4-2-2 Operation

Timer Operation (timers 2, 3)

Settings for timer operation are listed below. Timer 2 is used as an example.

(1)Set the TM2EN flag of the timer 2 mode register (TM2MD) to "0" to stop the count operation of timer 2.

(2) Set the TM2CK2 0 flags of the TM2MD register to select fs, fs/4, fx, or synchronized fx as the clock source.

(3)Set the TM2PWM flag of the TM2MD register to "0" so that normal timer operation is selected.

(4)Set a value in compare register 2 (TM2OC).

(5)Set the TM2EN flag of the TM2MD register to "1" to start the timer.

(6)When timer 2 begins operation, binary counter 2 (TM2BC) will count upward from X'00'.

(7)When the value of binary counter 2 matches that of the TM2OC register, the timer 2 interrupt request flag is set, and the binary counter 2 is reset to X'00' and begins to count upward again.

Clock

TM4EN

Write to registers

TM4OCH, TM4OCL

Binary

04

05

06

07

08

09

00

counter 4

 

 

 

 

 

 

 

Chapter 4 Timer Functions

When servicing an interrupt, reset the timer 2 interrupt request flag before starting timer 2.

During a count operation, be careful if the value set in TM2OC is smaller than the value of binary counter 2, since the count-up operation will continue until overflow occurs.

If fx is to be selected as the clock source and the value of binary counter 2 is to be read during operation, select synchronized fx in order to avoid reading data that may be incomplete during count- up transitions. However, with synchronized fx, it is not possible to return from STOP/HALT modes.

Figure 4-2-1 Binary Counter 2 (TM2BC) Count Timing

If the TM2EN flag of TM2MD register is changed simultaneously with other bits, the switching operation may cause binary counter 2 to be incremented.

If the value of TM2OC register is overwritten while timer 2 has stopped counting, binary counter 2 will be reset to X'00' at the edge of next count clock.

The value of TM3CK0~2 of T3MD register is unsettled. If timer2/ timer 3 is independently used, any mode except cascade connection should be set.

8-bit Timer Operation (timers 2, 3)

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Panasonic MN101C00 user manual Operation, Binary Counter 2 TM2BC Count Timing