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This project is a complete replacement of widely used RTC modules DS1287, DS12887, DS12887+ originally made by Dallas and their derivatives.
Contents of this repository may be freely used for any purpose including PCB manufacturing and product selling with original copyright marking, you can use gerber files included. DV-87-12 and DV-87-12R were made in DipTrace and DV-87-12SR was made in KiCad EDA 8.0.
These are variants of boards using different IC footprint and battery holder:
Only one of R1, R2 and R3 should be installed. DS1287 pin 1 is a mode select, some motherboards do not have it working, so you can pull pin 1 up with R2 for Motorola mode or down with R3 for Intel mode. Put zero resistor in R1 if you do not know.
Original DS1287 have 21 and 22 as not-connected, so by default you do not install R4 and R5. Some motherboards are known to use RCLR signal on pin 21. Put zero resitor into R4 if motherboard have "Clear RTC" jumper. DS13* or DS14* are using both 21 and 22 pins, so you put both R4 and R5 in place.
You can use DS12885, bq3285 or bq4285 depending on what you can find and what original chip you want to replace.
None of these were used in current project except general idea.
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