MC68HC16Z1 Datasheet, PDF (468/500 Pages) Freescale Semiconductor, Inc – M68HC16Z Series

Freescale Semiconductor, Inc.
BEQ
again
CLRA
STD
TC_LOOP:
LDAB
ANDB
BEQ
SEND_CH
SCDR
SCSR+1
#$80
TC_LOOP
;if TDR is not empty, go back to check it
;transmit one ASCII character to the screen
;test the TC bit (transfer complete)
;continue to wait until TC is set
RTS
;finish sending out one character
***** Exceptions/Interrupts *****
BDM: BGND
;exception vectors point here
;and put the user in background mode
***** The string *****
ORG
$0310
STRING DC 'I LIKE MY NEW MEMORY!!!',0A,0D,00
E.2.1.3 Example 3 - Changing Clock Frequencies
*
Description : This program demonstrates the ability of the
*
M68HC16 to change clock frequencies on the fly.
*
In this particular case, we alternate between
*
a frequency of 16.78MHz and 4.194MHz. Note
*
that because we are writing to the screen,
*
we also need to correct the BAUD rate (1200)
*
each time we change the frequency. Make sure
*
that your terminal has been set up to receive
*
at 1200 baud. An oscilloscope may be connected
*
to the CLKOUT pin on the EVB to observe the
*
frequency change.
***************************************************************************
INCLUDE
INCLUDE
INCLUDE
'EQUATES.ASM' ;table of EQUates for common registers
'ORG00000.ASM' ;initialize reset vectors
'ORG00008.ASM' ;initialize interrupt vectors
ORG
$0200
;start program after the exception
;vector table
***** Initialize *****
INIT:
INCLUDE
COP
INCLUDE
'INITSYS.ASM' ;initially set EK=F, XK=0, YK=0, ZK=0
;set sys clock at 16.78 MHz, disable
'INITRAM.ASM' ;turn on internal 1K SRAM at $10000
;set stack in bank 1 (SK=1, SP=03FE)
LDD
#$000C
E-16
INITIALIZATION AND PROGRAMMING EXAMPLES
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M68HC16 Z SERIES
USER’S MANUAL