ADLINK Technology cPCI-9116 Podręcznik Użytkownika Pobierz pdf (Strona 60)

50 • Operation Theory

• Two programmable timer modes are provided:

Mode 0: Interrupt on Terminal Count

Mode 0 is typically used for event counting, as illustrated in fig 20. After the

initial count is written, OUT is initially low, and will remain low until the

Counter counts to zero. OUT then goes high and will remain high until a

new count is written into the Counter.

3

3

2

1

1

1

0

0

0

Gate

CLK

Count value

OUT

Mode 0, Initial count=3, Count down

Figure 20: Mode 0 Operation

Mode 1: Rate Generator

This mode operates like a divide-by-N counter, as illustrated in fig 21. After

the initial count is written, initially OUT is low. When the counter reaches 1,

OUT goes high for one clock pulse. OUT then goes low again. The counter

reloads the initial count and the process will be repeated.

3

3

2

2

1

3

2

1

3

Gate

CLK

Count value

OUT

mode 1, Initial count=3, Count down

Figure 21: Mode 1 Operation

Note: In Mode 1 the initial count value N must be larger than one.

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