Temperature & Humdity
18/01/16 16:11
This is one of my very early experiments with Arduino that succeeded in the move from idle breadboard tinkering into a "manufactured product".
I built a thermometer for my son. It comprises:
The result can be seen below:
(Probably could've made the black negative wire from the switch to the circuit board a little longer)
Why a momentary action switch? I didn't trust that my young son would remember to switch it off after quickly checking the temperature - so you need to hold the button down to check the temperature. So far I've never had to replace the 9V battery!
The LED display alternates between temperature and humidity. As I live in Sydney and the display is limited to two digits, there is no expectation that negative temperatures are needed. Actually, checking the code I wrote, it seems that I don't bother checking the temperature result at all - I think I assumed that the temperature returned by the DHT22 will always be above freezing point (0 Celsius)! Maybe I need to do some cold weather testing, or at least add some sanity checking! Anyway, it's safe for Sydney usage at least.
The code is here.
Here's a short video of it in action.
I built a thermometer for my son. It comprises:
- an Arduino Micro,
- a DHT22 temperature & humidity sensor (labelled "AM2302"),
- a two-digit, seven-segment LED display (labelled "CA15621BS", common anode),
- a 10kΩ resistor for the DHT22,
- seven 680Ω resistors for the LED display,
- a SPST temporary action pushbutton,
- a 9V battery,
- and an iPod touch case
The result can be seen below:
(Probably could've made the black negative wire from the switch to the circuit board a little longer)
Why a momentary action switch? I didn't trust that my young son would remember to switch it off after quickly checking the temperature - so you need to hold the button down to check the temperature. So far I've never had to replace the 9V battery!
The LED display alternates between temperature and humidity. As I live in Sydney and the display is limited to two digits, there is no expectation that negative temperatures are needed. Actually, checking the code I wrote, it seems that I don't bother checking the temperature result at all - I think I assumed that the temperature returned by the DHT22 will always be above freezing point (0 Celsius)! Maybe I need to do some cold weather testing, or at least add some sanity checking! Anyway, it's safe for Sydney usage at least.
The code is here.
Here's a short video of it in action.