Utilities for mobile homes, boats etc.


Senior Member
This project began as a device to display how much hot water is in the calorifier of a yacht with auxiliary engine. (The calorifier is a 60 litre tank of fresh water that is heated by the engine cooling water for washing etc.) The temperature is detected at different levels in the tank using 5 DS18B20 sensors to show how much hot water is available. Experience in use has shown that 3 sensors would give sufficient indication.
The DS18B20s are monitored by a 14M2 which uses serial communication to a 8x2 OLED which uses a modified AXE131. In my installation, the 14M2 is connected to the display by 5 metres of 3 core cable (5V, 0V and serial data at 2400 baud). The program is Cali 2.bas, attached.

Since the display is in the boat's galley, I thought it would be useful to be add a kitchen timer. This needed a significant modification of the AXE 131 program and addition of push buttons to set the time, a sounder and LED to show time up and a circuit to latch the power on with auto switch off after the timer has timed out or after 40 seconds of temperature display.
There are now 2 push buttons to switch on either the temperature display or timer function, flagged by a second pole of its push button pulling C.0 high.
The modified AXE131 is attached.



Senior Member
hi cpedw,
Nice project! Good to see other projects related to boating (there's a small subset of Picaxe users on this site who are into that stuff).
Could use a similar setup to cool solar panels & repurpose the heat. There's a lot of energy on the water to play with (wind, solar, temperature extremes, etc.).