Start Timer At T=0 (.Tm_Str0) - Motorola M68CPU32BUG User Manual

.TM_STR0
5.2.21 Start Timer at T=0
SYSCALL
TRAP CODE: $0041
Use this routine to reset the timer to 0 and start it. The user can select values for the MCU
periodic interrupt timer (periodic interrupt timing register (PICR) and periodic interrupt control
register (PITR)), or use the default values. The default values set the interrupt frequency to 125
milliseconds and use level 6, vector 66. See Appendix C of this manual and the MC68332 User's
Manual, MC68332UM/AD, concerning the Periodic Interrupt Timer for more details.
Entry Conditions:
SP ==>
Exit Conditions Different From Entry:
Parameters are removed from the stack, the timer is started, and the interrupt pulse
counter is cleared. If the user's interrupt level, as defined in the status register
(SR), disables the timer interrupts, the SR interrupt mask bits are changed to allow
timer interrupts.
If the value of PICR is not equal to the power-up default value, $000F, the old
vector number is restored to the default CPU32Bug value.
EXAMPLES
SYSCALL .TM_STR0
MOVE.L #0,-(A7)
SYSCALL .TM_STR0
M68CPU32BUG/D REV 1
Start Timer at T=0
.TM_STR0
Timer control value (for PICR) <word>
Timer period value (for PITR) <word>
Reset the timer to zero and start it with the default values.
5-25
SYSTEM CALLS
.TM_STR0