M34280E1FP View Datasheet(PDF) - MITSUBISHI ELECTRIC

Part Name

Description

Manufacturer

M34280E1FP

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTERS

MITSUBISHI ELECTRIC  

MITSUBISHI MICROCOMPUTERS

4280 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTERS

Table 4 Control registers related to timer

Timer control register V1

at reset : 0002

at RAM back-up : 0002

W

V12 Carrier wave output auto-control bit

V11 Timer 1 count source selection bit

V10 Timer 1 control bit

Note: “W” represents write enabled.

0 Auto-control output by timer 1 is invalid

1 Auto-control output by timer 1 is valid

0 Carrier output (CARRY)

1 Bit 5 of watchdog timer (WDT)

0 Stop (Timer 1 state retained)

1 Operating

(1) Control register related to timer

• Timer control register V1

Register V1 controls the timer 1 count source and auto-

control function of carrier wave output from port CARR by

timer 1. Set the contents of this register through register A

with the TV1A instruction.

(4) Timer 1 underflow flag (T1F)

Timer 1 underflow flag is set to “1” when the timer 1 underflows.

The state of this flag can be examined with the skip instruction

(SNZT1).

T1F flag is cleared to “0” when the next instruction is skipped

with a skip instruction.

(2) Precautions

Note the following for the use of timers.

• Count source

Stop timer 1 counting to change its count source.

• Watchdog timer

Be sure that the timing to execute the WRST instruction in

order to operate WDT efficiently.

• Writing to reload register R1

When writing data to reload register R1 while timer 1 is

operating, avoid a timing when timer 1 underflows.

(3) Timer 1

Timer 1 is an 8-bit binary down counter with the timer 1 reload

register (R1).

When timer is stopped, data can be set simultaneously in timer

1 and the reload register (R1) with the T1AB instruction.

When timer is operating, data can be set to only reload register

R1 with the T1AB instruction.

When setting the next count data to reload register R1 at

operating, set data before timer 1 underflows.

Timer 1 starts counting after the following process;

Πset data in timer 1,

 select the count source with the bit 1 of register V1, and

Ž set the bit 0 of register V1 to “1.”

Once count is started, when timer 1 underflows (the next count

pulse is input after the contents of timer 1 becomes “0”), the

timer 1 underflow flag (T1F) is set to “1,” new data is loaded

from reload register R1, and count continues (auto-reload

function).

When a value set in reload register R1 is n, timer 1 divides the

count source signal by n + 1 (n = 0 to 255).

Data can be read from timer 1 to registers A and B. When

reading the data, stop the counter and then execute the TAB1

instruction.

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