How I can connect more than 10 sensors to Arduino Uno R3? I calculated it and I can connect just 4 fire flame sensors (sensors which can find a fire (a candle, for example)) and maybe 1 ultrasonic sensor. I need more for my project. I need an IR Sensor, a fire flame sensor on every side, and 1 ultrasonic sensor in front. Additionally, I need to connect 2 DC motors, 1 fan, and 1 servo-motor for ultrasonic sensor. How can I solve this? I must buy Arduino Mega?