When using an arduino as a sink it is important that the scource voltage is not above the supply to the arduino either 5 V or 3.3.
You need to use an external transistor or you risk destroying you arduino.
You need to post a circuit diagram.
When using an arduino as a sink it is important that the scource voltage is not above the supply to the arduino either 5 V or 3.3.
You need to use an external transistor or you risk destroying you arduino.
You need to post a circuit diagram.