Motorola Axiom CMD11E1 Guía de usuario descargar pdf (Pagina 48)

48 CHAPTER 3. FUNCTIONS AND BIT MANIPULATIONS

2. Connect the input circuit as shown in ﬁgure 3.2.

3.10.2 Controlling the LED

Use memory modify, MM $1000, command to modify PORTA. Change the value

in the location to 00, 10, 20, and 30. (Note: When you communicate directly

with the HC11 using BUFFALO commands, you do not type the $.) After each

change, look at the state of the light emitting diodes and write down what you

see. Provide a brief explanation of what you see.

Using the methods you learnt in earlier labs, write a program that will read

the keyboard and depending on what the user types, perform the following:

Key Action

Q or q Turn on the LEFT led. The state of other led should not change.

Z or Z Turn oﬀ the LEFT led. The state of other led should not change.

E or e Turn on the RIGHT led. The state of other led should not change.

C or c Turn oﬀ the RIGHT led. The state of other led should not change.

3.10.3 Reading an external switch

Use memory dump to see the contents of $1000. Close the input switch and dump

the contents of location $1000. Repeat the experiment with the switch open.

Write down what you see and provide a brief explanation of your observation.

Write a program that will, in an inﬁnite loop, print either CLOSED or OPEN,

depending on the state of the switch. The program should continually monitor

the state of the switch, and print CLOSED is the switch is closed. Or else it should

print OPEN.

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Motorola Axiom CMD11E1 Guía de usuario Pagina 48