mc68hc908jb8 Freescale Semiconductor, Inc, mc68hc908jb8 Datasheet - Page 114

• Manufacturer Part Number: mc68hc908jb8
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

System Integration Module (SIM)
8.8.2 Reset Status Register
Technical Data
114
;
This code works if the H register has been pushed onto the stack in the break service
routine software. This code should be executed at the end of the break service routine
software.
HIBYTE
LOBYTE
DOLO
RETURN
EQU
EQU
If not SBSW, do RTI
BRCLR
TST
BNE
DEC
DEC
PULH
RTI
This register contains seven flags that show the source of the last reset.
All flag bits are cleared automatically following a read of the register. The
register is initialized on power-up as shown with the POR bit set and all
other bits cleared. However, during a POR or any other internal reset,
the RST pin is pulled low. After the pin is released, it will be sampled 32
XCLK cycles later. If the pin is not above a V
bit in the RSR may be set in addition to whatever other bits are set.
SBSW can be read within the break state SWI routine. The user can
modify the return address on the stack by subtracting one from it.
The following code is an example of this. Writing 0 to the SBSW bit
clears it.
5
6
SBSW,BSR, RETURN
LOBYTE,SP
DOLO
HIBYTE,SP
LOBYTE,SP
System Integration Module (SIM)
MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3
;
;
; If RETURNLO is not zero,
; then just decrement low byte.
; Else deal with high byte, too.
; Point to WAIT/STOP opcode.
; Restore H register.
See if wait mode or stop mode was exited
by break.
IH
at that time, then the PIN
Freescale Semiconductor