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Forum Index : Microcontroller and PC projects : For those who like the tiny RTC module with the battery
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 7871 |
If you link the unused pin of the PCB header to a lithium cell you have a neat system. Normally, when you plug in one of these modules, that pin is unused. They are designed to fit onto pins 1,3,5,7 and 9 of the GPIO port of a Raspberry Pi. Pin 7 is GPIO4(GPCLK0) so it has no connection. The on-board battery has an unknown life and will eventually die. Unsolder it and put a wire link between the unused pin and the battery pad closest to the connector. Now, if you plug it into a PCB with the above mod, the RTC will be powered by the PCB's lithium cell. It doesn't matter whether you plug a new or modified RTC module in, it will work without complication. It wouldn't be a good idea to plug a modified module onto a Raspberry Pi though as it would directly connect GPIO4 to 3V3. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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