TKR-851
15
5. Control Circuit
The control circuit mainly located in the control section of
TX-RX unit (X57-696 B/2) consists of the following : 5-1 CPU,
5-2 memory circuit, 5-3 CPU clock shift, 5-4 shift register cir-
cuit, 5-5 display circuit, 5-6 DSP circuit, 5-7 base-band circuit,
5-8 RS-232C circuit, 5-9 power supply circuit, and 5-10 5-tone
decode circuit.
5-1. CPU
The CPU (IC604) is a 16bit single-chip microcomputer con-
taining a 32k ROM and 3k RAM. This CPU controls the flash
ROM, the DSP, the receiver circuit, the transmitter circuit,
the control circuit, and the display circuit and transfers data to
or from an external device.
5-2. Memory Circuit
IC609 has a flash ROM with a capacity of 2M bits that
contains the control program for the CPU, the signal process-
ing program for DSP and data such as channels and operating
features.
This program can be easily written from an external de-
vice. Data such as the operating status are programmed into
the EEPROM (IC600).
5-3. CPU Clock Shift
There are the 14.754MHz clock for the CPU (IC604) and
the 16.515MHz clock for the DSP (IC618) at the control sec-
tion of TX-RX unit (X57-696). When these clocks are multi-
plexed with the reception frequency, they become an inter-
nal beat signal. To prevent this, by tuning Q600 and Q604 on
the clock frequency is shifted. (Shift on/off can be set
through programming.)
5-4. Shift Register Circuit
Serial data is sent to the shift register (IC502 to IC505 lo-
cated in display unit, IC602, IC623, IC7 located in TX-RX unit)
from the CPU (IC604) to control various functions in the unit.
5-5. Display Circuit
The display circuit (X54-333) contains two 7-segment
LEDs D506, D507 (orange : see the operation manual for de-
tails of display), D503 (red : transmission), two-color D504
(green : busy, orange : selective called), two-color LED D505
(red : backup, green : main DC), LEDs in switches S501 to
S506, IC502, IC503, IC504, and IC505 to display this model
channels and states.
IC502 to IC505 are shift registers which convert serial data
from the CPU to parallel data and light LEDs.
Q507, Q510, and Q511 are switching transistors which
control two-color LED D505.
IC506, and IC507 are three-pin power supply ICs which
produce power used for the display circuit.
EEPROM
IC600
TX-RX unit (X57 B/2): CONTROL
IC601
SW
Q600
X600
BEAT
SHIFT
Reset IC
14.754
MHz
SW
Q600
X601
BEAT
SHIFT
16.515
MHz
FLASH ROM
CPU
IC609
IC620
232C DRIVER
IC615
D/A IC
IC602/623
Shift Register IC
INTERFACE IC
IC603/606
DSP
IC618
CODEC IC
IC614
DIVIDER
IC613
IC604
CLK,SOE,
STB1
SO
SO
SO
KEY1~5
KEY LAMP
1~6
Display unit (X54-3330-21 A/2)
BUSY
CALL
Main DC/
BACKUP
Shift Reg. 1
BU4094BCFV
SI
SI
SI
DAT
Shift Reg. 2
BU4094BCFV
Shift Reg. 3
BU4094BCFV
Shift Reg. 4
BU4094BCFV
PF1~6
SW
SW
SW
SW
SW
SW
CLK,SOE,
STB1
CLK,SOE,
STB1
CLK,SOE,
STB1
TX
SW
Fig. 8
Control circuit
Fig. 9
Display circuit
CIRCUIT DESCRIPTION
