Adlink PCI-8554 Manual do Utilizador descarregar pdf (Página 42)

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Signal Connection and Applications

4.4 Frequency Generator

4.4.1 To generate a 250 KHz Square Wave.

Step 1: Use a fixed clock source because the output is a fixed

frequency.

Step 2: The internal 8MHz clock is capable of generating the

250KHz frequency. Use Counter 1 for this application.

∴

250 kHz = 8MHz/32

Step 3: The gate source should be set to “enable” always and

therefore GATE1 is let open (pin 99 of CN1).

Step 4: Connect the counter output to an external device and

write the control program. Refer to ‘DEMO1.C’

source code.

COUT1

Counter #1

8254 Chip #1

'H'

ECK1

GND

CK1

COUT10

8MHz

COUT11

set by function "8554_SET_cntCLK"

set by function

"_8554_SET_CK1"

Figure 20: Example of a frequency generator (1)

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 66 67

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Adlink PCI-8554 Manual do Utilizador Página 42