RPR 550IS Series
Page 3 - 14 TM1188 Issue 1
Vibrate Alert Drive Circuit
42. The vibrate alert option is provided by a capsule which plugs into the battery
compartment instead of the `AA' cell. The capsule contains the motor with an
eccentric weight and a battery holder for an `N' cell. Pin 15 of gate array IC2
generates a `vibrate enable' signal which enables TR26 and TR6, connects the vibrate
motor to 0V and subsequently causes the vibrate alert to operate. Resistor R2 and R9
are IS components and provide infallible isolation of the power available from R1A or
R1B to the vibrate driver from the rest of the circuitry. R1A is fitted to the
RPR 552IS/553IS and R1B is fitted to the RPR 551IS.
Liquid Crystal Display Module
43. The Liquid Crystal Display (LCD) module consists of a driver chip, a liquid crystal
display and five resistors forming a bias chain. The driver chip interfaces to
microprocessor IC3 via a four bit port with three control lines and an additional line to
turn the bias chain on and off. The lines are shown in Table 1.
Table 1: LCD Module
NAME PIN DESCRIPTION SIGNAL
SBY 3 Controls the bias chain 0 = bias chain on, display visible
1 = bias chain off, display blank
RS 4 Selects which register 0 = instruction register
1 = data register
IC-2 5 On-icon drive Input two
E 6 Operation start signal Consists of pulses
IC-1 11 On-icon drive Input one
DB4,5,6,7 7,8,9,10 Data bus Data
44. The voltage supply, a nominal 5V, is available on pin 2. The ON icon is driven by a
128Hz signal from TSF, pin 42 of IC2, via TR18 and associated circuitry. The 128Hz
causes TR18a and TR18b to be enabled alternately (when TR18a is on TR18b is off
and vice versa) making pins 5 and 11 of the module become high and low alternately,
so enabling the ON icon.
Permanent On
45. Permanent On is a hardware option. Resistor R79 is only fitted to the Permanent On
option and R78 is omitted.
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