User's Manual

Front Panel Interface
46
Signal Name Backplane Backplane Signal Type Description
Front Panel Pin
Fault Anode J19-1C J22-26 Drive voltage to Voltage is derived from the +5 supply which is
the fault LED passed through a resistor to supply the anode of
the fault LED
Fault Cathode J19-2C J22-25 Discrete open Provides a pull down to turn on fault LED
collector output
Operate Anode J19-3C J22-24 Drive voltage to Voltage is derived from the +5 supply which is
the operate LED passed through a resistor to supply the anode
of this LED.
Operate Cathode J19-4C J22-23 Discrete open Provides a pull down to turn on operate LED
collector output
S5 J19-5C J22-21 Discrete contact S5 is the switch on the far right of the front panel
closure input For this switch and the five listed below a contact
closure or low indicates the switch has been
depressed
S4 J19-6C J22-20 Discrete contact second from the right on the front panel
closure input
S3 J19-7C J22-19 Discrete contact center switch on the fron panel
closure input
S2 J19-8C J22-18 Discrete contact second from the left on the front panel
closure input
S1 J19-9C J22-17 Discrete contact first switch on the left of the front panel
closure input
V
ss
(GND) J19-10C J22-16 Ground Provides a return to the front panel board
V
cc
(+5V) J19-11C J22-15 +5V Power Provides +5V to the front panel display logic.
V
EE
(Contrast) J19-12C J22-14 Control Voltage Controls the contrast of the LCD
Output 0 to 5V
RS J19-13C J22-13 Discrete TLL / HMOS Indicates to the display is an instructino or
Output data command is being sent. High indocates
the byte is being written as data, low
indicates that an instruction command is
being written to the display.
RW J19-14C J22-12 Discrete TTL / HCMOS Indicates if data transfer to the display is read
Output or write. A high indicates that the microcontroller
is reading data from the display while a low
indicates that data is being written to the display
E J8-15C J22-11 Discrete TTL / HCMOS Indicates the transfer of data to / from the display
Output During a write operation data is transferred to the
display on a high to low transition of the signal.
During a read operation the display will drive the
data bus when high
DB0-DB7 J19-16C to 23C J22-10 to 3 Discrete TTL / HCMOS Data lines which pass data between the display
Bidirectional Data Lines and the control board.
Anode (+) Backlight J19-24C J22-2 Control voltage output Provides voltage to the LCD backlight in the
3.8 - 4.6V display
Cathode Backlight J19-25C J22-1 Control Voltage return Return for the control voltage specified above