();
jony1401 0:ee3787c8e209 266 while (lp8Wait.read() < timeMe ) { /* W A I T I N G */ }
jony1401 0:ee3787c8e209 267 lp8Wait.stop();
jony1401 0:ee3787c8e209 268 lp8Wait.reset();
jony1401 0:ee3787c8e209 269 };
jony1401 0:ee3787c8e209 270
jony1401 1:b512a405b584 271 // Computation for the modbus 16-bit crc
jony1401 0:ee3787c8e209 272 uint16_t modbusCrc(uint8_t buffer[], int len){
jony1401 0:ee3787c8e209 273 uint16_t crc = 0xFFFF;
jony1401 0:ee3787c8e209 274
jony1401 0:ee3787c8e209 275 for (int pos = 0; pos < len; pos++) {
jony1401 0:ee3787c8e209 276 crc ^= (uint16_t)buffer[pos]; // XOR byte into least sig. byte of crc
jony1401 0:ee3787c8e209 277
jony1401 0:ee3787c8e209 278 for (int i = 8; i != 0; i--) { // Loop over each bit
jony1401 0:ee3787c8e209 279 if ((crc & 0x0001) != 0) { // If the LSB is set
jony1401 0:ee3787c8e209 280 crc >>= 1; // shift right and XOR 0xA001
jony1401 0:ee3787c8e209 281 crc ^= 0xA001;
jony1401 0:ee3787c8e209 282 }
jony1401 0:ee3787c8e209 283 else // Else LSB is not set
jony1401 0:ee3787c8e209 284 crc >>= 1; // shift right
jony1401 0:ee3787c8e209 285 }
jony1401 0:ee3787c8e209 286 }
jony1401 0:ee3787c8e209 287 // Note, this number has low and high bytes swapped
jony1401 0:ee3787c8e209 288 return crc;
jony1401 0:ee3787c8e209 289 };
jony1401 1:b512a405b584 290
jony1401 3:933dd59ad44d 291 bool responseCompare(){
jony1401 3:933dd59ad44d 292
jony1401 3:933dd59ad44d 293 short seq = 0;
jony1401 3:933dd59ad44d 294
jony1401 3:933dd59ad44d 295 for(int j=0; j < 4; j++){
jony1401 3:933dd59ad44d 296 if(response[j] == confirmation[j]){
jony1401 3:933dd59ad44d 297 seq++;
jony1401 3:933dd59ad44d 298 }
jony1401 3:933dd59ad44d 299 }
jony1401 3:933dd59ad44d 300 //return false if check sequence fails
jony1401 3:933dd59ad44d 301 if( seq != 4 ){
jony1401 3:933dd59ad44d 302 return false;
jony1401 3:933dd59ad44d 303 }
jony1401 3:933dd59ad44d 304
jony1401 3:933dd59ad44d 305 return true;
jony1401 3:933dd59ad44d 306 }
jony1401 3:933dd59ad44d 307
jony1401 1:b512a405b584 308 //variables and buffers
jony1401 0:ee3787c8e209 309 private:
jony1401 2:d02255d8c36f 310 //pins
jony1401 0:ee3787c8e209 311 Serial &Device;
jony1401 0:ee3787c8e209 312 DigitalOut &VBB_EN;
jony1401 0:ee3787c8e209 313 DigitalIn &RDY;
jony1401 2:d02255d8c36f 314 DigitalOut &RES;
jony1401 2:d02255d8c36f 315
jony1401 0:ee3787c8e209 316 Timer &lp8Wait;
jony1401 0:ee3787c8e209 317
jony1401 1:b512a405b584 318 //msg containers
jony1401 3:933dd59ad44d 319
jony1401 0:ee3787c8e209 320 uint8_t firstWrite[8];
jony1401 3:933dd59ad44d 321 volatile uint8_t stateWrite[31];
jony1401 0:ee3787c8e209 322 uint8_t stateRead[7];
jony1401 3:933dd59ad44d 323 uint8_t confirmation[4];
jony1401 3:933dd59ad44d 324
jony1401 3:933dd59ad44d 325 volatile uint8_t response[60];
jony1401 3:933dd59ad44d 326
jony1401 2:d02255d8c36f 327 //
jony1401 2:d02255d8c36f 328 int co2; //CO2 initial value
jony1401 2:d02255d8c36f 329 int tempValue;
jony1401 0:ee3787c8e209 330 uint16_t CRC; //modbus crc value
jony1401 0:ee3787c8e209 331
jony1401 0:ee3787c8e209 332
jony1401 0:ee3787c8e209 333 };
jony1401 0:ee3787c8e209 334 #endif
jony1401 0:ee3787c8e209 335
jony1401 0:ee3787c8e209 336 /*
jony1401 1:b512a405b584 337 LP8 Modbus Communication Protocol (With no external Pressure Sensor):
jony1401 0:ee3787c8e209 338 --------------------------------------------------------------------------------
jony1401 0:ee3787c8e209 339 Initial Measurement (first read after powerup): COMMANDS:
jony1401 0:ee3787c8e209 340 --------------------------------------------------------------------------------
jony1401 0:ee3787c8e209 341 1) host powers up sensor: VBB_EN = 1
jony1401 0:ee3787c8e209 342 2) host waits until rdy signal goes low: RDY = 0;
jony1401 0:ee3787c8e209 343 3) host writes command, "write 24 bytes starting from adress 0x0080": { 0xfe, 0x41, 0x00, 0x80, 0x18, 0x10, ... [any 23 bytes] ..., CRC_low, CRC_high };
jony1401 0:ee3787c8e209 344 4) host reads response: { 0xfe, 0x41, 0x81, 0xe0 };
jony1401 0:ee3787c8e209 345 5) host waits until rdy signal goes high: RDY = 1;
jony1401 0:ee3787c8e209 346 6) host writes command "read 44 bytes starting from adress 0x0080": { 0xfe, 0x44, 0x00, 0x80, 0x2c, CRC_low, CRC_high };
jony1401 0:ee3787c8e209 347 7) host reads response: { 0xfe, 0x44, 0x2c, 0x00, SS1, SS2, ..., SS23, PP_H, PP_L, D1, D2, ..., D18, CRC_low, CRC_high };
jony1401 0:ee3787c8e209 348 8) host powers down sensor: VBB_EN = 0;
jony1401 0:ee3787c8e209 349
jony1401 0:ee3787c8e209 350 [------------------------------------------------------------------------------]
jony1401 0:ee3787c8e209 351 Optional first reading W/O pressure sensor
jony1401 0:ee3787c8e209 352 [------------------------------------------------------------------------------]
jony1401 0:ee3787c8e209 353 1) host powers up sensor: VBB_EN = 1
jony1401 0:ee3787c8e209 354 2) host waits until rdy signal goes low: RDY = 0;
jony1401 0:ee3787c8e209 355 3) host writes command, "write 24 bytes starting from adress 0x0080": { 0xfe, 0x41, 0x00, 0x80, 0x18, 0x10, 0x28, 0x7e };
jony1401 0:ee3787c8e209 356 4) host reads response: { 0xfe, 0x41, 0x81, 0xe0 };
jony1401 0:ee3787c8e209 357 5) host waits until rdy signal goes high: RDY = 1;
jony1401 0:ee3787c8e209 358 6) host writes command "read 44 bytes starting from adress 0x0080": { 0xfe, 0x44, 0x00, 0x80, 0x2c, CRC_low, CRC_high };
jony1401 0:ee3787c8e209 359 7) host reads response: { 0xfe, 0x44, 0x2c, 0x00, SS1, SS2, ..., SS23, PP_H, PP_L, D1, D2, ..., D18, CRC_low, CRC_high };
jony1401 0:ee3787c8e209 360 8) host powers down sensor: VBB_EN = 0;
jony1401 0:ee3787c8e209 361
jony1401 0:ee3787c8e209 362
jony1401 0:ee3787c8e209 363 --------------------------------------------------------------------------------
jony1401 0:ee3787c8e209 364 Subsequent readings:
jony1401 0:ee3787c8e209 365 --------------------------------------------------------------------------------
jony1401 0:ee3787c8e209 366 1) host powers up sensor: VBB_EN = 1
jony1401 0:ee3787c8e209 367 2) host waits until rdy signal goes low: RDY = 0;
jony1401 0:ee3787c8e209 368 3) host writes command, "write 24 bytes starting from adress 0x0080": { 0xfe, 0x41, 0x00, 0x80, 0x18, CC, SS1, ..., SS23, CRC_low, CRC_high };
jony1401 0:ee3787c8e209 369 4) host reads response: { 0xfe, 0x41, 0x81, 0xe0 };
jony1401 0:ee3787c8e209 370 5) host waits until rdy signal goes high: RDY = 1;
jony1401 0:ee3787c8e209 371 6) host writes command "read 44 bytes starting from adress 0x0080": { 0xfe, 0x44, 0x00, 0x80, 0x2c, CRC_low, CRC_high };
jony1401 0:ee3787c8e209 372 7) host reads response: { 0xfe, 0x44, 0x2c, 0x00, SS1, SS2, ..., SS23, PP_H, PP_L, D1, D2, ..., D18, CRC_low, CRC_high };
jony1401 0:ee3787c8e209 373 8) host powers down sensor: VBB_EN = 0;
jony1401 0:ee3787c8e209 374
jony1401 0:ee3787c8e209 375
jony1401 0:ee3787c8e209 376 --------------------------------------------------------------------------------
jony1401 1:b512a405b584 377 LP8 Background Calibration, Calculation Control Byte
jony1401 1:b512a405b584 378 --------------------------------------------------------------------------------
jony1401 1:b512a405b584 379 To calibrate the lp8, commands needs to be sent with the calculation control byte
jony1401 1:b512a405b584 380 Calculation:
jony1401 1:b512a405b584 381 CC =
jony1401 1:b512a405b584 382 0x10 Initial measurement (filters reset, ABC sample reset and other,
jony1401 1:b512a405b584 383 0x20 Subsequent measurement,
jony1401 1:b512a405b584 384 0x40 Zero calibration using unfiltered data,
jony1401 1:b512a405b584 385 0x41 Zero calibration using filtered data,
jony1401 1:b512a405b584 386 0x42 Zero calibration using unfiltered data + reset filters,
jony1401 1:b512a405b584 387 0x43 Zero calibration using filtered data + reset filters,
jony1401 1:b512a405b584 388 0x50 Background calibration using unfiltered data,
jony1401 1:b512a405b584 389 0x51 Background calibration using filtered data,
jony1401 1:b512a405b584 390 0x52 Background calibration using unfiltered data + reset filters,
jony1401 1:b512a405b584 391 0x53 Background calibration using filtered data + reset filters,
jony1401 1:b512a405b584 392 0x70 ABC (based on filtered data),
jony1401 1:b512a405b584 393 0x72 ABC (based on filtered data) + reset filters
jony1401 1:b512a405b584 394
jony1401 1:b512a405b584 395
jony1401 1:b512a405b584 396 --------------------------------------------------------------------------------
jony1401 0:ee3787c8e209 397 --------------------------------------------------------------------------------
jony1401 0:ee3787c8e209 398 CC = Calculation Control, 1 byte
jony1401 0:ee3787c8e209 399 SS = Sensor State, Sensor State, 23 bytes
jony1401 0:ee3787c8e209 400 D = Measured data and Sensor Status, 23 bytes
jony1401 0:ee3787c8e209 401 PP = Host Pressure Value
jony1401 0:ee3787c8e209 402 CRC= 16 bit CRC error check
jony1401 0:ee3787c8e209 403 --------------------------------------------------------------------------------
jony1401 0:ee3787c8e209 404 --------------------------------------------------------------------------------
jony1401 0:ee3787c8e209 405 */
jony1401 0:ee3787c8e209 406