User's Manual

7/21
P1_6
I/O Pin header
GND
P1_7
I/O Pin header
GND
P2_0
Not connected
GND
P2_1
Debug data
Debug data
P2_2
Debug clock
Debug clock
P2_3
Not connected
GND
P2_4
Not connected
GND
Table 1: NANO USB and standard USB pin assignments
The debug interface on the NANO USB stick is accessible on test points between the USB connector
pins but these test points are small and difficult to access. Hence it is recommended to use the USB
bootloader code programmed into the device for loading application code onto the device.
All unused I/Os should be configured as input pull-down at the beginning of your application to reduce
current consumption.
4 NANO USB Stick Serial Boot Loader
This section will guide you through the steps needed to build a Serial Boot Loader (SBL) for a Z-stack
and for an RF4CE application and will explain you how to modify such an application to be compatible
with the SBL. The SBL is provided as a value-enhancing sample solution that enables the updating of
code in devices without the cost of maintaining any download-related code in the user application
other than ensuring a compatible flash memory mapping of the final output. SBL is effected as a
managed client-server mechanism which requires a serial master to drive the process (i.e. a PC GUI
application with access to the serial connection to the CC2531.)
Since the NANO USB stick has no human interface such as keys, the boot loader will always
automatically start before the application, wait for a potential application downloading during ~15sec,
and then automatically jump to the application if any valid image is already loaded in flash. If not, it will
wait for an application downloading forever.
Therefore, when the SBL will be loaded into flash memory, each time you connect your NANO USB
stick into a USB port you will have around 15 seconds to download your new application. Then the
SBL will jump to the existing application and you won’t be able to download your new application
anymore.
The following sections will walk you through the steps needed to build and download the SBL, then
build and download an SBL compatible application using IAR to finally load your application on the
NANO USB stick using SBDemo tool.
4.1 Software required
File name
Description
Link
Bootloader_xxx.hex
Bootloader hex file
Wiki ZIP
archive : File:NANO-
USB package.zip
SBDemo
Serial Bootloader PC interface
demo application, used to load
binary files with the bootloader
znp.bat, znp.js, sim2bin.exe for a Z-
stack application
pp_cc2531f256sb.bat, oadbbin.exe
for a RemoTI stack application
scripts and executable files
performing file conversion