So I think I'm to the point with my fermentation temperature controller that I'm finally happy with the hardware. I picked an SD card reader breakout so I don't have to string wires over to my wifi shield anymore, and also added a DS1307 real time clock breakout. My plan is to keep a full time-temperature log for each beer I make with all the time/date information, and store it for reference so that I know if something went wrong during fermentation that could be attributed to temperature variations.
A couple other tweaks:
I had been setting the setpoint temperature using a potentiometer, but that was way too touchy and would jump around due to voltage variation on the ADC. Instead, the two small buttons you can see on the breadboard near the top of that image (between the RTC and Boarduino) are wired to the two hardware interrupt pins. It starts up with a default setpoint of 68F, and then I can increase or decrease one degree instantly by pushing these buttons. I think I many eventually add a switch that will change between F and C mode on the setpoint, however for C I think I'll have to make things increment by a fractional increment instead of 1.
Some extra bling - on the breadboard there is a blue and red LED. The blue lights up while the freezer is running, and the red lights up while the heater is on. For the final version of this, I picked up a couple of pushbuttons, one red, and one blue, both of which have LEDs inside them. Thus, they'll be dual function for increasing/decreasing temperature as well as indicators for when things are on/off.
Now everything can be easily mounted in the small project box I purchased for this some time back! I just need to figure out the cleverest way, including having the SD card breakout accessible from the outside. I think I'm also going to use a couple of stereo mini-plugs and jacks in order to connect the relay box and string of one-wire sensors into the final product. #arduino #homebrewing