Siemens EF 88H Series Bedienungsanleitung PDF herunterladen (Seite 55)

Semiconductor Group 6-21

On-Chip Peripheral Components

C501

6.2.1.5 Mode 3

Mode 3 has different effects on timer 0 and timer 1. Timer 1 in mode 3 simply holds its count. The

effect is the same as setting TR1=0. Timer 0 in mode 3 establishes TL0 and TH0 as two seperate

counters. The logic for mode 3 on timer 0 is shown in figure 6-14. TL0 uses the timer 0 control bits:

C/T

, Gate, TR0, INT0 and TF0. TH0 is locked into a timer function (counting machine cycles) and

takes over the use of TR1 and TF1 from timer 1. Thus, TH0 now controls the “timer 1” interrupt.

Mode 3 is provided for applications requiring an extra 8-bit timer or counter. When timer 0 is in

mode 3, timer 1 can be turned on and off by switching it out of and into its own mode 3, or can still

be used by the serial channel as a baud rate generator, or in fact, in any application not requiring

an interrupt from timer 1 itself.

Figure 6-14

Timer/Counter 0, Mode 3: Two 8-Bit Timers/Counters

MCS02096

OSC

C/T = 0

TL0

TF0

C/T = 1

(8 Bits)

TR1

Gate

P3.2/INT0

Control

Interrupt

(8 Bits)

TH0

Interrupt

TF1

Control

TR1

/12

OSC

/12

P3.4/T0

÷ 12

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Siemens EF 88H Series Bedienungsanleitung Seite 55