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2.6 8254 Timer/Counter
The 8254 Programmable timer/counter has 4 registers from Base+0 through Base+3. For
detailed programming information about 8254, please refer to Intel‘s “Microsystem
Components Handbook”.The block diagram is as below.
Cin : clock input
Cout : clock output
INTCLK : internal clock
CN3 : connector CN3
Cin
Gate
Cout
Counter 0
Cin
Gate
Cout
Counter 1
Cin
Gate
Cout
Counter 2
4M
2M
INTCLK
VCC
10K
CN3. Pin 8
PACER CLK
JP9
2M
CN3.14
CN3.10
CN3.12
VCC
10K
CN3.6
The counter0, counter1 and counter2 are all 16 bits counter. The counter 1 and counter 2
cascade as a 32 bits timer.
A-812PG Hardware Manual (Ver.1.2, Sep/2005, IPH-004-12) -----
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