main.cpp

00001 #include "mbed.h"
00002 //#define ibuttonpin p21
00003 
00004 Serial pc(USBTX, USBRX);
00005 
00006 //DigitalInOut ibuttondata(ibuttonpin);
00007 DigitalInOut sensor(p21);
00008 
00009 typedef struct {
00010     unsigned char family;
00011     unsigned char serial[6];
00012     unsigned char crc;
00013     unsigned char valid;
00014 } ibuttonvalue;
00015 
00016 
00017 unsigned char crc8(unsigned char crc, unsigned char data) { //Calculate CRC8
00018     crc = crc ^ data;
00019     for (int i = 0; i < 8; i++) {
00020         if (crc & 0x01) {
00021             crc = (crc >> 1) ^ 0x8C; 
00022         } else {
00023             crc >>= 1; 
00024         }
00025     }
00026     return crc;
00027 }
00028 
00029 void OneWireReset(void) { //Generates reset on 1-wire bus
00030     sensor.output();
00031     sensor = 0;
00032     wait_us(500);
00033     sensor.input();
00034     wait_us(500);
00035 }
00036 
00037 void OneWireOutByte(unsigned char data) { //Write byte on 1-wire bus
00038     for (int n = 8;n!=0; n--) {
00039         if ((data & 0x01) == 1) {
00040             sensor.output();
00041             sensor = 0;
00042             wait_us(5);
00043             sensor.input();
00044             wait_us(60);
00045         } else {
00046             sensor.output();
00047             wait_us(60);
00048             sensor.input();
00049         }
00050         data = data >> 1;
00051     }
00052 }
00053 
00054 unsigned char OneWireReadByte(void) { //Read 1 byte from 1-wire bus
00055     unsigned char d = 0;
00056     unsigned char b;
00057     for (int n = 0; n<8; n++) {
00058         sensor.output();
00059         sensor = 0;
00060         wait_us(5);
00061         sensor.input();
00062         wait_us(5);
00063         b = sensor;
00064         wait_us(50);
00065         d = (d >> 1) | (b << 7);
00066     }
00067     return d;
00068 }
00069 
00070 ibuttonvalue DetectiButton(void) { //Function to detect an iButton en give back its contents
00071     ibuttonvalue detect;
00072     unsigned char crc = 0;
00073     OneWireReset();
00074     OneWireOutByte(0x33); //Read Rom cmd
00075     detect.family = OneWireReadByte();
00076     crc = crc8(crc, detect.family);
00077     if (detect.family == 0x00 || detect.family == 0xFF) {
00078         detect.valid = 0;
00079         return detect; //No iButton detected
00080     }
00081     for (int i = 0; i <6; i++) {
00082         detect.serial[i] = OneWireReadByte();
00083         crc = crc8(crc, detect.serial[i]);
00084     }
00085     detect.crc = OneWireReadByte();
00086     if (crc == detect.crc) { //If CRC is valid: set valid flag to 1
00087         detect.valid = 1;
00088     }
00089     return detect;
00090 }
00091 
00092 //LocalFileSystem local("local");
00093 
00094 int main() {
00095 
00096 //FILE *fp = fopen("/local/out.txt", "rw");
00097 
00098     ibuttonvalue detected; 
00099     int i;   
00100     while(1) {
00101         detected = DetectiButton();
00102         if (detected.valid == 1) { //Test valid flag
00103             pc.printf("iButton Family: %X Serial: ", detected.family);
00104             for (i=6-1; i>=0; i--) {
00105                 pc.printf("%X", detected.serial[i]);
00106                // fprintf(fp, "Serial: %X", detected.serial[i]);
00107                
00108             }
00109             pc.printf(" CRC: %X\n", detected.crc);
00110        }//fclose(fp);
00111     }
00112 }