Kenwood TM-221A Service Manual page 6

Digital control unit
@ General
The control unit consists of a microprocessor, input
keys, peripheral circuits, and a display. The single micro-
processor (!C3) controls all transceiver functions. The pin
assignments of the microprocessor are listed on the
Table 6.
@ Keys and rotary encoder input circuits
Fig. 7 shows the input circuit for the keys and rotary
encoder. Data from the front panel keys, microphone
keys, and rotary encoder are applied directly to the
microprocessor,
Terminal
Xt 4.194304MHz crystal oscillator.
73
Not used;
CTCSS shift register reset
a! (K,M)
ee
Oo
O
cs a altale||2 Wid
Sis a|2 [ole
BS ral
SHIFT
5V
Not used.
Sauelch control during remote
38 P22 H 5 pi ?
control.
nee? 1 Reset input.
PO3/SI
PO2/SO
ie)
Shift register strobe.
Beep oscillator output.
Microphone DOWN switch input/
serial data input.
Microphone PTT switch input/
serial data input.
PO1/SCK
Microphone UP switch input/
serial data input.
Model setting : 'L'' for 144MHz
"H" for 430MHz band.
Backup detect input.
SHIFT switch input.
LCD driver data.
LCD driver clock.
LCD driver enable.
M.IN switch input.
VEO/M select switch input.
REV switch input.
Not used.
Frequency step select switch input.
SCAN switch input.
+
Directional input.
CTCSS switch input (K,M).
Alert switch input (T,W).
TONE switch input.
Not used.
Pull-down pin.
PLL and shift register clock.
PLL and shift register data.
PLL enable.
Not used.
[GND terminal (OV).
BUSY input.
Power supply pin (5V).
Encoder input.
{only when connected).
GND terminal (OV).
Remote connection detect input
ae etal
Tone detect input (when CTCSS
is on (KM).
CTCSS IC data (KM).
Not used.
RF meter analog input.
S meter analog input.
CTCSS IC clock.
DAC digital data output.
Table 5 yPD75106G-508-18B pin assignments (Control unit IC3)