Kenwood TM-221A Service Manual page 9

@ Alert and electronic volume contro! output (when
optional remote controller is connected)
The alert and electronic volume contro! outputs are
provided by pins P92 (CK), P91 (DT), and P21 (ST) of
the microprocessor to the 8-bit shift register (1C3) in
the TX-RX unit. P92 (CK) and P91 (DT) are also used for
the PLL data. Fig. 13 shows the data transfer format.
Fig. 14 shows the data configuration.
Bbit
DT
MSB LSB
: |
Fig. 13 Data transfer format for alert and
electronic volume control
control
DOWN
UP
D6 to D8 when the
remote controller
Electronic =
Alert control
Fig. 14 Data configuration for alert and
electronic volume control
@ Tone output
The outputs from pins P40 to P43 and P50 to P53
of the microprocessor are applied to a ladder resistance
network (IC4) which converts these signals into an analog
waveform with 38 possible tone frequencies combinations
67.0 to 250.3Hz. Fig. 15 shows the internal configuration
of IC4,
P53
P52
P51
P50
P43
P42
P41
P40
{option) is connected.
TM-221A/E/ES
CIRCUIT DESCRIPTION
@ S-meter and RF meter input
The analog voltage of the S-meter is applied to pin
PTHOO of the microprocessor, and the analog voitage of
the RF meter to pin PTHO1. After 4-bit (16-step) analog-
to-digital conversion, the resulting signal is sent to the
display.
@ Busy input
When squelch is ON and an input signal is present, a
tow input lights the busy indicator.
@ CTCSS unit (option : TM-221A only) input and output
The microprocessor sends data from pins P30, P31, and
P61 to the CTCSS unit. Fig. 16 shows the data transfer
format. Fig. 17 shows the data configuration. When a tone
is detected from the CTCSS unit, a '''H"' is applied to pin
P32 of the microprocessor to open the squelch.
8bit
cTc Ii
CTD
MSB LSB
cTSs |
Fig. 16 CTCSS data transfer format
CTCSS unit MN6520 tone frequency select data
pet G2 es] BF | 26)
Ex.885Hz LH LE H H 4H
Fig. 17 CTCSS data configuration
@ Remote control (RC-10) (option) input and output
When the RC-10 remote control unit is connected a
"H"' is applied to pin INTO of the microprocessor, switch-
ing the following pins to the functions indicated:
PO3>SI _ : Serial data input pin
PO2—>SO_: Serial data output pin
P01 > SCK : Serial clock input/output pin
Fig. 15 Internal configuration of KRR-C0071 ladder resistance network
(Control unit 1C4)
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