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Installation
2.6 Pull-Up and Pull-Down Setting
The input / output ports of PET-48DIO emulate as two Intel 8255
general purpose programmable peripheral interfaces(PPI). Figure 2.2
shows PET-DIO48's I/O ports equally block diagram.
PC0
PB0
P A 0
PC1
PB1
P A 1
#2 8255
#1 8255
C N 2
C N 1
Figure 2.3 I / O port's block diagram
There are six build-in jumpers on PET-48DIO for pull up and pull down
the I/O ports. The PET-48DIO can pull up PA, PB, PC to +5V, and pull
down PA, PB, and PC to ground.A typical application where pull up
resistors are used to monitor switch closure.
One network( Figure 2.4) is associated with each group of line. These
networks can be quickly connected to a voltage source (pull up) or
ground (pull down) through on board jumper setting.
The Pull-Up and Pull-Down configuration of each port is set by the
jumper JP1, JP2, JP4, JP6, JP7, and JP9, respectively. The port
configuration and its corresponding jumper are listed in below table.