ADLINK Technology PCI-7200 Spécifications télécharger pdf (Page 87)

8254 Programmable Interval Time •• 77

• M2, M1 & M0 - Select Operating Mode (Bit 3, Bit 2, & Bit 1)

M2 M1 M0 MODE

0 0 0 0

0 0 1 1

x 1 0 2

x 1 1 3

1 0 0 4

1 0 1 5

• BCD - Select Binary/BCD Counting (Bit 0)

0 BINARY COUNTER 16-BITS

1 BINARY CODED DECIMAL (BCD) COUNTER (4

DECADES)

Note:

1. The count of the binary counter is from 0 up to 65,535.

2. The count of the BCD counter is from 0 up to 99,999.

A.3 Mode Definition

In 8254, there are six different operating modes can be selected.

The they are :

• Mode 0 : interrupt on terminal count

The output will be initially low after the mode set operation.

After the count is loaded into the selected count register, the

output will remain low and the counter will count. When

terminal count is reached, the output will go high and remain

high until the selected count register is reloaded with the

mode or a new count is loaded. The counter continues to

decrement after terminal count has been reached.

1 2 ... 82 83 84 85 86 87 88 89 90 91

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ADLINK Technology PCI-7200 Spécifications Page 87