User`s manual
Table Of Contents
- 1. Introduction
- 2. Getting Started
- Powering on the W406-LX
- Connecting the W406-LX to a PC
- Configuring the Ethernet Interface
- USB Port for Expansion
- SD Socket for Storage Expansion
- Setting Up the Wireless Module
- Configuring the SIM Card
- Entering the PIN Code
- Verifying the SIM Card Status
- Enabling or Disabling the PIN Code Authentication
- Changing the PIN Code
- Unlocking the SIM Card
- Connecting to the Internet
- Reconnecting to the Internet
- Disconnecting from the Internet
- Detecting an Internet Connection Error
- Sending and Reading an SMS Message
- Deleting an SMS Message
- Test Program—Developing Hello.c
- 3. Managing Embedded Linux
- 4. Managing Communications
- 5. Development Tool Chains
- 6. Programmer’s Guide
- 7. Software Lock
- A. System Commands
W406-LX User’s Manual Introduction
1-3
The W406-LX’s built-in Flash ROM is partitioned into Boot Loader, Linux Kernel, Root File
System, and User directory partitions.
In order to prevent user applications from crashing the Root File System, the W406-LX uses a
specially designed Root File System with Protected Configuration for emergency use. This
Root File System comes with serial and Ethernet communication capability for users to load the
Factory Default Image file. The user directory saves the user’s settings and application.
To improve system reliability, the W406-LX has a built-in mechanism that prevents the system
from crashing. When the Linux kernel boots up, the kernel will mount the root file system for
read-only, and then enable services and daemons. During this time, the kernel will start searching
for system configuration parameters via rc or inittab.
Normally, the kernel uses the Root File System to boot up the system. The Root File System is
protected, and cannot be changed by the user. This type of setup creates a “safe” zone.
For more information about the memory map and programming, refer to Chapter 6, Programmer’s
Guide.
Journaling Flash File System (JFFS2)
The Root File System and User directory in the flash memory is formatted with the Journaling
Flash File System (JFFS2). The formatting process places a compressed file system in the flash
memory. This operation is transparent to the user.
The Journaling Flash File System (JFFS2), which was developed by Axis Communications in
Sweden, puts a file system directly on the flash, instead of emulating a block device. It is designed
for use on flash-ROM chips and recognizes the special write requirements of a flash-ROM chip.
JFFS2 implements wear-leveling to extend the life of the flash disk, and stores the flash directory
structure in the RAM. A log-structured file system is maintained at all times. The system is always
consistent, even if it encounters crashes or improper power-downs, and does not require fsck (file
system check) on boot-up.
JFFS2 is the newest version of JFFS. It provides improved wear-leveling and garbage-collection
performance, improved RAM footprint and response to system-memory pressure, improved
concurrency and support for suspending flash erases, marking of bad sectors with continued use of
the remaining good sectors (enhancing the write-life of the devices), native data compression
inside the file system design, and support for hard links.
The key features of JFFS2 are:
y Targets the Flash ROM Directly
y Robustness
y Consistency across power failures
y No integrity scan (fsck) is required at boot time after normal or abnormal shutdown
y Explicit wear leveling
y Transparent compression