SLAS191A Datasheet, PDF (70/86 Pages) Texas Instruments – Starter Kit Evaluation Kit Manual

5.3 Special Treatment of <ESC> in the Software UART
The software UART treats a received ESC character in two different ways:
• The software UART receives the ESC character and stores it at address 210h. The condition,
therefore, is that bit 0 in memory location 200h is reset.
• The software UART receives the ESC and returns back to the Hyperterminal. The condition is
that bit 0 in memory location 200h be set.
End of ROM-Monitor
Interrupt Service Routine
Contents of
Memory Location
yes
3DEh is AA55h for
no
MSP430X32x
(or 5DEh is AA55h
for MSP430X33x)
no
Bit 0 in Memory
yes
Location 200h Set ?
no
Received Character
is <ESC>
Normal Return Out of
INT_RXTX
Interrupt
Service
yes
The Return From Interrupt
is By-Passed
Into ROM-
Monitor
Figure 5–2. Special Treatment of ESC
BIC #01h,&200h ; reset bit 0, because no special treatment of <ESC> is
; wanted
BIS #01h,&200h ; reset bit 0, because special treatment of <ESC> is
; wanted
NOTE: Memory Location 200h
Only bit 0 in memory location 200h may be modified. A modification of the higher bits may result
in an unpredictable behavior of the terminal program.
5–4