Flot Line Graph

// flot.cpp // Reading the temperature from a MCP9808, every minute, for two hours, save the // temperature, then create an HTML file utilizing the flot library // to plot the data. // Author: Jim Merkle, 08/14/2017 #include #include #include #include #include #include #include #include #include #include #include #include #include // nanosleep #define MCP9808 0x18 #ifndef u8 typedef unsigned char u8; #endif #ifndef u16 typedef unsigned short u16; #endif void msleep(int milliseconds) { //usleep(milliseconds * 1000); // limited method struct timespec ts; ts.tv_sec = milliseconds / 1000; ts.tv_nsec = (milliseconds % 1000) * 1000000; nanosleep(&ts, NULL); } // Return number of i2c_msg's transferred, else negative value for error int i2cWriteRead(int fd, int i2cAddress, u8 * pWriteData, int writeBytes, u8 * pReadData, int readBytes) { struct i2c_msg msg[2]; // declare a two i2c_msg array struct i2c_rdwr_ioctl_data i2c_data; // declare our i2c_rdwr_ioctl_data structure int msgsUsed=0; // how many i2c_msg structures are used int result; // return value from ioctl() call // Assume the first i2c_msg is used for writing if(pWriteData && writeBytes) { msg[0].addr = i2cAddress; msg[0].flags = 0; msg[0].buf = pWriteData; msg[0].len = writeBytes; msgsUsed++; // Load the second i2c_msg for receiving if the first one is used if(pReadData && readBytes) { // Load up receive msg msg[1].addr = i2cAddress; msg[1].flags = I2C_M_RD; msg[1].buf = pReadData; msg[1].len = readBytes; msgsUsed++; } } else if(pReadData && readBytes) { // Load the first i2c_msg for receiving (no transmit data) msg[0].addr = i2cAddress; msg[0].flags = I2C_M_RD; msg[0].buf = pReadData; msg[0].len = readBytes; msgsUsed++; } // Continue if we have data to transfer if(msgsUsed) { // i2c_msg array is loaded up. Now load i2c_rdwr_ioctl_data structure. i2c_data.msgs = msg; i2c_data.nmsgs = msgsUsed; // With our open file descriptor, perform I2C message transfers // This function call returns the number of i2c_msg structures processed, // or a negative error value result = ioctl(fd,I2C_RDWR,&i2c_data); if(result < 0) { printf("ioctl error: %s\n", strerror(errno)); return -2; } } else { printf("i2cWriteRead: No i2c_msg's processed\n"); } return result; // return number of i2c_msg structures processed } #define MAX_ITEMS 120 //#define MAX_ITEMS 10 // Store our 120 temperature readings into a global array float tempArray[MAX_ITEMS]; int main(int argc, char * argv[]) { printf("Content-type: text/html\n\n"); // Open the i2c bus device where the chip resides int file = open("/dev/i2c-1",O_RDWR); if(file<0) { printf("Failed to open the bus."); /* ERROR HANDLING; you can check errno to see what went wrong */ exit(1); } u8 index = 5; u8 temperatureRegs[2]; for(unsigned i = 0; i < MAX_ITEMS; i++) { i2cWriteRead(file, MCP9808, &index, 1, temperatureRegs, 2); u16 uTemp = (u16)temperatureRegs[0] << 8 | (u16)temperatureRegs[1]; uTemp <<=3; // left shift by 3, removing the flags float fTemp = (short)uTemp; fTemp /= (1<<7); // Convert into Fahrenheit float fTempf = fTemp*9/5 + 32; // Write the temperature to the console //printf("\033cTemp %0.1fF\n",fTempf); // \033c is an escape c that clears the screen printf("%0.1fF\n",fTempf); // Store the temperature data into global array tempArray[i] = fTempf; sleep(60); // delay a minute, then read again //sleep(1); // delay a second, then read again } // Close handle to I2C module, we're done with it close(file); // We have 120 points of data, create web page to display // Open file and write the data to a file FILE *dataFile = fopen("flot.html","w+"); if(!dataFile) { printf("Failed to open dataFile, \"flot.html\"."); exit(2); } fprintf(dataFile,"\n"); fprintf(dataFile,"\n"); fprintf(dataFile,"\n"); fprintf(dataFile,"\n"); fprintf(dataFile,"Flot Line Graph\n\n"); fprintf(dataFile,"\n\n"); fprintf(dataFile,"\n"); fprintf(dataFile,"\n"); fprintf(dataFile,"\n\n"); fprintf(dataFile,"\n"); fprintf(dataFile,"\n\n"); fprintf(dataFile,"\n"); fprintf(dataFile,"

\n"); fprintf(dataFile,"\n"); fprintf(dataFile,"\n"); fclose(dataFile); printf("Data collected and written to file\n"); return 0; }