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Some Problems with DS1307 RTC

Saeedk9574

New Member
Hi Everyone,
It has been a few days that I have been struggling with DS1307 RTC and I have some questions and problems. I should mention I had tested a library for ds1307 on its prepared module, then I decided to make the circuit separately with its components. These are the ds1307 module pic and its circuit diagram. In addition I attached ds1307 and its module datasheet here. However, there was not appropriate datasheet for its module.
View attachment 187789View attachment 187790

1. Based on the datasheet ds1307 has 56B nvSRAM, so my first question is what is the usage of eeprom in this module? is it necessary to use eeprom on my board or not?

2. Second, I have a very big problem. After creating this circuit on PCB, it works correctly when the board is fixed on its place. But sometimes by a simple movement of the board the timer gets stuck and sometimes it works well. My first guess was the crystal oscillator stops working by moving the board. But then I decided to touch crystal by my hand to test it and it was OK. I do not know where is the problem.

3. I should mention the only difference between the module and my circuit is the type of eeprom. Module has a 32K eeprom (24c32), but I used a 1k eeprom (24AA01). Can this difference affect the performance. I still do not know the usage of eeprom here.
 

Attachments

  • DS1307-1513036.pdf
    214.7 KB · Views: 119
  • tiny_rtc.pdf
    806 KB · Views: 109
You don't need an additional EEPROM (24C32). The DS1307 contains 56 bytes of battery backed ram (but still Non Volatile). The two lots of memory are not connected. They just exist on the same bus. You address whichever one you want to address. The DS is at address 0x68, memory (24Lxxx) is normally 0x50 to 0x5f. Note these addresses need doubleing in order for the bottom bit to be the R/W bit.

Mike.
 
Have you used the correct specification of 32KHz crystal, and are the connections to the IC extremely short?
There are many different specifications, and stray capacitance or nearby signal tracks can affect the oscillator operation.

See the info in this app note, especially page 4 & 5:
Yes, its a timer crystal. and timer works precisely. What I am sure about is the simple movement of board disrupt timer. Probably a connection gets disconnected by movement
 

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