1) Garage open at night-- A garage door sensor connects to PA0 (1 means door open), and a light sensor connects to PA1 (1 means light is sensed). Write a program that illuminates an LED connected to PB0 (1 means illuminate) if the garage door is open at night.
2) Port A's pins 3 to 0, each connect to a parking space sensor, 1 meaning a car is parked in the space, of a four-space parking lot. Write a program that outputs in binary on port C the number of available spaces (Hint: declare a variable "unsigned char cntavail;" you can assign a number to a port as follows:
PORTC = cntavail;).
3) Extend the previous program to still write the available spaces number, but only to PC3..PC0, and to set PC7 to 1 if the lot is full.
4) **(Challenge)** An amusement park kid ride cart has three seats, with 8-bit weight sensors connected to ports A, B, and C (measuring from 0-255 kilograms). Set PD0 to 1 if the cart's total passenger weight exceeds the maximum of 140 kg. Also, the cart must be balanced: Set port PD1 to 1 if the difference between A and C exceeds 80 kg. The remaining 6 bits on D should display an approximation of the total combined weight, accurate within 3 kg. (Interesting note: Disneyland recently redid their "It's a Small World" ride because the average passenger weight has increased over the years, causing more boats to get stuck on the bottom).
