I went through a youtube video on understanding I2C and how I can use it with Arduino. One part of the video that completely went over my head was the part when they are using the register to access hr,min, and sec. I do not understand how he came up with the hex codes the way he did. Here is the da…

I2C and DS1307 real-time clock IC

nickgammon March 28, 2012, 8:42pm 3

What video? Anyway as I recall the DS1307 uses Binary-coded decimal (BCD) ... Google that.

So in your examples, 0x55 would be 55 seconds, and 0x59 would be 59 minutes.

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