7480 datasheet(106/337 Pages) RENESAS

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7480 Group and 7481 Group User's Manual

1-89

1.12 Timer X and Timer Y

HARDWARE

When the timer X or Y write control bit is ‘0’, the CNTR pin output is initialized to HIGH by a write

to the timer ( in Figure 1.12.24). When it is ‘1’, however, the CNTR pin output level cannot be

initialized by a write to the timer. In the PWM mode, when the low-order byte of the timer becomes

‘0116’ in the LOW level of the PWM output ( in Figure 1.12.24), or when the high-order byte

becomes ‘0116’ in the HIGH level of the PWM output ( in Figure 1.12.24), an underflow occurs in

each timer at the subsequent rising edge of the count source and the output level of the CNTR pin

is inverted.

When ‘TLL (0016 through FF16)’ is written to the low-order byte of the timer and ‘TLH (0016 through

FF16)’ to the high-order byte, the duty cycle of the PWM waveform output from the CNTR pin is

expressed by ‘TLH/(TLH + TLL)’.

Notes 1: • All of the PWM outputs are HIGH when TLL = 0016 and TLH

≠ 0016.

• All of the PWM outputs are LOW when TLH = 0016.

2: When at least one of TLL and TLH is ‘0016’, no timer interrupt request can be generated.

3: Even when value ‘0016’ is written to a timer, the timer continues counting down. Therefore,

the contents of the timer are undefined.

Figure 1.12.24 Operation Example in PWM Mode

Count source

0016

TLH

Timer X stop

control bit

CNTR0 pin output

Writing to timer X

(high-order) (Note)

Time

Count start

Count stop

Count start

Timer X interrupt

request bit

Note: In this case, timer X write control bit is ‘0’ (writing to timer and timer latch simultaneously).

TLH

TLL

: Setting value to timer X (high-order)

: Setting value to timer X (low-order)

: PWM period T(s)=HH + HL

: Pulse width (HIGH-period)

: Pulse width (LOW-period)

: Clearing by writing ‘0’ to interrupt request bit or accepting interrupt request

HH(s) =

Count source frequency ×

Setting value to timer X (high-order)

TLL

Time

0016

HL(s) =

× Setting value to timer X (low-order)

: Contents of timer latch is reloaded

: Underflow

Writing to timer X

(low-order) (Note)

Undefined

‘0’ is written

‘1’ is written

Initialized to HIGH when

writing to timer X (Note)

0116

Count source frequency

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