Sharp ER-A520 Service Manual page 12

5. A/D CONVERSION
In the ER-A520/530, the following three kinds of signals are inputted to
the A/D conversion port.
<CPU PORT>
Signal to
No. CPU PORT
be used
130 AN0 TM
138 AN1 VPTEST
137 AN2 VREF
5-1. PRINTER HEAD TEMPERATURE MONITOR
A voltage divided by the temperature detection thermistor of the printer
head and the resistor is inputted to AN0 pin.
The printer head conduction must be controlled as shown below.
HEAD A/D CONVERSION
TEMPERATURE VALUE (DEC)
-10°C or below 929~1023
-10°C ~ 0°C 869~928
0°C ~ 70°C 232~868
70°C or above 0~231
5-2. PRINTER HEAD VOLTAGE MONITOR
A voltage is supplied by the printer head power source, passed through
the printer, and divided by the resistor is inputted to AN1 pin.
The A/D conversion value must be read after turning VHCOM signal
(CPU P106) to "H" and stabilizing the voltage (after 10msec).
The printable voltage range of the printer is 15V~26V. The voltage is
calculated from the AN1 value and the A/D conversion value of the ref-
erence voltage.
5-3. REFERENCE VOLTAGE
The reference voltage (2.495V m 0.085V) generated by KIA431F is input-
ted to AN2 pin.
469 (DEC) t VREF t 557 (DEC)
VREF 469 (DEC) corresponds to VREF = 2.41V at VCC = 5.25V
VREF 557 (DEC) corresponds to VREF = 2.58V at VCC = 4.75V
Function
PRINTER HEAD TEMPERATURE
MONITOR
PRINTER HEAD VOLTAGE MONI-
TOR
REFERENCE VOLTAGE
OPERATION
MOTOR LOCK
PRINT IN ENERGIZING
TIME AT 0°C
PRINT FOR CONDUCTION
TIME SPECIFIED ON PR-
58H CONTROL SPEC.
MOTOR LOCK
ER-A520U/ER-A530U HARDWARE DESCRIPTION
6. KEY/DISPLAY
6-1. LCD CONTROL
LCD control is same as the ER-A275P.
LCD-related Register
Function
LCD Write Data
LCD Read Data
<CPU PORT>
Signal to
No. CPU PORT
be used
90 P120 BLON
89 P121 LCDON
88 P122 LRS
87 P123 LR/W#
86 P124 LE
85 P125 DATALE
P125: LWDL
L : LCD write data latch
P124: E
Enable Signal
P123: R/W#
H: Data read L: Data Write
P122 LRS
H: Data input L: Instruction Input
DATA WRITE (CPU 3 LCD)
LRS
LR/W#
LE
DB0-7
LWDL
P122 "x" 100001h
P123 "L" DATA
WRITE
DATA READ (CPU 1 LCD)
LRS
LR/W#
LE
DB0-7
LWDL
P122 "x" P125 "H" P124 "H" 100001h
P123 "H"
When the read busy flag of the LCD display remains busy for more than
500ms, turn off LCDON (P121) for 1ms and perform initializing.
– 11 –
Address
100001h
100001h
Function
LCD BACK LIGHT ON SIGNAL
LCD ON SIGNAL
LCD RS SIGNAL
LCD R/W# SIGNAL
LCD E SIGNAL
LCD WRITE DATA LATCH
Enable
Valid Data
P124 "H" P124 "L" P123 "H"
Valid Data
P124 "L" P125 "L"
DATA
READ
R/W
W
R