March 13, 2011

Standalone version for my 2-Sensors Thermometer

Since I wanted to free up my precious Digit Shield, I've realized a stand alone version of my two sensors Thermometer using a minimal realization of an Arduino board and a stand alone realization of a Digit Shield (following the official schematics).

The 7-Segments_Digits-Display salvaged from an old VCR is a Lite-On LTC-4627G, which is a common anode display as the ones used in the Digit Shield (I found its datasheet here).

Here's my new Thermometer!



A clear enclosure (from a DVD case) contains a stand alone implementation of the 4-digits 7-segments display, a minimal Arduino, two push buttons, the battery holder (2xAA batteries = 3V) and a voltage booster to get 5V stabilized DC power supply from the two AA batteries. Everything is kept in place using a thin piece of foam cut to measure to leave enough space to the various internals. The sensors bus wires with two Dallas sensors are also visible in the picture.

Near the 4-digits 7-segments display I've added one flat LED as "minus sign" to indicate negative temperatures, and another small LED to indicate an "external" temperature (see this post for details).



This is the schema I've followed to realize a stand alone implementation of the Digit Shield on a stripboard:



The code (Thermometer_7SegmentsDisplay_v03.pde) running on the ATMEGA328 is the same used here.