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The Recorder Board - 0670-00-0386
The Recorder Head Register
U6 controls the eight vertical dots of the thermal print head directly through the print
head drivers, U1 and U2, UDN2543. The software is responsible for turning the print
head on and off at about 250 Hz.
Dot 1 [|]
Dot 2 Г]
Dot 3 []
:
Dot 4 [7]
2.75mm
Dot5 [_]
Dot6 [ |
Dot 7 [7]
Dot 8 {_]
FIGURE 1-6
DOT PLACEMENT AND CHARACTER SIZE
The Recorder Motor Register
The most significant four bits of US controls the four control lines to the paper feed
step motor in the recorder via motor driver U4, UDN2543. The least significant four
bits of U5 controls the four control lines to the head feed step motor in the recorder
via motor driver U3, a UDN2543. The four control lines to each motor are pulsed se-
quentially at about 250Hz to produce the desired stepping of the motors.
The Watchdog Timer
U7, a DS1232, is a watchdog timer that will clear both recorder registers if the re-
corder head register has not been strobed for about 150 msec. It also resets both
registers on power-up. The maximum reset active time is about one second. A jumper
JP1 allows the optional removal of the watchdog timer and using the system reset line,
GLR*, to clear the recorder head and recorder motor registers. JP1 is normally open.
The Recorder
The recorder mechanism is a Seiko STP211-144 thermal recorder. The horizontal
resolution is 144 pixels, which will generate 24 characters per line if a 5x7 character
matrix is used. The home position switch will open when the recorder print head is in
left most position, causing the HOME* signal to go high, (pull up resistor on interface
board). The recorder runs at +5vV that is filtered by LC circuit, L1 and C6.
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