After I had enough time playing with a thermal sensor DS18b20 and the RTC DS1307 I decided to bundle them together into a single device. Another reason was the fact that the cheap Chinese clock called a day and let its electronic soul leave the nice enclosure. I considered this as an opportunity to put my stuff inside of it.

That is what I got in the end:

+1 reason is that I had a free sample of the “port expander” PCA9539, I mentioned this IC in experiment #13.