1) Count the number of 1s on ports A and B and output that number on port C.
2) A car has a fuel-level sensor that sets PA3..PA0 to a value between 0 (empty) and 15 (full). A series of LEDs connected to PC5..PC0 should light to graphically indicate the fuel level. If the fuel level is 1 or 2, PC5 lights. If the level is 3 or 4, PC5 and PC4 light. Level 5-6 lights PC5..PC3. 7-9 lights PC5..PC2. 10-12 lights PC5..PC1. 13-15 lights PC5..PC0. Also, PC6 connects to a "Low fuel" icon, which should light if the level is 4 or less.
3) In addition to the above, PA4 is 1 if a key is in the ignition, PA5 is one if a driver is seated, and PA6 is 1 if the driver's seatbelt is fastened. PC7 should light a "Fasten seatbelt" icon if a key is in the ignition, the driver is seated, but the belt is not fastened.
4) **(Challenge):** Read an 8-bit value on PA7..PA0 and write that value on PB3..PB0PC7..PC4. That is to say, take the upper nibble of PINA and map it to the lower nibble of PORTB, likewise take the lower nibble of PINA and map it to the upper nibble of PORTC (PA7 - PB3, PA6 - PB2, … PA1 - PC5, PA0 - PC4).
5) **(Challenge):** A car's passenger-seat weight sensor outputs a 9-bit value (ranging from 0 to 511) and connects to input PD7..PD0PB0 on the microcontroller. If the weight is equal to or above 70 pounds, the airbag should be enabled by setting PB1 to 1. If the weight is above 5 but below 70, the airbag should be disabled and an "Airbag disabled" icon should light by setting PB2 to 1. (Neither B1 nor B2 should be set if the weight is 5 or less, as there is no passenger)
