MC68HC05J3 View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

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MC68HC05J3

High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

Motorola => Freescale 

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16-BIT PROGRAMMABLE TIMER

The programmable timer on the MC68HC05J3 consists of a 16-bit read-only free-running counter,

with a fixed divide-by-four prescaler, plus the 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 free

running counter value matches the value in the output compare registers, the programmed pin

action takes place. Refer to Figure 6-1 for a block diagram of the timer. The input capture and

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output compare functions can only be enabled by setting bit 4 and bit 5 of the port B configuration

register as described in Section 4.4.3.

The timer has a 16-bit architecture, hence each specific functional 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; however, an access of

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.

MC68HC05J3

16-BIT PROGRAMMABLE TIMER

TPG

MOTOROLA

6-1

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