This program controls a railroad crossing. This sample is using Jacdac modules to extend the micro:bit with programmable LEDs, servo and other sensors/actuators.

The servo uses a servo motor move to move an physical arm. The servo arm orientation is mapped to the wall clock hours: 0 (or 12) is on rotated 90 degree from the resting position to the left, 6 is rotated 90 degree right from the rest position. There is also a secret animation mode when you press the micro:bit logo button.

• when press button A, do servo set arm to 1 o’clock.

• when press button B, do servo set arm to 5 o’clock.

The LED uses a programmable LED ring module to display blue and red colors.

• when press button A, do LED set all color to red, black and repeat.

• when press button B, do LED set all color to blue, black and repeat.

• when press button B, do LED show rainbow animation.