Panasonic UF-890 Service Manual page 242

6.2.10 Control Panel
The Control Panel consists of the Display PCB and Panel Unit, which display various status information. It
is normally interfaced to the main CPU. Keyed input signals are received by the Panel CPU and the data is
transferred to the main CPU on the FCB PC Board.
The Control Panel performs the following processes simultaneously:
• Key inputting
• LED, LCD display
• Data transmission / reception
Interface to main CPU
The interfacing between the main CPU and the panel CPU are all executed with commands and responses
in the following two formats:
• Command / response (1 byte) + number of data + check sum
• Command / response (1 byte) + number of data + data 1 + data 2 ........................ + data n + check sum.
PNL CPU (IC1)
13
From
/to
LED, KEY scanning
FCB
LED, KEY scanning
PCB
PNLCK
PNLRD
PNLSD
PNLRST
nPSAVE
nWAKUP
BATVOL
BZCLK
+5V
+5VP
(Not
+24V
use)
GND
GND
KIN (7:0)
LCD Unit
20 characters, 2 lines,
5x7 dots control
LEDCT (1:0)
2
8
LED
LED (7:0)
Key matrix
(71 keys)
10
SCN (9:0)
8
Control Panel PC Board
242