microprocessor problems

EET 3264 - Fall 2014 - Exam I

1) Suppose the keypad is connected to PORTB as shown below. For each of the keys, determine

the pattern that would be used in the keypad scanning routine. (16 patterns needed.)

PIC

RB7

RB6

RB5

RB4

RB3

RB2

RB1

RB0

1 2 3 A

4 5 6 B

7 8 9 C

* 0 # D

Row 2

Col 2

Row 4

Row 3

Col 1

Row 1

Col 3

Col 4

C1 C2 C3 C4

R1

R2

R3

R4

2) For the PWM waveform shown in the following scope image, determine the frequency, the

duty cycle, and the average voltage. Show your work.

3) Determine the values that should be loaded into each register listed below to get a 1000Hz

PWM signal with a duty cycle of 40%. Assume that the oscillator frequency is 16MHz.

CCP2CON:

CCPR2L:

PR4:

T4CON:

CCPTMRS0:

4) Suppose the UART has been initialized with the values given below. If the oscillator

frequency is 12MHz, what is the Baud rate of the UART?

TXSTA = 0x20 RCSTA = 0x80

BAUDCON = 0x08

SPBRGL = 0x37

SPBRGH = 0x01

5) Sketch the timing diagram for an asynchronous serial transmission of the value 0x74.

6) Write a C-language function to set up the DAC in the PIC16F1936 as follows. Do not use

macros.

Pos. Ref. is Vdd

Neg. Ref. is input on RA2

DAC voltage is 3/4 full-scale

DAC output pin not enabled