Sony Ericsson Embedded Applications Montage- und Bedienungsanleitung

Application Note

Embedded Applications

Using the on board TCP/IP stack

First edition (September 2004)

Sony Ericsson Mobile Communications. publishes this manual without

making any warranty as to the content contained herein. Further Sony

Ericsson Mobile Communications. reserves the right to make modifications,

additions and deletions to this manual due to typographical errors, inaccurate

information, or improvements to programs and/or equipment at any time and

without notice. Such changes will, nevertheless be incorporated into new

editions of this manual.

EMBEDDED APPLICATIONS FCT

Contents

Contents.....................................................................................................3

1Introduction ........................................................................................4

2Using the Embedded Application TCP/IP Functions for Data

Exchange....................................................................................................5

2.1 Overview of Embedded Applications TCP/IP ............................................5

2.2 Basic Usage of TCP/IP Features...............................................................6

2.2.1 Protocols........................................................................................6

2.2.2 GPRS Transport for IP...................................................................6

2.2.3 Flow of TCP/IP Operations in a Script ...........................................6

2.2.4 TCP Connect Operations...............................................................7

2.2.5 Testing Communications over TCP/IP...........................................8

2.3 General Restrictions ..................................................................................8

2.4 Resource Restrictions ...............................................................................8

2.4.1 Packet Buffers ...............................................................................8

2.4.2 IP Fragmentation ...........................................................................9

2.4.3 Performance ..................................................................................9

2.5 UDP Example Script {UDP_transfer.sc} ..................................................10

2.6 TCP Example Script {TCP_transfer.sc} ...................................................12

2.7 TCP Send Function Script {TCP_send.sc} ..............................................14

2.8 Host Name Resolution.............................................................................15

2.9 IP Status Flags and Bytes .......................................................................15

2.10 Advanced Technical Details ....................................................................16

2.10.1 Time-to-Live (TTL) .......................................................................16

2.10.2 DNS Name Caching Period .........................................................16

LZT 123 8019 R1A 3

EMBEDDED APPLICATIONS FCT

1 Introduction

This application note describes the use of the TCP/IP sack

that is resident on the module within the embedded

applications environment.

LZT 123 8019 R1A 4

EMBEDDED APPLICATIONS FCT

2 Using the Embedded Application TCP/IP

Functions for Data Exchange

2.1 Overview of Embedded Applications TCP/IP

The TCP/IP features provided by the embedded

application functions of the radio device are intended to

provide a subset of the features normally available at the

socket level when using a conventional TCP/IP stack, with

some simplification and customization based on the

specific features of the radio device.

The features allow the application-writer to create and

destroy UDP and TCP sockets, to control underlying

GPRS PDP contexts, to transfer data to and from the radio

device, and to interrogate IP status information about the

active link.

The socket interface is provided by a series of functions

outlined below:

pdpa() Activate and deactivate a PDP context for TCP/IP over GPRS

ipo() Open a UDP or TCP socket for data transfer

ipc() Close a previously opened UDP or TCP socket

tcpc() Connect to a TCP server specifying IP address and port

tcps() Send data over a previously connected TCP socket

tcpr() Receive data over a previously connected TCP socket

udps() Send data over a UDP socket

udpr() Receive data over a UDP socket

ipi() Obtain IP-related information associated with the GPRS link

iprh() Perform a text-to-IP-address hostname resolution

For full details of these functions, their parameters and

possible return values, refer to the syntax data in the

M2mpower IDE Help files.

The majority of the functions, with the exception of the

tcpc() function, will only return once the requested

operation is complete. More detail regarding tcpc() is

provided in later sections of this application note.

LZT 123 8019 R1A 5

EMBEDDED APPLICATIONS FCT

2.2 Basic Usage of TCP/IP Features

2.2.1 Protocols

The radio device embedded application functions provide

support for the IP, UDP and TCP protocols. The user has

no direct control over the IP layer (for instance a raw

sockets interface is not provided), it is simply used as a

transport by the higher-level protocols.

UDP provides for fast connectionless, less reliable

communications between the radio device and remote

hosts; TCP provides slower but reliable, connection-

oriented communications, with flow-control, sequence

checking and reordering.

Whilst the lower-level stack provides support for ICMP

(Internet Control Messaging Protocol) features, and ICMP

packets influence the operation and performance of the

lower-level TCP/IP stack, the application-writer has no

direct access to any ICMP features.

2.2.2 GPRS Transport for IP

In order to use the embedded TCP/IP functions, a GPRS

PDP context must be activated first, to provide the

underlying IP transport. This should be done using the

pdpa() function, not by using direct AT dial commands.

The embedded applications TCP/IP cannot properly make

use of a PDP context that has been created using the ATD

command.

In order to activate a PDP context, the details associated

with the context (such as APN) must have been previously

established. This is achieved using the AT+CGDCONT

command. Use of AT commands to define PDP contexts

alongside TCP/IP functions is normal; it is the PDP

activation and deactivation that should not be performed

using AT commands.

Once the PDP context is active, a socket can be created

to enable bi-directional communications using TCP or

UDP.

2.2.3 Flow of TCP/IP Operations in a Script

The basic flow of the TCP/IP operations within a script will

normally take the following form:

LZT 123 8019 R1A 6

EMBEDDED APPLICATIONS FCT

Define an appropriate PDP context according to

Service Provider data

Activate the required PDP context

Create a socket

For TCP only, perform a Connect to a remote host

Send data or status information over the socket to a

remote host

Receive data or status information over the socket

from a remote host

Repeat steps 5 and 6 for as long as the connection is

required

Once communications are complete, close the socket

Repeat steps 3 to 8 for communications with different

remote hosts

Deactivate the PDP context

2.2.4 TCP Connect Operations

A TCP connect operation can take quite a long time to

complete, depending upon the link performance, lost

packets etc. Therefore the tcpc() function has been made

non-blocking to avoid stalling the script for long periods.

A call to tcpc() will initiate a connection but return

immediately, leaving the lower level system to connect as

responses are received. If no connection is achieved

within a timeout of approximately 75 seconds, an

indication of the failure at the script level will occur when a

send or receive is attempted on a socket for which the

connection is not yet active. This means that the

application-writer should do one of two things to ensure

that send and receive operations do not fail because a

connection has not yet completed, either

Before a send or receive operation check the

connection status by using the

gtb(TCP_STATUS_BYTE) function and checking

against TCP_CONNECTED (where

LZT 123 8019 R1A 7

EMBEDDED APPLICATIONS FCT

TCP_STATUS_BYTE = 14, TCP_CONNECTED = 2),

2 Check the result code from a send or receive operation

and if the code indicates CONNECTING (1) then retry

the operation, with appropriate timeouts applied.

2.2.5 Testing Communications over TCP/IP

The TCP/IP stack supports ICMP operations, such as ping

responses these influence the operation of the low-level

stack. However, the application-writer cannot perform ping

tests from within a script. The only method for testing

whether a remote site can be accessed is to attempt either

a UDP or TCP operation to the host.

2.3 General Restrictions

The TCP/IP interface supports a single socket meaning

that the embedded application can have only a single

active socket at any one time. Use of, for instance, a UDP

socket and a TCP socket in the same application requires

that the script closes one socket before attempting to open

or re-open another. For the majority of applications, the

module is only ever transferring data over a single socket,

so the restriction will not cause problems.

2.4 Resource Restrictions

2.4.1 Packet Buffers

The TCP/IP system supports a maximum of six

simultaneous packets of size 1-1536 bytes, plus an

additional two packets of size 1537-3100 bytes. If, having

assigned all of these buffers, additional packets are

received, or queued for transmit, the packets will be

silently dropped. The packet buffers are shared with the

lower-level GPRS system, hence the limits apply to the

total data being buffered within GPRS and TCP/IP

software layers.

Due to the buffer considerations, it is strongly

recommended to use TCP rather than UDP to transfer

larger volumes of data, or any quantity of critical data. The

likelihood of packet loss within the radio device when

using UDP is quite high, even for infrequent ‘bursts’ of

data transfer.

LZT 123 8019 R1A 8

EMBEDDED APPLICATIONS FCT

2.4.2 IP Fragmentation

The radio device stack supports IP fragmentation and will

successfully reconstruct fragmented packets provided:

No individual fragment exceeds the maximum packet

size of 3100 bytes

The total reconstructed size of the fragmented packet

does not exceed 3100 bytes

The internal packet buffers are not exhausted during

the period that the fragments are being received.

The TCP/IP stack will, especially during busy periods,

buffer and consolidate transmit data. This will sometimes

result in data being sent from the radio device in larger

units than submitted by the application. However, the

largest sent-packet size will not exceed the reported

Maximum Transmission Unit (MTU) of the underlying link.

2.4.3 Performance

Both the GSM module and the underlying GPRS transport

infrastructure impose performance restrictions that can

influence the effective IP performance of the application

such that throughput can not be guaranteed.

LZT 123 8019 R1A 9

EMBEDDED APPLICATIONS FCT

2.5 UDP Example Script {UDP_transfer.sc}

A simple example of a UDP data transfer script is listed

below. The script creates a UDP socket, sends some start

data and then sits in a receive loop until a ‘$’ character is

received, after which it closes the socket and exits.

int Err;

int Port = 3000;

int Address = 0x0A8402A3; /* 10.132.2.163 */

int RXTX_SIZE = 1000;

char RxTxBuf[RXTX_SIZE] = “Starting! “;

char Complete = FALSE;

int APPS_IP_ERROR_TRIGGER = 36;

int APPS_IP_ERROR_STATUSBYTE = 13;

int APPS_IP_DATA_RECVD = 13;

int APPS_IP_TCPSTATUS_BYTE = 14;

/* Reset the IP error flag by reading it */

gtf( APPS_IP_ERROR_TRIGGER );

Err = pdpa( 1, 1 );

prtf( "\n PDP activate result = %d\n", Err );

if ( Err == 0 )

{

Val = ipi( 0 );

prtf(" IP Address = %x", Val );

Val = ipi( 1 );

prtf( "\n DNS 1 = %x", Val );

Val = ipi( 2 );

prtf( "\n DNS 2 = %x\n", Val );

}

else

{

prtf( "\n PDP activation failed!\n" );

return;

}

Err = ipo( 0, &SckNum );

if( Err != 0 )

{

prtf( “ \n UDP Socket open failed!\n” );

}

else

{

int len;

prtf( "\n UDP Socket Opened!\n" );

prtf( "\n Sending start data...\n" );

len = 10;

Err = udps( SckNum, Port, Address, RxTxBuf, len );

while( !Complete && (gtb( APPS_IP_ERROR_STATUSBYTE ) == 0) )

{

/* Receive some data */

if( gtf( APPS_IP_DATA_RECVD ) )

{

prtf( "\n IP DATA RECVD" );

len = RXTX_SIZE;

Err = udpr( SckNum, &Port, &Address, RxTxBuf, RXTX_SIZE, &len );

if( Err != 0 )

{

prtf( "\n UDP receive error!\n" );

}

LZT 123 8019 R1A 10

Inhaltsverzeichnis

Andere Sony Ericsson Software Handbücher

Sony Ericsson

Sony Ericsson SplashPhoto 4.0 Bedienungsanleitung

Sony Ericsson

Sony Ericsson K500i Betriebsanleitung

Sony Ericsson

Sony Ericsson GR47 Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson CM52 Bedienungsanleitung

Sony Ericsson

Sony Ericsson RS232 interface for GT47 embedded apps UART Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson GPRS and TCP-IP with the SEM GSM modules Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson RC function Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson GT47 Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson RC function Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson Dual SIM connection Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson DCU-10 Bedienungsanleitung

Sony Ericsson

Sony Ericsson Fixed Cellular Telephone Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson Controller Mode Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson Automatic meter reading with M bus Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson Label Make II Merkblatt

Sony Ericsson

Sony Ericsson Simple Telemetry Application Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson Construction of SMS PDU's Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson Speakerphone/car kit hands free design Montage- und Bedienungsanleitung

Sony Ericsson

Sony Ericsson GM47 Montage- und Bedienungsanleitung

Beliebte Software Handbücher anderer Marken

COMPRO

COMPRO COMPROFM Bedienungsanleitung

Muratec

Muratec OFFICEBRIDGE ONLINE Bedienungsanleitung

Oracle

Oracle Contact Center Anywhere 8.1 Bedienungsanleitung

Adobe

Adobe 65007312 - Photoshop Lightroom Handbuch

Avaya

Avaya NULL One-X for RIM Blackberry Bedienungsanleitung

HP ProLiant BL420c Bedienungsanleitung

PS Audio

PS Audio PowerPlay Betriebsanleitung

Brady

Brady LOCKOUT PRO 3.0 Service-Handbuch

Avaya

Avaya Interaction Center Bedienungsanleitung

Texas Instruments

Texas Instruments TI-83 Plus Silver Edition Handbuch

Novell

Novell GROUPWISE 8 - INTERNET AGENT Bedienungsanleitung

Oracle

Oracle Application 9i Bedienungsanleitung

Acer

Acer RDM Bedienungsanleitung

Canon

Canon Vixia HF21 Bedienungsanleitung

Canon

Canon ZR950 Bedienungsanleitung

Samsung

Samsung Auto Backup Bedienungsanleitung

Polycom

Polycom Vortex EF2201 Montage- und Bedienungsanleitung

Brocade Communications Systems

Brocade Communications Systems Brocade 8/12c Bedienungsanleitung