SLAS191A datasheet(73/86 Pages) TI

73 / 86 page

5–7

In Figure 5–3, the endless loop at the end of the program can be interrupted by pressing <ESC> in the

HyperTerminal. If no special treatment of <ESC> is required in the software UART, bit 0 in RAM location 200h

must be cleared. This bit is the ESC-active-flag and allows itself to return back to the Hyperterminal when

pressing the ESC key.

Conditions for implementation:

•

Correct setting of the P0.1 interrupt vector in the user interrupt vector table

•

The first statement of the user interrupt handler is an absolute branch to the INT_RXTX interrupt

service routine.

•

GIE is enabled.

•

The halfduplex software UART is set up to receive.

NOTE: Clear the Bit Pattern AA55h

Do not try to load a program while the bit pattern AA55h is stored at address 3DEh on

the MSP430x32x, or 5DEh on the MSP430x33x. To load a new program, clear the bit

pattern AA55h at address 3DEh on the MSP430x32x, or 5DEh on the MSP430x33x, or

switch off the STK/EVK for a short time to clear the RAM.

5.5

Transmitting a String

The first step to transmit a string is to move the bit pattern AA55h to memory location 3DEh on the

MSP430x32x, or 5DEh on the MSP430x33x. The address of the string must be stored in register R11.

The following program transmits the TEST String:

WDTCTL

.equ 0120h

WDTHold

.equ 80h

WDT_wrkey

.equ 05a00h

TXCHAR

.equ 0FFD2h

TXTABLE

.equ 0FFD4h

PREPRX

.equ 0FFD6h

PREPTX

.equ 0FFD8h

INT_RXTX

.equ 0FFDAh

TXDATA

.equ 020Eh

RXBUF

.equ 0210h

.data 0300h

STRING:

.string

“TEST”

.byte

.text

0240h

RESET:

MOV

#03DEh,SP

; #05DEh on the MSP430X33x

MOV

#(WDTHold+WDT_wrkey),&WDTCTL ; stop Watchdog Timer

EINT

; enable interrupt

TX:

MOV

#0AA55h,&03DEh

; prepare software UART for the

; use in user application

(&05DEh on the MSP430X33x

MOV

#STRING,R11

; Test: TX_table

;

BIC

#01h,&200h

; use only if no special

; treatment of ESC is wanted

CALL

&TXTABLE

; call transmit sub-routine in

; monitor

(05DEh on the MSP430X33x

CALL

&PREPRX

; prepare software UART for

SLAS191A Datasheet(PDF) 73 Page - Texas Instruments

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