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¡ Semiconductor

MSM82C53-2RS/GS/JS

• Mode 4 (software trigger strobe)

The counter output is switched to “H” level by the mode setting. Counting is started in the

same way as described for mode 0. A single “L” pulse equivalent to one clock width is

generated at the counter output when the terminal count is reached.

This mode differs from 2 in that the “L” level output appears one clock earlier in mode 2, and

that pulses are not repeated in mode 4. Counting is stopped when the gate input is switched

to “L” level, and restarted from the set count value when switched back to “H” level.

• Mode 5 (hardware trigger strobe)

The counter output is switched to “H” level by the mode setting. Counting is started, and the

gate input used, in the same way as in mode 1.

The counter output is identical to the mode 4 output.

The various roles of the gate input signals in the above modes are summarized in the following

table.

0

1

"H" Level

"L" Level Falling Edge

Rising Edge

Mode

Gate

Counting not possible

Counting possible

(1)

(2)

Start of counting

Retriggering

2

(1)

(2)

Counting not possible

Counter output forced to "H" level

Start of counting

Counting possible

3

(1)

(2)

Counting not possible

Counter output forced to "H" level

Start of counting

Counting possible

4

Counting not possible

Counting possible

5

(1)

(2)

Start of counting

Retriggering