MSM80C154S/83C154S/85C154HVS80S1 S2 S3 S4 S5 S6M1S1 S2 S3 S4 S5 S6M1 or M2S1XTAL1 10ALE 10T0 or T1COUNT IN10F/F2Q 10TIMER COUNT 10F/F1Q 10S2S6Figure 4-9 Detector circuit operational time chart4.5.2.4 Counting control of timer/counters 0 and 1 by INT pinIn addition to control by TR0 and TR1 bits of timer control register (TCON), timer/counter 0and 1 counting start and stop can also be controlled by the signal level applied to the externalinterrupt pin in accordance with the GATE data values of bits 3 and 7 in the timer mode register(TMOD 89H) indicated in Table 4-9.Timer/counter 0 is controlled by the bit 3, GATE bit. When the GATE bit is “0”, counting isstarted and stopped only by TR0.When the GATE bit is “1”, counting in timer/counter 0 is enabled if the TR0 bit and INT0 pininput signal are both “1”. Counting is subsequently stopped if either is changed to “0” level.Timer/counter 1 is controlled by the bit 7, GATE bit, the functional operation being the sameas timer/counter 0. The GATE - INT timer/counter counting control circuit is outlined in Figure4-10, and the control table is given in Table 4-10.Table 4-9 Timer mode register (TMOD 89H)Timer 1 Timer 0BitFlagSet7 6 5 4 3 2 1 0GATE C/T M1 M0 GATE C/T M1 M0• •
