Laird WB45NBT
Reference Guide
Embedded Wireless Solutions Support Center:
http://ews-support.lairdtech.com
www.lairdtech.com/wi-fi
5
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S
OFTWARE
The WB45NBT has 128 MB of NAND flash memory that is divided into partitions (see
Table 1
). It uses 4-bit ECC in a
64 bit OOB area in each sector.
Table 1: Flash memory partitions
Image
Partition
Start
End
Size
MTD
Type
bootstrap.bin
at91bs
0x00000000
0x0001FFFF
128 KB
/dev/mtd0
Raw
binary
u-boot.bin
u-boot
0x00020000
0x0009FFFF
512 KB
/dev/mtd1
Raw binary
-
u-boot-env
0x000A0000
0x000BFFFF
128 KB
/dev/mtd2
U-boot env
-
redund-env
0x000C0000
0x000DFFFF
128 KB
/dev/mtd3
U-boot backup env
kernel.bin
kernel-a
0x000E0000
0x0035FFFF
2.5 MB
/dev/mtd4
Kernel image
kernel.bin
kernel-b
0x00360000
0x005DFFFF
2.5 MB
/dev/mtd5
Kernel image
rootfs.ubi
rootfs-a
0x005E0000
0x02BDFFFF
38 MB
/dev/mtd6
UBI
rootfs.ubi
rootfs-b
0x02BE0000
0x051DFFFF
38 MB
/dev/mtd7
UBI
N/A
user
0x051E0000
0x07EFFFFF
46 MB
/dev/mtd8
Raw
N/A
logs
0x07F00000
0x07F7FFFF
512 KB
/dev/mtd9
Raw
There are four basic types of binary images that can be programmed into the flash memory:
Bootstrap loader
U-boot boot loader
Linux kernel
Root filesystem
The flash partition layout allows for two kernel images (kernel-a and kernel-b), as well as two file system images
(rootfs-a and rootfs-b). This allows an update to an alternate image without disturbing the currently running system.
Additionally, if something goes awry with the newly updated image, the original image is still available. The update
program is intelligent enough to program the correct partition (the one which is not currently being run).
The filesystem is stored using a format called Unsorted Block Images (UBI). This is a filesystem that lies on top of the
Memory Technology Device (MTD) layer. The MTD layer handles bad block mapping. When a bad block is
encountered, it is simply skipped and not used. As new bad blocks occur, they are marked as such and handled
properly between the MTD and UBI file system. The UBIFS handles wear-leveling.
WB45NBT Usage
One of the main applications of the WB is to enable Wi-Fi on your host device using one of the available interfaces of the
WB module. This section describes how to do this from a Linux or Windows host environment.
The quickest way to start controlling the WB is through the built-in Linux command line interface (CLI). The WB's CLI can
be accessed via the DEBUG UART (settings: 115200 8N1) or via Secure Shell (ssh). ssh logins can be accepted on Ethernet
(IP address assigned via DHCP – see your local DHCP server for address) or via USB Ethernet at IP address 192.168.3.1 port
22.
Once CLI access is available, configuration files on the device can be examined or modified.
C
ONFIGURING
IP
B
ASED
C
ONNECTIVITY
This section covers enabling your host device to communicate over Wi-Fi via the WB. The predominant use cases involve
using the WB as Ethernet to Wi-Fi, USB to Wi-Fi, or Serial PPP (RS232) to Wi-Fi peripherals. These use cases allow normal
IP network connectivity via the WB’s Wi-Fi interface. We’ll explain these use cases in this guide, but they aren’t the only
Commented [Sd1]:
As the serial instructions we give are PPP, we
should make this say "Serial-PPP (IP over RS-232)". It is possible to
do a straight RS-232 to WiFi bridging, but we don't explain that
here.
Commented [EB2R1]:
corrected
