Diff: main.cpp

Revision:

0:39cce56e485b

Child:

1:d6732fa1e5f8

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat Feb 12 11:00:05 2011 +0000
@@ -0,0 +1,102 @@
+#include "mbed.h"
+#define ibuttonpin p20
+
+Serial pc(USBTX, USBRX);
+
+DigitalInOut ibuttondata(ibuttonpin);
+
+typedef struct {
+    unsigned char family;
+    unsigned char serial[6];
+    unsigned char crc;
+    unsigned char valid;
+} ibuttonvalue;
+
+
+unsigned char crc8(unsigned char crc, unsigned char data) { //Calculate CRC8
+    crc = crc ^ data;
+    for (int i = 0; i < 8; i++) {
+        if (crc & 0x01) {
+            crc = (crc >> 1) ^ 0x8C; 
+        } else {
+            crc >>= 1; 
+        }
+    }
+    return crc;
+}
+
+void OneWireReset(void) { //Generates reset on 1-wire bus
+    ibuttondata.output();
+    ibuttondata = 0;
+    wait_us(500);
+    ibuttondata.input();
+    wait_us(500);
+}
+
+void OneWireOutByte(unsigned char data) { //Write byte on 1-wire bus
+    for (int n = 8;n!=0; n--) {
+        if ((data & 0x01) == 1) {
+            ibuttondata.output();
+            ibuttondata = 0;
+            wait_us(5);
+            ibuttondata.input();
+            wait_us(60);
+        } else {
+            ibuttondata.output();
+            wait_us(60);
+            ibuttondata.input();
+        }
+        data = data >> 1;
+    }
+}
+
+unsigned char OneWireReadByte(void) { //Read 1 byte from 1-wire bus
+    unsigned char d = 0;
+    unsigned char b;
+    for (int n = 0; n<8; n++) {
+        ibuttondata.output();
+        ibuttondata = 0;
+        wait_us(5);
+        ibuttondata.input();
+        wait_us(5);
+        b = ibuttondata;
+        wait_us(50);
+        d = (d >> 1) | (b << 7);
+    }
+    return d;
+}
+
+ibuttonvalue DetectiButton(void) { //Function to detect an iButton en give back its contents
+    ibuttonvalue detect;
+    unsigned char crc = 0;
+    OneWireReset();
+    OneWireOutByte(0x33); //Read Rom cmd
+    detect.family = OneWireReadByte();
+    crc = crc8(crc, detect.family);
+    if (detect.family == 0x00 || detect.family == 0xFF) {
+        detect.valid = 0;
+        return detect; //No iButton detected
+    }
+    for (int i = 0; i <6; i++) {
+        detect.serial[i] = OneWireReadByte();
+        crc = crc8(crc, detect.serial[i]);
+    }
+    detect.crc = OneWireReadByte();
+    if (crc == detect.crc) { //If CRC is valid: set valid flag to 1
+        detect.valid = 1;
+    }
+    return detect;
+}
+int main() {
+    ibuttonvalue detected;    
+    while(1) {
+        detected = DetectiButton();
+        if (detected.valid == 1) { //Test valid flag
+            pc.printf("iButton Family: %X Serial: ", detected.family);
+            for (int i = 0; i < 6; i++) {
+                pc.printf("%X", detected.serial[i]);
+            }
+            pc.printf(" CRC: %X\n", detected.crc);
+        }
+    }
+}