66 lines
1.5 KiB
C
66 lines
1.5 KiB
C
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/select.h>
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float getTempByDev(char *devName);
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int main(int argc, char *argv[])
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{
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if (argc == 2)
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{
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char * ch = argv[1];
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// int gpio = atoi(ch);
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char * name = "/dev/ds18b20-";
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char devName[16];
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strcpy(devName, name);
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strcat(devName, ch);
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float t223 = getTempByDev(devName);
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printf("%.4f", t223);
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}
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else
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{
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printf("-1");
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}
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return 0;
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}
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float getTempByDev(char *devName)
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{
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int fd;
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unsigned char result[2] = {0};
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unsigned int hightBitValue = 0;
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unsigned int lowBitValue = 0;
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float p = 0.0625;
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float value = 1024.0f;
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fd = open(devName, 0);
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if (fd >= 0)
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{
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int i = read(fd, &result, sizeof(&result));
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if (i >= 0)
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{
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// printf("%xH-%xH\n", result[1], result[0]);
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hightBitValue = result[1];
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lowBitValue = result[0];
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hightBitValue <<= 8;
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hightBitValue = hightBitValue + lowBitValue;
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if ((result[1] & 0xf8))
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{
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// printf("aaa\n");
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hightBitValue = ~hightBitValue + 1;
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value = hightBitValue * p * -1;
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}
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else
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{
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value = hightBitValue * p;
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}
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}
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close(fd);
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}
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return value;
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}
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