Siemens Mux_guide_v06 Customer C, GSM engine

Multiplexer User's Guide

Confidential / Released

s

mo b i l e

Mux_guide_v06 Page 25 of 36 30.06.2004

4.3.1 Start-up procedure

The only approach to activate the multiplexer protocol is entering the appropriate AT

command AT+CMUX=0. This enables the multiplexer control channel. The next step is to set

up the multiplexer control channel as described in Chapter 4.3.2.

4.3.2 DLC establishment

The multiplexer control channel must be set up as the first channel followed by all other

DLCIs. To do so, a SABM frame (see Chapter 4.2.3) must be sent to the GSM engine.

The module responds either with a UA frame if the DLCI was set up, or with a DM frame if

the DLCI was not set up.

No provision is made for repeating the request if a response is not received.

The state machine requesting the multiplexer control channel DLCI = 0 is the "initiating

station", while the other is called the "responding station".

CustomerµCGSMengine

SABM: P = 1

Address Field = DLCI of channel to be established

UA: F = 1, DLCI is being established

DM: F = 1, not ready, DLCI is not established

Address Field = DLCI of requested channel

Figure 7: DLC establishment

4.3.3 Information transfer

A response is not essential for every command – for example, an unsolicited result code

does not require a response.

Customer

µC

(Initiator)

GSM engine

(Responder)

UIH: P = 0, C/R = 1

UIH: P = 0, C/R = 0

Figure 8: Information transfer

Contents

Main Users Guide Multiplexer User's Guide Multiplexer User's Guide Confidential / Released Mux_guide_v06 Page 2 of 36 30.06.2004 Contents Figures Tables 0 Document history 1 Introduction 1.1 Supported products and related documents 1.2 References 1.3 Term and abbreviations 2 Multiplexer protocol an overview 2.1 Product concept and architecture 2.2 Virtual channels and AT commands 3 Integrating multiplexer into the customer application 3.1 Characteristics 3.1.1 Basic requirements 3.1.2 Restrictions 3.1.3 Dependencies between multiplexer channels and restrictions of use 3.1.4 Functions without channel dependencies 3.1.5 Timing conditions 3.1.6 Operation of a second physical serial interface ASC1 (if applicable) 3.2 Multiplexer control and signaling lines 3.2.1 Flow control Page 3.2.2 Escape sequence 3.3 Power saving 3.4 Bandwidth of logical channels 4 Structure of the multiplexer protocol 4.1 Introduction of the multiplexer protocol 4.2 Data link layer 4.2.1 Flag sequence 4.2.2 Address field 4.2.3 Control field 4.2.4 Length indicator 4.2.5 Information field 4.2.6 Frame checking sequence field (FCS) 4.3 State diagrams Figure 4: Relationship between the customer C and the GSM engine C Customer C Master state machine GSM engine C Slave state machine Customer C GSM engine C Figure 5: MPI Startup, DLC establishment and information transfer Serial interface Customer C GSM engine C Serial i nterface 4.3.1 Start-up procedure 4.3.2 DLC establishment Customer C GSM engine 4.3.3 Information transfer Customer C (Initiator) GSM engine (Responder) Customer C GSM engine 4.3.5 Close-down procedure 4.3.6 Multiplexer control channel Information Field 4.3.7 Multiplexer close down (CLD) 4.3.8 Test command (Test) 4.3.9 Modem status command (MSC) Page 4.3.10 Power saving control (PSC) 4.3.11 Non-supported command response (NSC) Multiplexer User's Guide Confidential / Released 4.4 Example: Establishing logical channels without parameter negotiation Customer C Serial interface GSM engine C Figure 13: Establishing the multiplexer control channel and the logical channel 5 Multiplexer protocol version control 5.1 Introduction 5.2 Multiplexer protocol versions 5.3 Implementing version control 5.3.1 Troubleshooting 5.3.2 Coding of TestCommand message 5.3.3 Example of TestCommand message