Publication: Desarrollo y validación de un bootloader para aplicaciones de carga remota en entornos inalámbricos 802.15.4 y Zigbee
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2009-11
Defense date
2009-11-19
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Abstract
En el entorno hostil que suele representar una red inalámbrica de sensores (WSN): escenarios con alta densidad de dispositivos, equipos instalados en localizaciones de difícil acceso, comunicaciones de alta latencia sobre canales ruidosos con numerosas interferencias, etcétera, se hace necesario un mecanismo que posibilite la actualización del firmware de los componentes del sistema. De esta forma se podrían corregir errores de funcionamiento, modificar parámetros de comportamiento o simplemente añadir nuevas funcionalidades a los dispositivos de la red. La tecnología ZigBee, diseñada para la intercomunicación inalámbrica de dispositivos de reducida capacidad, tamaño, consumo y coste, se plantea como una de las más apropiadas para cubrir la mayoría de las necesidades demandadas en el campo de las redes de sensores. Sin embargo ni el estándar ZigBee, ni los perfiles superiores de aplicación que funcionan sobre él, especifican el procedimiento que han de seguir los dispositivos para actualizar su firmware, dejando que cada fabricante plantee su solución propietaria para los productos que introduce en el mercado. Así pues, el objetivo de este proyecto será desarrollar un cargador de arranque (bootloader) capaz de sustituir el firmware en ejecución en dispositivos ZigBee por otro que previamente una aplicación de carga remota ha recibido y almacenado en una memoria auxiliar. Para ello, será necesario familiarizarse previamente con el entorno de desarrollo (CodeWarrior) y las librerías IEEE 802.15.4 y ZigBee que suministra uno de los principales fabricantes de chips en la banda de frecuencias de 2,4GHz, Freescale, para una vez adquirida la capacidad de crear nuevas aplicaciones sobre ellas y entender el funcionamiento de las diferentes capas, programar el bootloader. Puesto que el procedimiento interno de actualización del firmware de un dispositivo ZigBee es muy dependiente de los componentes (chip, memoria, bus, etc.) que integre, será necesario estudiar también, a lo largo del desarrollo del proyecto, el caso concreto de los circuitos de los equipos que pretenden soportar esta aplicación. Finalmente, puesto que el bootloader debe ser capaz de actualizar equipos ZigBee de forma independiente del modo en que la nueva imagen llegue hasta la memoria auxiliar, será imprescindible elaborar una aplicación auxiliar (cargador RS232) capaz de transmitir el nuevo firmware al dispositivo. La elaboración de este cargador permitirá depurar y validar el funcionamiento del bootloader además de evaluar el formato óptimo de almacenamiento de la nueva imagen de firmware en la memoria auxiliar. ______________________________________________________________________________
In the hostile environment that is often a wireless sensor network (WSN), a great need of a system devices’ firmware updating mechanism rises up. This way, application bugs could be fixed, devices’ behaviour could be modified and new functionalities could be added. ZigBee technology is designed to grant wireless communications between small, low consumption & low cost devices, so it is probably the most appropriate standard to meet the needs demanded in the field of sensor networks. However, neither the ZigBee standard nor the application profiles specify how wireless devices can update their firmware. So each manufacturer will have to develop its proprietary solution for the devices that sells. Thus, the objective of this final thesis is to develop a boot loader capable of replacing the old firmware running on a ZigBee device by a new one previously stored in an auxiliary EEPROM by a remote programming application. To achieve this aim, the first step to be taken will be choosing a suitable ZigBee chip manufacturer (Freescale) and then becoming familiar with its development environment (CodeWarrior) and its IEEE 802.15.4/ZigBee libraries. Freescale is nowadays one of the leading ZigBee chip manufacturers working on the frequency band of 2.4 GHz and, at the time this thesis started, it was probably the best choice. Since the internal process of updating the firmware of a ZigBee device is highly dependent on its integrated components (chip, memory, bus, etc...) a deep study of chosen ZigBee device’s integrated circuits will have to be done next in order to successfully develop the bootloader. Finally, since the developed application should be able to update ZigBee devices in real time independently of the means the new image is stored in the EEPROM. To achieve that, it will be essential to develop next an auxiliary application (RS232 loader) capable of transmitting the new firmware to the device so the programmed bootloader could be debugged and validated. In addition to all this, the optimum format for storing the new firmware image in the auxiliary memory will be discussed.
In the hostile environment that is often a wireless sensor network (WSN), a great need of a system devices’ firmware updating mechanism rises up. This way, application bugs could be fixed, devices’ behaviour could be modified and new functionalities could be added. ZigBee technology is designed to grant wireless communications between small, low consumption & low cost devices, so it is probably the most appropriate standard to meet the needs demanded in the field of sensor networks. However, neither the ZigBee standard nor the application profiles specify how wireless devices can update their firmware. So each manufacturer will have to develop its proprietary solution for the devices that sells. Thus, the objective of this final thesis is to develop a boot loader capable of replacing the old firmware running on a ZigBee device by a new one previously stored in an auxiliary EEPROM by a remote programming application. To achieve this aim, the first step to be taken will be choosing a suitable ZigBee chip manufacturer (Freescale) and then becoming familiar with its development environment (CodeWarrior) and its IEEE 802.15.4/ZigBee libraries. Freescale is nowadays one of the leading ZigBee chip manufacturers working on the frequency band of 2.4 GHz and, at the time this thesis started, it was probably the best choice. Since the internal process of updating the firmware of a ZigBee device is highly dependent on its integrated components (chip, memory, bus, etc...) a deep study of chosen ZigBee device’s integrated circuits will have to be done next in order to successfully develop the bootloader. Finally, since the developed application should be able to update ZigBee devices in real time independently of the means the new image is stored in the EEPROM. To achieve that, it will be essential to develop next an auxiliary application (RS232 loader) capable of transmitting the new firmware to the device so the programmed bootloader could be debugged and validated. In addition to all this, the optimum format for storing the new firmware image in the auxiliary memory will be discussed.
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Redes de comunicación, Redes inalámbricas, Redes de sensores inalámbricas