User's Manual

Iridium Communications, Inc. Information Contained in this Guide
Iridium Core 9523/9523N Product Developer’s Guide is Subject to Change Without Notice
Revision 7.2 DRAFT4
Iridium Communications, Inc. Distribution of Guide Restricted
Proprietary & Confidential Information Page 31 of 34 to Product Developers
Only
3.3.3 11Hz Signal for Manufacturing and Regulatory Testing
An external ‘frame tick’ signal needs to be passed to the Iridium Core 9523/9523N during regulatory radio
testing of the host system, and possibly also during manufacturing testing. This frame signal has a period
of 90ms (11.1Hz) and is fed to the Iridium Core 9523/9523N using the CODEC_PCMOUT PCM data
input.
The frame tick signal can have any mark-space ratio but must be externally synchronized to the Iridium
Core 9523/9523N’s internal clock. This is most easily achieved by double buffering the signal through two
D-type latches clocked by CODEC_PCMCLK.
3.4 DPL port
The DPL port is a three-wire asynchronous serial port. It carries 8-bit, no parity data at 115,200 baud.
The DPL port enables peripherals such as handsets and SIM card readers to be interfaced to the Iridium
Core 9523/9523N. The interface utilizes an Iridium proprietary communication bus not detailed in this
document. Details can be made available after appropriate Non-Disclosure and/or License Agreements
are executed.
The serial data signals use standard 3.3V signals with conventional polarity. If desired, an external RS232
level converter could be fitted to the FA board to extend range.
3.5 Data/Fax port
The asynchronous serial data/fax interface is comprised of eight standard RS232 data (8-bit, no parity),
control, and status signals plus a ground level signal reference. This interface allows the FA to utilize the
Iridium Core 9523/9523N’s modem functionality via AT command control. With respect to this interface,
the Iridium Core 9523/9523N behaves as a DCE (Data Communication Equipment), and the FA behaves
as a DTE (Data Terminal Equipment).
The data/fax interface supports 3.3V / LVTTL levels. If RS-232 voltage levels are needed, the FA must
include an LVTTL/RS-232 level shifter.
A 3-wire RS232 Data minimal interface may also be implemented; however the 9-wire interface offers
better control and is the recommended implementation.
Autobaud is enabled by default. Autobaud will occur on the following characters: ‘a’, ‘A’, or CR (carriage
return). Autobaud will also occur on the escape sequence character, provided this is an odd number
character. Normally this is set to ‘+’ in register S2.
See the ISU AT Command Reference for further information on the data/fax interface.
3.6 SIM interface
The Iridium Core 9523/9523N needs an external Iridium SIM card and socket to be connected to its SIM
interface. The signals operate at 3.3V logic levels, so an external SIM level converter such as the
ONSemi NCN4555 must be connected between the Iridium Core 9523/9523N and the SIM
connector/socket to allow 3V or 1.8V SIM cards to be used.
An external SIM card reader may also be interfaced as a peripheral to the Iridium Core 9523/9523N via
the DPL interface. A SIM card in the external reader will take precedence over the SIM chip connected to
the SIM interface when both are present.