Renesas 4514 Manual De Usuario

2-24

4513/4514 Group User’s Manual

0

b3

b0

➀

 Disable Interrupts

Timer 4 interrupt is temporarily disabled.

Interrupt enable flag INTE

Interrupt control register V2

“0”

✕

✕

✕

All interrupts disabled (DI instruction)

Timer 4 interrupt occurrence disabled 
(TV2A instruction)

b3

b0

0 1

➁

 Stop Timer Operation

Timer 4, timer 3 and prescaler are temporarily stopped.
Dividing ratio of prescaler is selected.

Timer control register W1

✕

Prescaler stop (TW1A instruction)
Prescaler divided by 16 selected

Timer 3 stop (TW3A instruction)
Prescaler selected for count source

Timer 4 stop (TW4A instruction)
Timer 3 underflow signal selected for count source

b3

b0

0

1

0

Timer control register W3

✕

✕

b3

b0

0

0

0

Timer control register W4

✕

➂

 Set Timer Value

Timer 3 and timer 4 count times are set. (The formula is shown 

❈

A below.)

Timer 3 reload register R3
Timer 4 reload register R4

“52

16

”

“F9

16

”

Timer count value 82 set (T3AB instruction)
Timer count value 249 set (T4AB instruction)

➃

 Clear Interrupt Request

Timer 4 interrupt activated condition is cleared.

Timer 4 interrupt request flag T4F “0”

Timer 4 interrupt activated condition cleared 
(SNZT4 instruction)

Note when the interrupt request is cleared

When 

➃

 is executed, considering the skip of the next instruction according to the 

interrupt request flag T4F, insert the NOP instruction after the SNZT4 instruction.

b3

b0

0

1

1

➄

 Start Timer 4 Operation

Timer 4, timer 3 and prescaler temporarily stopped are restarted.

Timer control register W3

Timer 4 operation start (TW4A instruction)

Timer 3 operation start (TW3A instruction)

Prescaler operation start (TW1A instruction)

✕

b3

b0

1 1

Timer control register W1

✕ ✕

Timer control register W4

b3

b0

0

1

0

✕

b3

b0

1

➅

 Enable Interrupts

The timer 4 interrupt which is temporarily disabled is enabled.

AAAAAA

AAAAAA

Interrupt control register V2

Interrupt enable flag INTE

“1”

Timer 4 interrupt occurrence enabled 
(TV2A instruction)
All interrupts enabled (EI instruction)

✕

✕

✕

Constant period interrupt execution start

❈

A The prescaler dividing ratio, time 3 count value and timer 4 count value to make the interrupt occur 

every 250 ms are set as follows.

250 ms 

≅

 (4.0 MHz)

✕

 

3

✕

16

✕

(82+1)

✕

 (249+1)

–1

System clock Instruction 

clock

Prescaler 
dividing
ratio

Timer 3
count 
value

Timer 4
count 
value

“

✕

”: it can be “0” or “1.”