CENG 4313 Microcontroller Interfacing
Study Questions for Ch. 8
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What are the three components to microcomputer interfacing?
What is meant by the mechanical design?
What are analog and digital electronics used for?
What is meant by voltage translation and why is it important?
What is the group of low level functions (software) that transforms the electrical
devices into objects that perform the desired tasks called?
6. The 9S12 is built with what type of logic?
7. What is the common name that the SCI uses?
8. What does SCI stand for?
9. How does Valvano define the baud rate?
10. The baud rate control register is used for what purpose?
11. How many data bits are in a frame when the mode bit M is set to 0? What about
setting M to 1? (See figure 8.1 for an example.)
12. How is the start bit used?
13. According to figure 8.1 a frame includes what bits?
14. The RS232 standard used what kind of connector?
15. The EIA 574 standard uses RS232 voltages but what kind of connector?
16. What three signals can be used to implement a simple bidirectional serial
channel?
17. What is defined as a DTE? A DCE?
18. A Maxim converter chip (MAX 232A) is used to generate what voltages.
19. What voltage (+ 12 or -12v) is considered a digital low on the cable to the DB9
connector? A digital high?
20. What is the designation of PIN 2 and PIN 3 of the DB9 connector in Figure 8.2?
21. For asynchronous transmission, the software of the 9S12 C32 writes data to what
register?
22. What is the proper sequence for writing 9-bit data and using the T8 bit of the
SCIDRH register?
23. Why do we initialize the TE control bit to 1?
24. When receiving, in what register is the data placed? If we are operating in 9bit mode where is the extra bit located?
25. What bit is set to enable the receiver?
26. Which of the status bits is set when new input data is available?
27. What is meant by an Overrun (OR) Flag? How is it set?
28. When is the Noise Flag (NF) set?
29. When is the Framing Error (FE) set?
30. On the 9S12C32 the one Port that is used is which port and which bits are used in
that port?
31. Which bits of the SCIBD register determine the baud rate for the SCI port?
32. What equation is used to calculate the SCI Baud rate?
33. What are the three public functions discussed in Example 8.1
34. What processor is assumed in Programs 8.1 and 8.2? How do you know?
35. The SCI works well for speeds up to what value?
36. What was one of the first protocols to replace the SCI for higher speeds?
37. What is the typical use of the SPI?
38. The Freescale SPI has four control lines (slave select, SClk, master out slave or
MOSI, and mater in slave out or MISO.) –explain the function of these four lines.
39. Draw and explain a figure like Figure 8.7 for the 9S12C32.
40. What is the function of the MAX550A? Why is this needed in the 9S12 series of
microcontrollers?
41. What are the 4 basic interfacing issues with any SPI interface as discussed by
Valvano on page 299 in Example 8.2?
42. What is meant by a scanned interface? What is the example device used in section
8.4
43 What standard chip is used to interface an LCD?
44. Why are relays, solenoids and DC motors grouped together?
45. What does the microcontroller do to deliver variable power?
46. How is the duty cycle defined for PWM?
47. What is the equation for delivered power as related to the duty cycle of PWM?
48. Motors can be evaluated in terms of what three things?
49. What type of motor do we use when we want to control the rotational position rather
than the rotational speed?
50. What applications do we use for stepper motors?