Switch Loop Wiring Diagram Two Switches - This provides a direct signal from the MegaSquirt ® EFI controller to the PWM idle valve. Note that the transistor on the V3 main board is NOT sufficient to drive a. This shopping feature will continue to load items. In order to navigate out of this carousel please use your heading shortcut key to navigate to the next or previous heading.. Other Arduino Boards. Arduino Nano, Arduino Pro Mini, Arduino Mega, Arduino Due, Arduino Leonardo. Overview. Arduino Uno is a microcontroller board based on 8-bit ATmega328P microcontroller. Along with ATmega328P, it consists other components such as crystal oscillator, serial communication, voltage regulator, etc. to support the microcontroller..