update

ds18b20.c

@@ -122,7 +122,8 @@ void readDs18b20Data(unsigned char *value)
 
 //    local_irq_enable();
 
-    mdelay(750);
+    //mdelay(750);
+    mdelay(375);
     //msleep(750);
 
 //    local_irq_disable();
@@ -145,16 +146,18 @@ void readDs18b20Data(unsigned char *value)
 
 //    mdelay(1);
 
-  //  init_DS18B20();
+    //init_DS18B20();
     //write_char(0xB4);
     //DQ_OUT;
     //printk("%d: EC:%d", gpio_num,DQ_V);
+    //write_char(0xCC);
     //write_char(0x4E);
     //write_char(0x64);
     //write_char(0x00);
-    //write_char(0x7F);
+    //write_char(0x5F);
 
     //init_DS18B20();
+    //write_char(0xCC);
     //write_char(0x48);
 }
 

make.sh

@@ -0,0 +1 @@
+gcc   -lpthread

temp.c

@@ -2,17 +2,47 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <sys/select.h>
+#include <pthread.h>
+
+#define N  2
 
 float getTempByDev(char *devName);
+void *run(void *args);
+
+float results[N];
+pthread_t tids[N];
+char *names[] = {"/dev/ds18b20-223","/dev/ds18b20-224"};
 
 int main(int argc, char *argv[])
 {
-    float t223 = getTempByDev("/dev/ds18b20-223");
-    float t224 = getTempByDev("/dev/ds18b20-224");
-    printf("%.4f#%.4f\n", t223, t224);
+    int i = 0;
+    for (i = 0; i < N; i++)
+    {
+        pthread_create(&tids[i], NULL, run, (void*)i);
+    }
+    for (i = 0; i < N; i++)
+    {
+        pthread_join(tids[i], NULL);
+    }
+    for (i = 0; i < N; i++)
+    {
+        if (i > 0)
+        {
+            printf("#");
+        }
+        printf("%.3f", results[i]);
+    }
+    printf("\n");
     return 0; 
 }
 
+void *run(void *args)
+{
+    int ret=(int)args;
+    float res = getTempByDev(names[ret]);
+    results[ret] = res;
+}
+
 float getTempByDev(char *devName)
 {
     int fd;  
@@ -20,31 +50,34 @@ float getTempByDev(char *devName)
     unsigned int hightBitValue = 0;  
     unsigned int lowBitValue = 0;  
     float p = 0.0625;
-    float value = 1024.0f;
+    float value = 1024;
+    short count = 0;
 
     fd = open(devName, 0);  
     if (fd >= 0) 
     {
-        int i = read(fd, &result, sizeof(&result));
-        if (i >= 0)
+        do
         {
-    //        printf("%xH-%xH\n", result[1], result[0]);
-            hightBitValue = result[1];
-            lowBitValue = result[0];
-            hightBitValue <<= 8;
-            hightBitValue = hightBitValue + lowBitValue;
-            if ((result[1] & 0xf8))
+            count++;
+            int i = read(fd, &result, sizeof(&result));
+            if (i >= 0)
             {
-//                printf("aaa\n");
-                hightBitValue = ~hightBitValue + 1;
-                value = hightBitValue * p * -1;
+                hightBitValue = result[1];
+                lowBitValue = result[0];
+                hightBitValue <<= 8;
+                hightBitValue = hightBitValue + lowBitValue;
+                if ((result[1] & 0xf8))
+                {
+                    hightBitValue = ~hightBitValue + 1;
+                    value = hightBitValue * p * -1;
+                }
+                else
+                {
+                    value = hightBitValue * p;
+                }
             }
-            else
-            {
-                value = hightBitValue * p;
-            }
-
-        }  
+        }
+        while ((value < -55 || value > 125) && count < 5);  
         close(fd);
     }
     return value;