HC705E5GRSSLASHD datasheet(59/148 Pages) NXP

59 / 148 page

Timer

Timer Counter Register

MC68HC705E5 — Rev. 1.0

General Release Specification

Timer

8.4 Timer Counter Register

The timer counter register (TCR) is a read-only register which contains

the current value of the 8-bit ripple counter at the beginning of the timer

chain. This counter is clocked at fop divided by four and can be used for

various functions including a software input capture. Extended time

periods can be attained using the TOF function to increment a temporary

RAM storage location, thereby simulating a 16-bit (or more) counter.

The power-on cycle clears the entire counter chain and begins clocking

the counter. After 4064 cycles, the power-on reset circuit is released,

which again clears the counter chain and allows the device to come out

of reset. At this point, if RESET is not asserted, the timer will start

counting up from zero and normal device operation will begin. When

RESET is asserted any time during operation other than POR, the

counter chain will be cleared.

Address:

$0009

Bit 7

654321

Bit 0

Read:

Write:

Reset:

00000011

= Unimplemented

Figure 8-3. Timer Counter Register (TCR)

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

HC705E5GRS/D Fiches technique(PDF) 59 Page - NXP Semiconductors