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Step 3: SOAP - Schematic

Picture of SOAP - Schematic

The circuit of SOAP is shown above.

Each LDR is connected to 0V and to +5V via a dropper resistor. The connection point between the LDR and the resistor is connected to an input on the UNO R3. The values of the resistors were determined by experiment so that an illuminated LDR results in a voltage below 3V at the UNO input, while an LDR in darkness gives rise to a voltage of more than 3V.

14 inputs to the UNO R3 were required. This was achieved by using digital inputs D2 to D9 and analogue inputs A0 to A5. The analogue inputs are configured to operate as digital inputs.

The audio output is produced by a Velleman KA02 Audio Shield.

The unit is powered by a PP9 9V battery via a latching pushbutton. The UNO R3 code runs as soon as power is applied.

The resistors and LDRs are numbered to match the wash programme numbers.

Note that all of the drawings in this Instructable are also contained in the multi-page PDF attached.