WiFi Boat Monitor - Sensors
- Created on Monday, 27 September 2010 18:37
- Last Updated on Wednesday, 30 April 2014 22:25
- Written by Mike Holden
- Hits: 26173
Page 4 of 5
- Hatch boards in/out (as a burglar alarm)
This uses a magnetic burgler alarm switch (I used the kind that mounts in a hole like the NTE 54-629). I enable the pull-ups on the Atmel, and wire the switch so it shorts to ground. Here is a sketch:
- Engine On/Off (to calculate run time)
This uses a 12V supply that turns on with the engine. For example, the ignition key, or the supply to the electric fuel pump. To reduce the voltage from 12V to 5V, I considered a Voltage divider, but went instead with a 5V regulator. The 3 terminal part is easier to hook up, and gives a logic high voltage for a wide range of input voltages.
- Interior temperature
I used the LM335A with a 5.1K resistor. The Voltage from the circuit is 10 mV / deg K (note the drawing below is mislabeled). This one needs an analog input on the microcontroller to read it. It seems to read a little hotter than it actually is, by 5 degrees or so.
- Battery Voltage
Just a simple voltage divider. This drains the battery over time. I was too lazy to think of something better, hopefully my solar panel can keep up with the mA it draws.
More to come. A bilge water level detector would probably make sense too, but the sensors above are actually in place and working.