TMP88CS38FG datasheet(64/226 Pages) TOSHIBA

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TMP88CS38/CM38A/CP38A

2007-09-12

88CS38-64

Figure 2.5.3 Timer Mode Timing Chart

(2) External trigger timer mode

In this mode, counting up is started by an external trigger. This trigger is the edge of

the TC1 pin input. Either the rising or falling edge can be selected with TC1S. Source

clock is an internal clock. The contents of TC1DRA is compared with the contents of up

counter. If a match is found, an INTTC1 interrupt is generated, and the counter is

cleared to “0” and halted. The counter is restarted by the selected edge of the TC1 pin

input.

When METT1 (Bit6 in TC1CR) is “1”, inputting the edge to the reverse direction of

the trigger edge to start counting clears the counter, and the counter is stopped.

Inputting a constant pulse width can generate interrupts. When METT1 is “0”, the

reverse directive edge input is ignored. The TC1 pin input edge before a match

detection is also ignored.

The TC1 pin input has the noise rejection; therefore, pulses of 7/fc [s] or less are

rejected as noise. A pulse width of 13/fc [s] or more is required for edge detection in

NORMAL or IDLE mode.

Example 1: Detects rising edge in TC1 pin input and generates an interrupt 100

μs later. (at fc = 16.0 MHz, DV1CK

= 1)

LDW

(TC1DRA), 0064H

;

100

μs ÷ 24/fc = 64H

SET

(EIRL). 4

;

INTTC1 interrupt enable

(TC1CR), 00001000B

;

Selects the source clock and mode

(TC1CR), 00101000B

;

TC1 external trigger start, METT1

= 0

Example 2: Generates an interrupt, inputting “L” level pulse (Pulse width: 4 ms or more) to the TC1 pin. (at fc

= 16.0

MHz, DV1CK

= 1)

LDW

(TC1DRA), 00FAH

;

4 ms

÷ 28/fc = FAH

SET

(EIRL). 4

;

INTTC1 interrupt enable

(TC1CR), 00000100B

;

Selects the source clock and mode

(TC1CR), 01110100B

;

TC1 external trigger start, METT1

= 1

− 1

− 2

Up counter

TC1DRB

ACAP1

Capture

+ 1m + 2

(b) Auto capture

TC1DRA

INTTC1 interrupt

− 1n

+ 1

Capture

Count start

Source clock

Up counter

Source clock

− 1n 0

Match detect

Counter clear

(a) Timer mode

− 1

+ 1m + 2n − 1

+ 1

TMP88CS38FG Datasheet(PDF) 64 Page - Toshiba Semiconductor

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