3819 datasheet(99/218 Pages) RENESAS

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2. APPLICATION

MITSUBISHI MICROCOMPUTER

3819 Group

2.2 Timer

3819 Group USER’S MANUAL

Control procedure :

Figure 2.2.21 shows a control procedure.

Fig. 2.2.21 Control procedure [Measurement of frequency]

All interrupts : Disabled

Select the input pulse from the CNTR 1

pin as the Timer 4 count source.

Timer 1 interrupt : Enabled

Set the division ratio so that the Timer

1 interrupt occurs every 244

µs.

Start a timer counting.

Interrupts : Enabled

Set so that the processing Synchro-

nizing signal judgment is performed

every time eight Timer 1 interrupts

occur.

When the count value is 256 or more,

the processing is performed as out of

range.

Read the count value.

Store the count value in the accumu-

lator (A).

Initialize the count value.

Set the Timer 4 interrupt request bit to

“0”.

000000012

001000002

64 – 1

RESET

Initialization

SEI

T12M

T34M

ICON1

ICON2

T12M

CLI

(Address:28 16)

(Address:29 16)

(Address:3E16), bit6

(Address:3F 16), bit7

(Address:20 16)

(Address:28 16), bit0

(A)

T4 (Address:23 16)

IREQ2

(Address:23 16)

(Address:3D16), bit1

256 – 1

Timer 1 interrupt processing routine

FSync

Processing for a result of judgment

RTI

IREQ2 (Address:3D 16), bit1?

214

(A)

228?

Compare the count value read with the

reference value.

Store the comparison result in flag FSync.

Out of range

In range

1/8

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