Generic Calculator Shield for Arduino Photo-journal

[MarkHaysHarris777]

Greetings, I decided to handle the LCD back-light problem before continuing. Connected directly to the 5v supply the back-light draws 100 mA (dissipates 500 mW). So, I placed a 2N4401 switching transistor in-line with the back-light; driving it with pwm (pulse width modulation) on pin 10. I set the analogWrite(10, 120) so that the back-light is operating at 18 mA.



This has really killed two birds with one stone, as it were, because one of the generic calculator functions (as well as contrast) should be to set the display back-light (on|off) with dimmer option.

Cheers,
marcus