USER'S GUIDE

Mode 1

Mode 1 for both programmable timers operates in an identical fashion described for Mode 0, except Mode 1 configures a 16±bit timer/counter register. In this case, for Timer 0, TH0 contains the most significant eight bits of the count value while TL0 holds the least significant eight bits. Timer 1 uses TH1, TL1 in an identical fashion in Mode 1. Figure 13±3 is also a diagram depicting op- eration in Mode 1 for the timer/counters.

Mode 2

The selection of Mode 2 configures an 8±bit timer/ counter with automatic reload of a value preset by soft-

ware. Figure 13±4 illustrates a functional block diagram of this operational mode. When Timer 0 is used in Mode 2, TL0 is incremented as each count is received. When the value of 0FFH (all 1's) is reached, TF0 will be set on the next count and the reload value held in TH0 will be transferred into TL0. TH0 remains unchanged until it is modified by the application software.

Timer 1 operates in an identical fashion when it is set for operation in Mode 2.

TIMER/COUNTER MODE 2 OPERATION Figure 13±4

 

TF0

INTERRUPT

7

TL0

0

RELOAD

 

 

 

TH0

 

T0

 

 

 

 

1

 

 

MUX

 

DIVIDE

0

OSC.

 

BY 12

TR0

 

1 IF C/T = 1

0 IF C/T = 0

GATE

INT0 PIN

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Mitsubishi DS907x SIP, DS5000TK manual TIMER/COUNTER Mode 2 Operation ±4, 108