2. You are to interface a keyboard to the microprocessor. The keyboard generates a 1-bit control...

  

Transcribed Image Text:

2. You are to interface a keyboard to the microprocessor. The keyboard generates a 1-bit control signal, READY, which goes high when a key is pressed and then goes low when the ASCII character of the key is read by the microprocessor through the port at the address $6000. The control signal READY is connected to the LSB of the port at the address $6001. (a) Design the interface using a decoder 74LS139, random gates, and two buffers. Each buffer has 8-bit input and output, and an active-high enable, E. Provide a complete circuit diagram with all address, data and control bits clearly labeled. All address bits should be decoded. (b) Write a program for this interface, which reads in 8 new characters and stores them in the array KEYS, one character at a time, using the HCS12 instructions. 2. You are to interface a keyboard to the microprocessor. The keyboard generates a 1-bit control signal, READY, which goes high when a key is pressed and then goes low when the ASCII character of the key is read by the microprocessor through the port at the address $6000. The control signal READY is connected to the LSB of the port at the address $6001. (a) Design the interface using a decoder 74LS139, random gates, and two buffers. Each buffer has 8-bit input and output, and an active-high enable, E. Provide a complete circuit diagram with all address, data and control bits clearly labeled. All address bits should be decoded. (b) Write a program for this interface, which reads in 8 new characters and stores them in the array KEYS, one character at a time, using the HCS12 instructions.

Answer rating: 100% (QA)

2 Keyboard Interface and Program a Circuit Diagram Heres the circuit diagram for interfacing the key... View the full answer