Advantech PCM-3753I, User Manual

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PCM-3753I User Manual 10
Using Jumpers to Set Ports as Output Ports
By shorting the two pins of the jumpers JPA0, JPB0, JPC0L, JPC0H,
JPA1, JPB1, JPC1L, JPC1H, JPA2, JPB2, JPC2L, JPC2H, JPA3, JPB3,
JPC3L or JPC3H, a user sets the corresponding ports to be output ports.
(JPA0 means jumper for port A0, JPB0 means jumper for port B0, etc.)
Shorting the two pins of a port's jumper disables the port from being soft-
ware configurable as an input port. The initial state of each of these ports
after system power on or reset will be logic 0 (voltage low), unless
jumper JP1 determines otherwise. (See JP1 below.)
Jumper JP1 Restores Ports to Their Condition Prior to Reset
Jumper JP1 gives the PCM-3753I a new and valuable capability. With
JP1 enabled (i.e., by shorting the lower two pins of JP1), the
PCM-3753I "memorizes" all port I/O settings and output values, and, in
the event of a "hot" reset, the settings and output values present at the port
just prior to reset are restored to each port following reset. This feature
applies to both ports set by software, and to ports configured as output
ports via jumper. Depending on the application, this capability may allow
a card to be reset without requiring a complete shutdown of processes
controlled by the card (since port values are left unchanged and are inter-
rupted only momentarily).
Complete loss of power to the chip clears chip memory. Thus, even if
JP1 is enabled, if the power to the card is disconnected, the card's initial
power-on state will be the state of an input port with voltage high input
(for software-set ports) or the state of an output port with voltage low out-
put (for jumper-set ports).
When jumper JP1 is not enabled both power-off and reset results in ports
returning to the state of an input port with voltage high input or returning
to the state of output port with voltage low output (for jumper-set ports).
Table 2.1: Summary of Jumper Settings
Jumpers Function Description
JP1 Keep the last digital output
status after hot reset
JP1 Load default configuration while
hot reset (Default)