4513 datasheet(46/210 Pages) RENESAS

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4513/4514 Group User’s Manual

HARDWARE

1-33

FUNCTION BLOCK OPERATIONS

(1) Timer control registers

• Timer control register W1

of count start synchronous circuit, and the frequency dividing ra-

tio and count operation of prescaler. Set the contents of this

instruction can be used to transfer the contents of register W1 to

• Timer control register W2

timer 2. Set the contents of this register through register A with

the TW2A instruction. The TAW2 instruction can be used to trans-

fer the contents of register W2 to register A.

• Timer control register W3

timer 3 and the selection of count start synchronous circuit. Set

the contents of this register through register A with the TW3A in-

struction. The TAW3 instruction can be used to transfer the

contents of register W3 to register A.

• Timer control register W4

timer 4. Set the contents of this register through register A with

the TW4A instruction. The TAW4 instruction can be used to trans-

fer the contents of register W4 to register A.

• Timer control register W6

tions, the selection and operation of the CNTR0 and CNTR1

output. Set the contents of this register through register A with

the TW6A instruction. The TAW6 instruction can be used to trans-

fer the contents of register W6 to register A.

(2) Precautions

Note the following for the use of timers.

• Prescaler

Stop the prescaler operation to change its frequency dividing ra-

tio.

• Count source

Stop timer 1, 2, 3, or 4 counting to change its count source.

• Reading the count value

Stop timer 1, 2, 3, or 4 counting and then execute the TAB1,

TAB2, TAB3, or TAB4 instruction to read its data.

• Writing to reload registers R1 and R3

When writing data to reload registers R1 or R3 while timer 1 or

timer 3 is operating, avoid a timing when timer 1 or timer 3

underflows.

(3) Prescaler

Prescaler is a frequency divider. Its frequency dividing ratio can be

selected. The count source of prescaler is the instruction clock.

Use the bit 2 of register W1 to select the prescaler dividing ratio

and the bit 3 to start and stop its operation. Prescaler is initialized,

and the output signal (ORCLK) stops when the bit 3 of register W1

is cleared to “0.”

(4) Timer 1 (interrupt function)

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

ister (R1). Data can be set simultaneously in timer 1 and the reload

load register (R1) with the TR1AB instruction.

When writing data to reload register R1 with the TR1AB instruction,

the downcount after the underflow is started from the setting value

of reload register R1.

Timer 1 starts counting after the following process;

set data in timer 1, and

set the bit 1 of register W1 to “1.”

However, P30/INT0 pin input can be used as the start trigger for

timer 1 count operation by setting the bit 0 of register W1 to “1.”

When a value set in timer 1 is n, timer 1 divides the count source

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

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 interrupt request flag (T1F) is set to “1,” new data is loaded from

reload register R1, and count continues (auto-reload function).

Data can be read from timer 1 with the TAB1 instruction. When

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

struction. Timer 1 underflow signal divided by 2 can be output from

D6/CNTR0 pin.

(5) Timer 2 (interrupt function)

Timer 2 is an 8-bit binary down counter with the timer 2 reload reg-

ister (R2). Data can be set simultaneously in timer 2 and the reload

Timer 2 starts counting after the following process;

set data in timer 2,

select the count source with the bits 0 and 1 of register W2, and

set the bit 3 of register W2 to “1.”

When a value set in timer 2 is n, timer 2 divides the count source

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

Once count is started, when timer 2 underflows (the next count

pulse is input after the contents of timer 2 becomes “0”), the timer

2 interrupt request flag (T2F) is set to “1,” new data is loaded from

reload register R2, and count continues (auto-reload function).

Data can be read from timer 2 with the TAB2 instruction. When

reading the data, stop the counter and then execute the TAB2 in-

struction. The output from D6/CNTR0 pin by timer 2 underflow

signal divided by 2 can be controlled.

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