User guide

Atmel AVR2054: Serial Bootloader User Guide [APPLICATION NOTE]
8390D−WIRELESS−03/2015
3
1. Overview
The serial bootloader allows loading of firmware images to an MCU over the serial connection. It is intended for use
with Atmel
®
wireless stacks, such as IEEE
®
802.15.4 MAC [1] , RF4CE [2], BitCloud
®
[3] and LwMesh [5], but can also
be used with non-wireless applications. The package content is given in Section 1.3 while Chapter 2 gives brief starting
instructions on how to use the serial bootloader tool.
The concept of firmware programming with the serial bootloader is shown on Figure 1-1. The embedded bootloader
preprogrammed to the MCU receives an application image over serial interfrace and writes it to the internal MCU flash.
An application firmware image should be loaded in the Motorola S-record hexadecimal format (SREC) and is expected
to be transferred by a host device. The host may be a PC or another MCU/MPU. It should be connected to the target
MCU via supported serial interface and deliver the application image following the specific protocol.
Figure 1-1. General approach for using serial bootloader for MCU programming.
Host (PC/MCU)
Serial
connection
Bootloader host
application
.srec
image
Embedded
bootloader
Application
Image
MCU
Embedded bootloader also supports some stack-specific functionality required to perform firmware Over-The-Air
Upgrade (OTAU) procedure in ZigBee or RF4CE networks. Sections 3.7 and 3.8 provide more information on this topic.
Chapter 3 describes in details how the embedded bootloader works on different serial interfaces as well as how to
configure and compile its source code.
For convenience the Serial Bootloader package includes pre-compiled images of the embedded bootloader images in
different configurations. It also contains Atmel implementation of a PC host application - Bootloader PC tool that can be
operated as a GUI application or as a command line tool (see Chapter 4 for instructions how to use it).
The Bootloader PC tool may also be used to initiate an Over-the-Air Upgrade (OTAU) of a ZigBee
®
network by
transferring a firmware image to the OTAU server device connected to the PC via a serial interface. See Section 3.7 as
well as [8] for more details.
1.2 Supported platforms and interfaces
Embedded bootloader is supported on a set of Atmel microcontrollers shown in Table 1-1. It is implemented to be board-
independent and works on Atmel development boards as well as custom boards. The PC tool however requires
COM/USB enumerated ports and might not support board-specific functionalities.
Embedded bootloader can work with several different serial interfaces simultaneously as listed in the table Table 1-1
(except of TWI that needs to be used alone only). More details on the interface configurations are given in Section 2.1).