add CRC in receiver
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416f67d4ae
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@ -19,7 +19,6 @@
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* they are then stored in an InfluxDB time series database using the HTTP API
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* they are then stored in an InfluxDB time series database using the HTTP API
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* to send values to the database the curl library is required
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* to send values to the database the curl library is required
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*/
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*/
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#include <unistd.h>
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#include <unistd.h>
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#include <string.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdio.h>
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@ -29,6 +28,9 @@
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#include <RF24/RF24.h> // http://tmrh20.github.io/RF24 library to communicate to the nRF24L01+
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#include <RF24/RF24.h> // http://tmrh20.github.io/RF24 library to communicate to the nRF24L01+
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#include <curl/curl.h> // curl library to send the measurement data to the influxDB.
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#include <curl/curl.h> // curl library to send the measurement data to the influxDB.
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#include "aes.h" // AES library (from tiny-AES128-C)
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#include "aes.h" // AES library (from tiny-AES128-C)
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#include "crc16.h" // CRC Computations (from AVR libc)
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//#define DEBUG 1
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// Setup for RPi B1 GPIO 22 CE and CE0 CSN with SPI Speed @ 8Mhz
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// Setup for RPi B1 GPIO 22 CE and CE0 CSN with SPI Speed @ 8Mhz
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RF24 radio(RPI_V2_GPIO_P1_22, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_8MHZ);
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RF24 radio(RPI_V2_GPIO_P1_22, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_8MHZ);
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@ -77,32 +79,76 @@ int main(int argc, char** argv){
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uint8_t size = radio.getDynamicPayloadSize();
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uint8_t size = radio.getDynamicPayloadSize();
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radio.read(&payload,size);
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radio.read(&payload,size);
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/*
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#ifdef DEBUG
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printf("got %d bytes:",size);
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printf("got %d bytes:",size);
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for (uint8_t i=0; i<size; i++) {
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for (uint8_t i=0; i<size; i++) {
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printf(" %02x",payload[i]);
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printf(" %02x",payload[i]);
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}
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}
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printf("\n");
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printf("\n");
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*/
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#endif
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// got through payload
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// got through payload
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if (size!=1+16) {
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if (size!=1+4*4+1) {
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#ifdef DEBUG
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printf("wrong size: expected %d, got %d\n",18,size);
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#endif
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continue;
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continue;
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}
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}
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uint8_t id = payload[0]; // the meter id (0 is myself, used for unknown source)
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uint8_t id = payload[0]; // the meter id (0 is myself, used for unknown source)
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float voltage, current, power, energy; // the values coming from the meter
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if (id!=1) { // there is only one source for power measurement
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#ifdef DEBUG
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printf("wrong id: expected %d, got %d\n",1,id);
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#endif
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continue;
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}
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uint8_t values[16]; // the encrypted values block
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uint8_t values[16]; // the encrypted values block
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AES128_ECB_decrypt(&payload[1], key, values); // decrypt payload
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AES128_ECB_decrypt(&payload[1], key, values); // decrypt values
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#ifdef DEBUG
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printf("decrypted values:");
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for (uint8_t i=0; i<sizeof(values); i++) {
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printf(" %02x",values[i]);
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}
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printf("\n");
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#endif
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for (uint8_t i=0; i<sizeof(values) && i<sizeof(iv); i++) { // use CBC mode
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for (uint8_t i=0; i<sizeof(values) && i<sizeof(iv); i++) { // use CBC mode
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values[i] ^= iv[i]; // XOR with last IV
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values[i] ^= iv[i]; // XOR with last IV
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}
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}
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#ifdef DEBUG
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printf("XORed values:");
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for (uint8_t i=0; i<sizeof(values); i++) {
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printf(" %02x",values[i]);
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}
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printf("\n");
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#endif
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memcpy(iv,&payload[1],sizeof(iv)); // save next IV
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memcpy(iv,&payload[1],sizeof(iv)); // save next IV
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// check CRC of plain values
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uint8_t crc = 0;
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for (uint8_t i = 0; i < sizeof(values); i++) {
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crc = _crc_ibutton_update(crc, values[i]); // calculate CRC
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}
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crc = _crc_ibutton_update(crc, payload[17]); // this is the CRC
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if (crc) { // wrong key or IV
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#ifdef DEBUG
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printf("wrong CRC: expected %d, got %d\n",payload[17],crc);
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#endif
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continue;
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}
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uint8_t invalid[sizeof(values)]; // used to indicate that the values are invalid
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memset(invalid,0xff,sizeof(invalid)); // 0xff... is the invalid value
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if (memcmp(invalid,values,sizeof(values))==0) { // values are invalid
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#ifdef DEBUG
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printf("invalid values\n");
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#endif
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continue;
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}
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// read values
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float voltage, current, power, energy; // the values coming from the meter
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memcpy(&voltage,&values[0],4); // read voltage
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memcpy(&voltage,&values[0],4); // read voltage
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memcpy(¤t,&values[4],4); // read current
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memcpy(¤t,&values[4],4); // read current
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memcpy(&power,&values[8],4); // read power
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memcpy(&power,&values[8],4); // read power
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memcpy(&energy,&values[12],4); // read energy
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memcpy(&energy,&values[12],4); // read energy
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printf("meter: %d, voltage: %f V, current: %f A, power: %f W, energy: %f Wh\n",id,voltage,current,power,energy);
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printf("meter: %d, voltage: %f V, current: %f A, power: %f W, energy: %f Wh\n",id,voltage,current,power,energy);
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// submit values to database
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if (curl) {
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if (curl) {
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CURLcode res = CURLE_OK; // curl response
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CURLcode res = CURLE_OK; // curl response
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char post[128*4] = {0}; // string to submit data to DB using POST request
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char post[128*4] = {0}; // string to submit data to DB using POST request
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