I want to include an RTC in a greenhouse controller. It will need a display I think and certainly some sort of interface. Has anyone ideas on this? Am I trying to reinvent the wheel? It's a pity these forums aren't searchable.
You can search the forum... go to google and use it with the term:
search phrase site: forum.arduino.cc
A 16x2 LCD display is probably the most useful, simple and inexpensive type. Get one with a serial (i2c) interface already fitted. They cost a little more but worth it for simplicity of wiring. You can get 20x4 displays also if you need to display more data, but they do cost more.
For the interface, a pot and a pushbutton (maybe 2) makes for a flexible arrangement for choosing menu options and entering values.
For the RTC, I recommend a module based on ds3231, rather than the more common ds1307. It is more accurate over the long term, is temperature compensated (a good idea in a greenhouse) and has a built-in temperature sensor you can read from your sketch.
Your circuit will need to be carefully protected from the heat and humidity!
I agree with PaulRB.
I have used Deal Extreme PtNo 222910 RTC and PtNo 216865 LCD1602 I2C interface. Cheap and works well.