INTERNAL SPECIFICATIONS

4.5.2.5.6 32-bit timer mode

When “1” is set in bit 6 (T32) of the I/O control register (IOCON 0F8H), timer/counters 0 and 1 are connected serially as indicated in Figure 4-18 to become a 32-bit timer/counter.

This 32-bit timer/counter is started by the following procedure. First, “0” is set in TR0, TR1, TF0, and TF1 of the timer control register (TCON 88H) to stop the timer/counter and reset the timer flag.

Next timer/counter preset data values are set in timer/counters 0 and 1, and a counter clock designation is set in bit 2 (C/T) of the timer mode register (TMOD 89H).

If “1” is then set in bit 6 (T32) of the 1/0 control register (IOCON 0F8H) after completing the above procedure, the 32-bit timer/counter is established and counting is commenced. This 32-bit timer/counter is especially useful in cancelling CPU power down mode. (See power down mode cancellation.)

T0 PIN

 

DETECTOR

 

 

 

 

(PORT 3.4)

 

 

IOCON [0F8H]

 

 

 

 

7

6

5

4

3

2

1

0

XTAL 1

12

T32

SERR

IZC

P3HZ

P2HZ

P1HZ

ALF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Q0-----Q7 Q0-----Q7 Q0-----Q7 Q0-----Q7

 

 

 

TL0

 

TH0

TL1

 

TH1

 

TF1

 

 

(8BITS)

 

(8BITS)

(8BITS)

(8BITS)

 

 

 

C/ T (TMOD bit2)

Figure 4-18 32-bit timer/counter

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Sonic Alert msm83c154s, msm80154s, msm85c154hvs 2.5.6 32-bit timer mode, T0 PIN Detector, Iocon 0F8H, Serr IZC, TF1 8BITS