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padbol
Joined: 25 Apr 2011
Posts: 11
Location: Belgium
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| DS1307, turning crystal on |
 Posted: Thu May 31, 2012 6:04 am |
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Hello,
I'm experiencing a weird issue with my RTC which seems to not start the oscillator after a powering down.
I'm using the initialisation source code provided below that I found here : http://www.ccsinfo.com/forum/viewtopic.php?t=23255
| Code: |
void ds1307_init(void)
{
BYTE seconds = 0;
i2c_start();
i2c_write(0xD0); // WR to RTC
i2c_write(0x00); // REG 0
i2c_start();
i2c_write(0xD1); // RD from RTC
seconds = bcd2bin(i2c_read(0)); // Read current "seconds" in DS1307
i2c_stop();
seconds &= 0x7F;
delay_us(3);
i2c_start();
i2c_write(0xD0); // WR to RTC
i2c_write(0x00); // REG 0
i2c_write(bin2bcd(seconds)); // Start oscillator with current "seconds value
i2c_start();
i2c_write(0xD0); // WR to RTC
i2c_write(0x07); // Control Register
i2c_write(0x80); // Disable squarewave output pin
i2c_stop();
}
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When I'm turning power on, this function is called to initiate RTC. Time is displayed on a LCD which always shows 00:00:00
If I set a date OR a time, oscillator starts and time begins to run to 00:00:01 ; 00:00:02 ; ...
Does someone can help me about that problem? Using "seconds & 0x7F", oscillator should start. Isn't it?
Please note that I'm trying it without any battery. Could it be a part of the problem?
_________________
- Be the change you want to see in the world (Gandhi) - |
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drh
Joined: 12 Jul 2004
Posts: 192
Location: Hemet, California USA
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| Posted: Thu May 31, 2012 8:50 am |
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If you remove power without a battery attached, the oscillator will stop.
_________________
David |
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ezflyr
Joined: 25 Oct 2010
Posts: 1019
Location: Tewksbury, MA
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| Posted: Thu May 31, 2012 9:47 am |
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Hi,
Search the forum, there are many threads on this subject. Summary: you need the battery....
John |
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