An automatic flushing mechanism includes an electronic control box containing a motor and an intermittent motion gear coupled to a rotation shaft of the motor. The intermittent motion gear is configured to rotate when the motor is operated. The intermittent motion gear includes a toothed portion including a plurality of gear teeth. The automatic flushing mechanism includes an intermittent motion pendulum rod including a first end pivotally attached to the electronic control box via a rotation shaft, a second end coupled to a flush valve, and a curved rack including a plurality of rack teeth which mesh with the gear teeth of the intermittent motion gear. Rotation of the intermittent motion gear causes the curved rack to be lifted upward, thereby rotating the intermittent motion pendulum rod about the rotation shaft and lifting the flush valve.