HMS81020TL datasheet(39/77 Pages) HYNIX

39 / 77 page

HMS81004E/08E/16E/24E/32E

JUNE 2001 Ver 1.00

11. BASIC INTERVAL TIMER

The HMS81004E/08E/16E/24E/32E has one 8-bit Basic

Interval Timer that is free-run and can not stop. Block dia-

gram is shown in Figure 11-1 .

The Basic Interval Timer generates the time base for

Standby release time, watchdog timer counting, and etc. It

also provides a Basic interval timer interrupt (IFBIT). As

the count overflow from FFH to 00H, this overflow causes

the interrupt to be generated.

-8bit binary up-counter

-Use the bit output of prescaler as input to secure the oscil-

lation stabilization time after power-on

-Secures the oscillation stabilization time in standby mode

(stop mode) release

-Contents of B.I.T can be read

-Provides the clock for watch dog timer

The Basic Interval Timer is controlled by the clock control

of CKCTLR is set to “1”, B.I.T is cleared, and then, after

one machine cycle, BTCL becomes “0”, and B.I.T starts

counting. BTCL is set to ``0`` in reset state.

The input clock of B.I.T can be selected from the prescaler

within a range of 2us to 256us by clock input selection bits

(BTS2~BTS0). (at fex = 4MHz). In reset state, or power

on reset, BTS2=“1”, BTS1= “1”, BTS0= “1” to secure the

longest oscillation stabilization time. B.I.T can generate

the wide range of basic interval time interrupt request (IF-

BIT) by selecting prescaler output.

By reading of the Basic Interval Timer Register (BITR),

we can read counter value of B.I.T. Because B.I.T can be

cleared or read, the spending time up to maximum 65.5ms

can be available. B.I.T is read-only register. If B.I.T reg-

ister is written, then CKCTLR register with same address

is written.

Figure 11-1 Block diagram of Basic Interval Timer

MUX

Basic Interval Timer Interrupt

Select Input clock 3

Basic Interval Timer

source

clock

8-bit up-counter

BTS[2:0]

BTCL

÷8

÷1024

÷512

÷256

÷128

÷64

÷32

÷16

To Watchdog timer (WDTR)

CKCTLR

clear

overflow

Internal bus line

clock control register

[0C7H]

IFBIT

Read

BITR

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