MC68HC05L28 Datasheet, PDF (57/156 Pages) Motorola, Inc – Flexible general-purpose microcomputer

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16-BIT PROGRAMMABLE TIMER
The MC68HC05L28 has a 16-bit programmable timer. This timer consists of a 16-bit read-only
free-running counter, with a fixed divide-by-four prescaler, plus input capture/output compare
circuitry.
Selected input edges cause the current counter value to be latched into a 16-bit input capture
register so that software can later read this value to determine when the edge occurred. When the
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free running counter value matches the value in the output compare registers, the programmed
pin action takes place.
See Figure 6-1 for a block diagram of the timer.
As the timer has a 16-bit architecture, each segment is represented by two 8-bit registers. These
registers contain the high and low byte of that functional segment. Accessing the low byte of a
specific timer function allows full control of that function, while accessing the high byte inhibits that
specific timer function until the low byte is also accessed.
Note:
The I-bit in the CCR should be set, while manipulating both the high and low byte register
of a specific timer function, to ensure that an interrupt does not occur.
MC68HC05L28
16-BIT PROGRAMMABLE TIMER
TPG
MOTOROLA
6-1