SPMCK16Z4MPV20 datasheet(474/500 Pages) FREESCALE

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INITIALIZATION AND PROGRAMMING EXAMPLES

M68HC16 Z SERIES

E-22

USER’S MANUAL

LDAB

SCCNT,Z

JSR

HEXTOASC

;convert hex number to ASCII and print

LINE_FD:

;output a linefeed

LDAB

#$0A

;load ASCII number for line feed

JSR

SEND_CH

;send character to terminal

CARRIAGE:

;output a carriage return

LDAB

#$0D

;ASCII number for carriage return

JSR

SEND_CH

;send character to terminal

RTS

;done with display routine

*****

Hexadecimal to ASCII conversion

*****

HEXTOASC:

;the following code takes a number or

;character stored in register D, assumes

;it's in its hexadecimal form and converts

;it to an ASCII equivalent. It also sends

;that character to the screen.

STD

TEMP,Z

;store the hex number temporarily into “TEMP”

JSR

PRTMSB

LDD

TEMP,Z

;reload value of hex number into D register

ANDB

#$0F

;get rid of upper 4 bits in hex number

BRA

PRTLSB

PRTMSB: LSRB

;shift high 4 bits down to low 4 bits position

LSRB

PRTLSB:

;the actual conversion process:

ADDB

#$30

;add $30 to the hex number

CMPB

#$39

;check for digithood

BLS

NOTAF

;go print now if it's a digit 0-9

ADDB

#$07

;it's a letter A-F, so add $07 before printing

NOTAF:

JSR

SEND_CH

;send the character to the SCI

RTS

;done with hex to ascii conversion

*****

Autovector Routine

*****

AUTOV:

;when IRQ6 is low, this autovector routine starts

LDAB #$55

;These four lines reset the watchdog and keep it

STAB SWSR

;from causing a system reset by writing to the SWSR

LDAB #$AA

;By writing a #$55 and a #$AA to the SWSR before

;the end

STAB SWSR

;of every time-out period, the watchdog will be

reset.

LDX

#AUTOV_STRING

JSR

SEND_STRING

RTI

;return to the main loop

*****

Other exception/interrupts

*****

BDM:

BGND

;all other exception vectors point here

;and put the user into background mode

Freescale Semiconductor, Inc.

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Go to: www.freescale.com

SPMCK16Z4MPV20 Datasheet(PDF) 474 Page - Freescale Semiconductor, Inc

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