Freescale Semiconductor, Inc.
Inte rrup ts
4.8 Prog ra m m a b le Tim e r Inte rrup ts
The 16-bit programmable timer can generate an interrupt whenever the
following events occur:
• Input capture
• Output compare
• Timer counter overflow
Setting the I bit in the condition code register disables timer interrupts.
The controls for these interrupts are in the timer control register (TCR)
located at $0012 and in the status bits in the timer status register (TSR)
located at $0013.
4.8.1 Inp ut Ca p ture Inte rrup t
An input capture interrupt occurs if the input capture flag (ICF) becomes
set while the input capture interrupt enable bit (ICIE) is also set. The ICF
flag bit is in the TSR, and the ICIE enable bit is located in the TCR. The
ICF flag bit is cleared by a read of the TSR with the ICF flag bit set, and
then followed by a read of the LSB of the input capture register (ICRL)
or by reset. The ICIE enable bit is unaffected by reset.
4.8.2 Outp ut Com p a re Inte rrup t
An output compare interrupt occurs if the output compare flag (OCF)
becomes set while the output compare interrupt enable bit (OCIE) is also
set. The OCF flag bit is in the TSR and the OCIE enable bit is in the TCR.
The OCF flag bit is cleared by a read of the TSR with the OCF flag bit
set, and then followed by an access to the LSB of the output compare
register (OCRL) or by reset. The OCIE enable bit is unaffected by reset.
General Release Specification
MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0
Interrupts
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