COE 538 Exam M/C

When a microcontroller completes execution of an interrupt service routine, it resumes the main program execution from the address saved in:

Stack

Where does the 9S12 processor start to execute the program when power is turned on?

The program starting address is fetched from a fixed memory location

How many bytes are reserved by the following Assembler directive: dc.b $16 ?

1 byte

The following interface allows the 9S12 to communicate asynchronously with peripheral devices

SCI

After execution of the following instruction: movb #$FC, $1020 , the Carry bit will be

Not affected

A microcontroller normally has the following devices on-chip

RAM, ROM, I/O units

The capacity of the memory chip with the 11-bit address bus and 8-bit data bus is:

2KB

What register is used to keep track of the address of the next instruction to be executed

Program Counter

List the instruction used to enable and disable all interrupts in the HCS12.

Interrupt enable instruction: _____

Interrupt disable instruction: ———

CLI - clear interior mask, SEI - set interrupt mask

For a CPU of 16 address line and 8 data lines, the address space available for the memory, ports, and peripheral devices is equal to:

Address area = 2^20 = 2^10 × 2^16 = 64K locations

For a CPU bus of 16 address lines and 8 data lines, how many E-clocks are required to store a 16-bit result into memory, if each byte reading/writing cycle requires 4 E-clocks:

Number of clock cycles = 16/8 = 2 read/write cycles, 2 × 4 = 8 E-clocks

What makes a microcontroller different from a microprocessor?

Embedded peripheral devices (ports, timers, ADC, etc.)

For a CPU bus of 20 address lines and 8 data lines, the address space available for the memory, ports, and peripheral devices is equal to:

Address area = 2^20 = 2^10 × 2^10 = 1024K

For a CPU by of 20 address lines and 8 data lines, how many E-clocks are necessary for the CPU to write a 32-bit result into memory if each byte reading/writing cycle requires 4 E-clocks:

Number of clock cycles = 32/8 = 4 read/write cycles, 4 × 4 = 16 E-clocks

Convert 4K to decimal representation

4K = 4 × 2^10 = 4 × 1024 = 4096

How many locations are contained in the memory space $2000-$29FF?

10 × 16 × 16 = 2560

What HCS12 instruction is used to disable all maskable interrupts?

SEI

What does MISO stand for

Master-Input-Slave-Output

Instruction to allocate 10 bytes for local variables in the stack

LEAS -10, SP

What is the major difference between the SCI and SPI serial data transfer protocols?

The SCI is an asynchronous transfer protocol; whereas the SPI is a synchronous one (includes the clock signal)