Real Time Clock Boards
When building an environment logger, it is often useful to have the date and time.
Parallax offers three options:
The original unit from WaveShare, DS1302 is ok but if left off for a period of time losses time.
The second unit is DS3231 which is good at keeping time even when powered off. The problem is it's takes up a lot of room. The battery is huge.
The current unit is P2 RTC. Now this unit is small and has a very small battery. The problem is that it seems to be only built for the P2. To use it with a P1 you need to solder some wires on or use pins and place them in the four positions needed to make it work. It looks like they had space left over so they could have added a QWIIC connector and made it easy to hookup instead of the hole in the board.
The other problem is it doesn't say how long it will take to charge that battery since it's a rechargeable battery or how long it will last. Also the price is a little more than the other units even though it seems to have fewer components. Who knows with the chip shortage today what it costs.
Anyway the driver to run this unit has the same address as the DS3231 and even the register values are kind of the same. The only difference is how it uses the battery and some added alarm functions.
In all I like this unit due to its size and ease of use.