Laird WB45NBT
Reference Guide
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Flash Programming Using the Atmel SAM-BA Utility
This section describes the process of programming the OS images into a WB45NBT module. SAM-BA (Smart ARM
Microcontroller Boot Assistant) is a programming utility provided by Atmel. This utility can program flash memory
that is attached to an AT91 microcontroller through either a serial port or through a USB port. It is highly
recommended to avoid the serial port method because it is too slow for transferring large OS images.
Binary Image Description
The following are the four binary images that are programmed into the WB45NBT module:
at91bs.bin --- Bootstrap loader
u-boot.bin --- U-Boot boot loader
kernel.bin --- Linux kernel
rootfs.bin --- File system image
These images are programmed into four specific locations in the 128 MB flash memory of the WB45NBT module.
Table 1
describes the locations for each binary image within flash memory. Pre-compiled binary images are available
for download from Laird.
Preparing the Laird WB45NBT for Programming
If the flash memory has been previously programmed, then it is necessary to temporarily disable the flash memory
by shorting out the chip-select to the flash memory chip. This can be done by shorting TP23 and TP24 (
Figure 1
)
using a pair of tweezers before power is applied and until two or three seconds after power up.
Figure 1: TP23 and TP24
By disabling the flash in this way, the AT91 processor executes its own internal ROM Boot Loader during the
application of power. The ROM Boot Loader must be running in order to attach to the WB45NBT using SAM-BA.
Roughly three seconds after power is applied, the short across R16 may be removed.
Installing the Atmel AT91 Driver
If this is the first time you are programming the board you will need to install the AT91 USB CDC driver for SAM-BA
to communicate with it.
To install the driver, follow these steps:
1.
Prepare the board for programming by shorting R16 on power up. See:
Preparing the Laird WB45NBT for
Programming
section.
