XC912BC32CFU8 Motorola Semiconductor Products, XC912BC32CFU8 Datasheet - Page 224

• Manufacturer Part Number: XC912BC32CFU8
• Description: M68HC12B Family Data Sheet
• Manufacturer: Motorola Semiconductor Products

Serial Interface
14.5 Serial Character Transmission using the SCI
14.5.1 Equipment
14.5.2 Code Listing
INCLUDE 'EQUATES.ASM'
; User Variables
; Bit Equates
; ----------------------------------------------------------------------
;
; ----------------------------------------------------------------------
;
MAIN:
DONE:
; ----------------------------------------------------------------------
;
; ----------------------------------------------------------------------
INIT:
;
Data Sheet
224
ORG
BSR
BSR
BRA
TPA
ORAA
TAP
MOVB
MOVB
MOVB
LDAA
STD
LDX
RTS
NOTE:
SUBROUTINE INIT:
MAIN PROGRAM
$7000
INIT
TRANS
DONE
#$10
#$34,SC1BDL
#$00,SC1CR1
#$08,SC1CR2
SC1SR1
SC1DRH
#DATA
Code is intended to use SCI1 to serially transmit characters using polling to the
LCD display on the UDLP1 board: when the transmission data register is empty a
flag will get set, which is telling us that SC1DR is ready so we can write another
byte. The transmission is performed at a baud rate of 9600. Since the SCI1 is only
being used for transmit data, the data register will not be used bidirectionally for
received data.
For this exercise, use the M68HC912B32EVB emulation board.
A comment line is deliminted by a semi-colon. If there is no code before comment,
an “;” must be placed in the first column to avoid assembly errors.
; Equates for registers
; 16K On-Board RAM, User code data area,
; start main program at $4000
; Subroutine to Initialize SCI0 registers
; Subroutine to start transmission
; Always branch to DONE, convenient for breakpoint
; Transfer CCR to A accumulator
; ORed A with #$10 to Set I bit
; Transfer A to CCR
; Set BAUD =9600, in SCI1 Baud Rate Reg.
; Initialize for 8-bit Data format,
; Loop Mode
; Set for No Ints, and Transmitter enabled(SC1CR2)
; 1st step to clear TDRE flag: Read SC1SR1
; 2nd step to clear TDRE flag: Write SC1DR register
; Use X as a pointer to DATA.
; Return from subroutine
Serial Interface
and parity disabled,(SC1CR1)
M68HC12B Family — Rev. 8.0
MOTOROLA