RTC module operated by batteries.

[EngIntoHW]

Hello.

I'd like to integrate a batteries-operated RTC (real-time clock) module in my system, and to have it communicating with a 8051 Uc.

How such communication is performed? through SPI?
How much time does it work before you have to switch its batteries?

Could you please recommend on such RTC module?
I'm not sure what specifications I should be aware of when looking for such module.

Regards.

 

[EngIntoHW]

I'd appreciate any help.

 

[3lectrokid]

I'd recommend a DS1307 RTC ic. It has battery backed memory that can last for years before the battery needs to be replaced. the idea is that there is a main power supply that is used to interface the chip but when the power goes the batery automaticly kicks in and carries on counting. However in this state you cannot interface to the chip

 

[EngIntoHW]

I'd recommend a DS1307 RTC ic. It has battery backed memory that can last for years before the battery needs to be replaced. the idea is that there is a main power supply that is used to interface the chip but when the power goes the batery automaticly kicks in and carries on counting. However in this state you cannot interface to the chip

Thanks a lot!
It looks very good.

The only problem is that my MCU doesnt support I2C communication, but SPI.
You know of any similar SPI-capable RTC?

 

[Pommie]

For $8 you can get a ready made module. The I²C protocol is not hard to implement in software.

Mike.

 

[EngIntoHW]

As this module is intended to be produced in large quantities, I’m looking for a low-cost solution.
It would be cheaper to purchase the chip and its peripheral parts than buying the whole module.

As for I2C, I believe it would be wiser to use SPI as the Uc supports it and does most of the work for the programmer.

 

[Pommie]

The DS1305 is an SPI device.

Mike.

 

[EngIntoHW]

Oh thanks Mike.
I appreciate your help.