ipLDK-60 SERVICE MANUAL
DIGITAL KEY TELEPHONE SYSTEM
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requiring DTMF monitoring are connected via a system “B” channel to one of 15 DTMF receiver channels in ACT2. And
the CPU on the MBU identifies which digit is generated from Single Line Telephone (SLT).
2) DTMF Tone Generation
With call processing tones, the system generates DTMF tones from digitally stored tones in ACT2 as a Look-up table.
DTMF tones in digital PCM form are injected onto the receive highway at the proper time slots by a digital summation
technique and digital gain modified by the Tone Generation block in ACT2 device on the MBU board. More about the
digital summation and gain process are discussed in section 2.4.3. Conferencing.
C. Real Time Clock
The system maintains its own real time with a real time clock circuit. The day, date and time are stored in the Device
retained in the system by the on-board lithium battery on the MBU. The clock is used for many system features such as
LCD time & date display, SMDR time & date printout, the wake-up call feature, etc.
D. System Information input/output (I/O)
The system can communicate detailed call records, customer database changes and diagnostic routines through multi-
purpose hardware I/O ports on the system MBU. A channel Universal Asynchronous Receive /Transmit (UART) device
is used to provide access to system terminal programming and diagnostic routines. The UART is directly connected to
I/O port of the MBU microprocessor. With the UART, terminal programming and system SMDR printout can be
accomplished simultaneously. The system customer database programming routines are directed by the system generic
software allowing only one communication port to access customer database programming at a time.
1) RS-232C
Communication
ipLDK-60 system provides a port of serial communication standard, RS-232C that is implemented by the first UART of
CPU. It provides asynchronous serial communications up to 19200 baud rates. A log-on procedure is used to enter the
system terminal programming mode and ASCII characters and control codes are used to modify the customer database.
The 9 pin RS-232C port is configured as Data Communication Equipment (DCE). Data is transmitted on pin 2 and
received on pin 3. Hardware flow control is supported with a Clear To Send function on pin 7. The system will halt
transmission of data when this signal is asserted by the connected equipment.
2) Modem
Communication
The optionally equipped modem unit functions on the second UART of main CPU (S3C4530A). Interface connectors on
the MBU allow the Modem unit to be installed as an option on the MBU. The modem will answer incoming line ringing to
the specified CO line with modem carrier tone. Modem communications will support up to 33k baud rates.
E. Digital Voice Announcement
The system optionally provides digitized voice announcements for system and station features. When the Voice Mail
Interface Unit (VMIU) is installed on MBU, features supported to the VMIU are provided with pre-recorded system voice
announcements, customized hunt group announcements and customized user voice announcements. The VMIU
provides 4 channels of access to voice announcements. All kinds of voice messages are stored digitally on NAND flash
memory and related information for voice are stored on RAM that is retained during power failure with a lithium battery
on MBU. When commanded by the MBU, the appropriate digitized voice announcement is converted from compressed
digital format to a PCM digital signal and placed on a receive “B” channel. The requesting station or system port is then
commanded to monitor that channel. System software control terminates the voice announcement and frees-up the
channel on the VMIU when the announcement is completed. When storing a customized voice announcement, the
