Illinois Tool Works IJ300, Operation Manual

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Controller
Appendix B: Theory of Operation
Page 78 of 115 5760-121 Operations Manual Rev B
CPU Board
The CPU Board has two microcontrollers, an LCD controller, flash memory, SRAM, a real
time clock/calendar, an Ethernet port, two serial ports, 12V, 5V and 3.3V regulators, a 3V
battery, and PC/104 bus connectors.
Of the two microcontrollers, one (U13) is the IJ3000's central processing unit (CPU). It exe-
cutes the system program from flash and SRAM. The other microcontroller (U21) controls
the keyboard and touch screen, decoding user inputs and sending appropriate commands
to the CPU.
The LCD controller (U22) contains the display RAM, as well as all circuitry needed to read
the display RAM, format its data and send it to the LCD with the necessary control signals
so that what is seen on the display is of some use. The CPU writes display data into the
display RAM.
The real time clock and calendar (U2) keep system time.
The 3V battery (BT1) preserves system data and keeps the clock running during power
outages or when the IJ3000 is not plugged into a power outlet.
Test Points: TP1: 12VDC, Power for backlight. Turns on/off with soft power switch.
TP2: GND.
TP3: 5VDC, Power for 5V logic.
TP4: 3.3VDC, Power for 3.3V logic.
LEDs: D2: Green. 5VDC present indicator.
D3: Yellow. Flashes when the CPU is running.
D21: Ethernet connector, Green. Flashes to indicate network traffic.
D22: Ethernet connector, Red. Indicates valid network connection.
Jumpers: J3: Flash Lock; used during CPU board manufacture. There
should be no jumper during normal operation.
J8: Used during CPU board manufacture. There should be no jumper
during normal operation.
JP3: Used during CPU board manufacture. There should be no jumper
during normal operation.
YELLOW
LED
GREEN
LED
D22
D21
P2
P1
J5
D2
D3
J3
TP1
JP1
J2
J1
J4
TP4
BT1
P3
GREEN LED, VISIBLE
ON THE CONNECTOR
VIA A LIGHT PIPE
RED LED, VISIBLE
ON THE CONNECTOR
VIA A LIGHT PIPE
CPU BOARD
U22
U21
U13
U2