Backup Circuit; Eeprom; Busy Signal; Encoder Circuit - Kenwood TK-80 Service Manual

TK-80

5-3. Backup circuit

This transceiver has two kinds of data stored in the micro-
computer and EEPROM. Setting value of user and dealer
menu data, such as memory channel data No. 01 to 80, is
stored in the microcomputer, and memory channel data No.
01 to 10 for adjustment data, is stored in the EEPROM. To
backup the CPU a power supply is needed. If 14V is cut off,
power is supplied from a lithium battery. To retain data with
the lithium battery, the microcomputer must be in backup
mode. So, the backup detection circuit detects a voltage
drop in the 14V line and outputs a backup request signal to
the microcomputer (Fig. 10).
14V
Q1
D4
Fig. 10 Backup detection circuit

5-4. EEPROM

Adjustment data and memory channel No. 01 to 10 stored
in the EEPROM, which consists of 256 16-bit registers. Data
can be written to and read from the EEPROM. Each time the
power is switched on, data is read from the EEPROM. If
corrupt data is detected, the default adjustment data is used
and memory channel is cleared. Adjustment data can be
written into the EEPROM in servicing mode.
Memory channel is written by dealer mode (Fig. 11).
5V
IC6
EEPROM
Fig. 11 EEPROM circuit
2
1
18
CIRCUIT DESCRIPTION
5C
IC5
CPU
D5
3
BKC
Q2
IC5
12
PDA
CPU
19
PCK
TX-RX UNIT
CN14
TXD 5
4
RXD
3
CTS
2
3 RTS
4
6
5
J1
Fig. 13 Serial interface

5-5. Busy signal

The level of the port is monitored in receive mode, and
busy indication and busy stop are performed during scan.

5-6. Encoder circuit

The encoder is a mechanical one. The waveforms of the
encoder pulses are rectified by IC1 and IC2 in the LCD as-
sembly, and the number of pulses is counted by the hard-
ware counter in the microcomputer (Fig. 12).
5V
IC5
CPU
IC1
6
CK1
7
CK2
IC2
5-7. Serial interface
The CPU has a synchronous serial interface built in, en-
abling serial communication at the TTL level.
The TK-80 can use this serial port for control via an exter-
nal personal computer or for transmission of data among two
transceiver units.
The data format is: TTL level, 8 data bit length, 1 stop bit,
no parity, 9600 bps transmission speed (Fig. 13).
5-8. Key scan
The key scan consists of the six elements S0 and K0 to
K4.
When the panel switch is pressed, the K0 to K4 port be-
comes "L" level and detection can be done by software.
Also, through the dealer menu settings, software can be
used to set actuation enable/disable for each of the switches
"SCAN", "MENU", "MODE" and "DATA".
5V
CONTROL UNIT
CN4
TXD
RXD
CTS
RTS
CN1
CN1
EDP1 EDP1
16 11
EDP2 EDP2
15 12
CONTROL UNIT LCD ASSY
Fig. 12 Encoder circuit
8 9
59
TXD
5 6 60
RXD
3 4 62
CTS
2 1 61
RTS
IC8
IC5
CPU
A
COM
B
S1
Encoder