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– 5 –

The terminal for the earlier mentioned optional TC is of the 5-pin type used for system cables, etc. The serial data of the SDA terminal uses

the same signal format as CONTROL I.

Table 1-2. Function of Optional TC Terminals

Serial data input/output terminal
Normal:H, when the microprocessor is abnormal:L
Grounding terminal
+5V terminal
Serial clock input/output

No

I/O

Terminal Name

Function

1
2
3
4
5

I/O
I/O

–
–

I/O

SDA
HELP
GND
VDD
SCL

– 6 –

The following describes the terminals of CONTROL I.

SDA (I2C serial data):1 pin
SCL (I2C serial clock):5 pin

In the communication between microprocessors inside the current system stereo, the DATA line is expanded to four lines based on the AU

BUS, and a 6-line Y BUS with additional CLK and BUSY lines is used as the internal bus. System stereos after DHC-MD555, DHC-MD777,
and JMD-7 however adopt the Phillips “I2C format” for the communication format of the internal bus.

The I2C format bus is able to send a higher volume of data than the conventional Y-BUS using two lines serial data (SDA) and serial

clocks (SCL) and at high speed. By performing this I2C bus using the system stereo terminal, high speed communication between the system
stereo internal microprocessor and microprocessor of external equipments is possible.

The microprocessor incorporated in the CAV-PX1 connection cable of the PC connection kit PCLK-PX1 and microprocessor incorpo-

rated in the transmitter receiver of the bi-directional remote control RM-IA10K communicate with the microprocessor of the system stereo
via the CONTROL I terminal.

The microprocessor of the optional cassette deck TC-PX100 and TC-SD1 communicates with the system stereo microprocessor via a

exclusive connector.

When the I2C bus inside the system stereo is connected to an external equipment using a connection cable, rounding of waveform occurs

from the effects of the stray capacitance of the cable. When the cable is longer and the stray capacitance increases, the rounding of the
waveform increases, and may disable communication of the I2C bus.

For this reason, I2C dedicated buffer ICs are used for both the system stereo and external equipment to prevent I2C bus effects even when

the cable is connected.

When the power of the system stereo is in the STAND BY state, all functions are stopped except for some microprocessor functions in

order to decrease the power consumption. In this sleep mode, no communication operations by the I2C bus communication terminals SDA
and SCL are possible.

In the sleep mode, as the power of the I2C buffer IC is also turned off, the internal I2C bus and buffer ICs are cut off by the MOS-FET

switch to prevent incorrect operations by the effects of the external equipment.

VDD:4 pin

+5V is supplied from the system stereo only when the system stereo is in the power ON state. No power will be supplied in the STAND

BY state.

The I2C buffer IC in the system stereo and I2C buffer IC of the external equipment operate with this power. It prevents from that the

communication becomes impossible after one power is turned off.

The connection cable CAV-PX1 of the PCLK-PX1 incorporates the internal I2C buffer IC, 12C-RS232C conversion microprocessor, and

RS232C driver IC. These IC powers are all supplied at +5V from the system stereo.

The main power supply of the RM-IA10K transmitter receiver is supplied by the AC adapter. Only the power of the I2C buffer IC is

supplied from the system stereo. Although the optional TC also has its own power supply, only the power of the I2C buffer IC is supplied
from the system stereo.

When the power of the system stereo is ON, if the power of the above external equipment is OFF, power is supplied from the system stereo

to the I2C buffer IC in the external equipment. But, this power is cut by the MOS-FET SW between the I2C buffer IC and the microprocessors
of external equipment, and therefore has no effect on the I2C bus of the system stereo.

The power of the connection CAV-50C of the MDS-PC1 and PCLK-MD1 using the CONTROL-A1 terminal is created from the RS232C

signal of the PC and is not supplied from the component stereo.

– 7 –

POWER ON:6 pin
Input port for turning on the power of the system stereo from an external equipment when the system stereo is in the STAND BY state. It

is connected to the main microprocessor (microprocessor for controlling the power supply)of the system stereo.

The POWER input terminal of the main microprocessor is pulled up to H by the VDD. When the power on signal (L) from an external

equipment is input, the unit sets into the power on state.

Excessive noise may be output when the external equipment is turned on, etc. To prevent the power from turning on due to incorrect

operations by noises, the following POWER ON signal format is used.

Power on :  L (100ms)  

n  H (100ms)  n  L (100ms)

NC (OPEN):2 pin
Connected to nothing.

VDD:3 pin
GND terminal where current supplied from the +5V power is returned.

FRAME GND:8 pin
Shield part of the MINIDIN cable. Same as GND.

Sets to L when data communication errors of the I2C bus are generated and retransmission is requested. Errors are usually not generated.

– 8 –

The liquid crystal remote controller of the MD Walkman receives the liquid crystal display data output from the MD Walkman and

displays the name of the disc played, name of the track played, etc. The MD WALKMAN LINK function uses the audio output and liquid
crystal display output to the liquid crystal remote control to perform analog dubbing.

When the MD Walkman and system components such as DHC-MD555 are connected using the link cable (MDLK-PX1) for MD Walkman,

analog synchro recording and automatic track number setting can be performed using the headphone signal output from the MD Walkman.

Using the liquid crystal display data output from the MD Walkman, disc names and track names can be edited.

The MD WALKMAN LINK function is a one-directional dubbing function for dubbing from the MD Walkman to the system component.

Connect the side of the MD link cable with the cylindrical ferrite core to the MD Walkman. If the opposite side is connected, errors may

occur during data transmission.

Settings for the MD Walkman to display the progress time and track number must be performed using the DISPLAY button of the MD

Walkman.

The MD Walkman link function requires to set the recording level due to the use of the headphone outputs of the MD Walkman for the

recording source. If this setting is not performed, the sound may become small or distorted.

After recording, lower the volume of the MD Walkman.

Required settings
• Turn OFF the MEGA BASS (emphasis of bass sounds) switch of the MD Walkman.
• After turning ON the AVLS (volume limit) switch of the MD Walkman, set the volume of the remote control to maximum.
• Set FUNCTION (source) of the system stereo to “MD WALKMAN”.