Motorola M68CPU32BUG Manuale Utente Scaricare il pdf (Pagina 20)

MOVE.W #$0001,PEDR * make E= 0 (info strobed to Display)

* bit 3 2 1 0

* 0 0 0 1

* E R/W RS note RS = 1 for

* writing data into LCD

BSR DELAY

PRELAB

The following is to be performed prior to attending the scheduled lab session:

• Read the contents of this lab in its entirety.

• Read and understand the LCD datasheet given in Appendix 5

• Write the required MC68000 programs.

Part 1: Requirement

Write an MC68000 program which will turn on and off a light emitting diode. The LED is

to be connected to bit 0 of Port F and ground. Refer to Figure 1 for the details of con-

necting the LED to the CMM 332 board. The LED is to be ON for approximately 0.5 sec-

onds and OFF for 0.5 seconds. Use a delay subroutine to control these ON and OFF

times. The main program is to initialize the ports and then repeatedly turn ON and OFF

bit 0 of Port F. The printed circuit board containing the main CMM 332 board and the

LCD display contains a 14 pin header which provides access to all 8 bits of Port F and

the three low-order bits of Port E. It is necessary to turn on the power switch which pro-

vides power to the LCD module in order to be able to access the pins of the header. The

pseudocode is as follows:

conﬁgure Port F as parallel output

loop: write a logic ‘1’ to port F, bit 0

delay for 0.5 seconds

write a logic ‘0’ to port F, bit 0

delay for 0.5 seconds

branch to loop

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Motorola M68CPU32BUG Manuale Utente Pagina 20