Hardware Reference
In-Depth Information
23 /
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24
Read : [ S ] 0xB1 <regaddr> <rtcbuf[0]> . . . <rtcbuf[n−1]> [P]
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25
/
26 static int
27 i2c_rd_rtc(ds1307_rtc_regs
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rtc) {
28 struct i2c_rdwr_ioctl_data msgset;
29 struct i2c_msg iomsgs[2];
30 char zero = 0x00; /
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Register 0x00
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31
32 iomsgs[0].addr = 0x68; /
DS1307
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33 iomsgs[0].flags = 0; /
Write
/
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34 iomsgs[0].buf = &zero; /
Register 0x00
/
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35 iomsgs[0].len = 1;
36
37 iomsgs[1].addr = 0x68; /
DS1307
/
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38 iomsgs[1].flags = I2C_M_RD; /
Read
/
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39 iomsgs[1].buf = (char
)rtc;
40 iomsgs[1].len = size of
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rtc;
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41
42 msgset.msgs=iomsgs;
43 msgset.nmsgs=2;
44
45 return ioctl(i2c_fd,I2C_RDWR,&msgset);
46 }
47
48 /
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49
Main program :
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50
/
51 int
52 main(int argc,char
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argv) {
53 ds1307_rtc_regs rtc; /
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8 DS1307 Register Values
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54 struct tm t0, t1; /
Unix date / time values
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55 char
date_format = getenv("DS1307_FORMAT");
56 char dtbuf[256]; /
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Formatted date/time
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57 int rc; /
Return code
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58
59 /
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60
If no environment variable named DS1307_FORMAT, then
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61
set a default date/time format.
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62
/
63 if ( !date_format )
64 date_format = "%Y−%m−%d%H:%M:%S(%A)";
65
66 /
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67
Initialize I2C and clear rtc and t1 structures:
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68
/
69 i2c_init(node); /
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Initialize for I2C
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