- This is my English translated paper of the original Indonesian paper published at National Conference on Smart-Green Technology in Electrical and Information Systems (CSGTEIS), Bali, 14-15 November 2013.
- The copyright has been transferred to the Department of Electrical Engineering, Faculty of Engineering, Udayana University, and based on the agreement, the author is allowed to upload this article to blogs and websites on the to provide the link to the copyright owner's publication website, namely https://ojs.unud.ac.id/index.php/prosidingcsgteis2013/article/view/7259. This means that all of these writings are not licensed under creative commons but copyrighted © under Department of Electrical Engineering, Faculty of Engineering, Udayana University where other people must ask for permission from us for reposting.
- Authors: Fajar Purnama, I Made Oka Widyantara, dan Nyoman Putra Sastra.
Previously, wireless sensor network (WSN) Imote2 used the Intel Platform X, SOS, and TinyOS operating systems. Now Platform X and SOS are no longer being developed, so many researchers are using TinyOS. End users of TinyOS on the Imote2 platform encounter many limitations such as implementing complex routing. Therefore the Embedded Linux community develops embedded Linux for the Imote2 platform. This paper discusses in detail the steps to embed Linux on the target, namely the Imote2 platform WSN radio sensorboard device. Host is a Linux operating system. The developer includes 3 main components, namely the bootloader, Linux kernel, and filesystem. Embedding is done by flashing the JTAG interface using the OpenOCD software. After embedding, configuration is done on the target via serial connection. Configuration includes automatically enabling IP address, SSHD, and radio. Finally compared to the target performance using IEEE 802.11 WLAN and IEEE 802.15.4 ZigBee as transmission media. The result is that the use of IEEE 802.11 WLAN is more wasteful of memory and electricity.
Keywords: Wireless Sensor Network, Imote2, Embedded Linux, ZigBee, WLAN, JTAG, OpenOCD.
Overall this paper consists of 4 parts. The first part of "Introduction" provides a brief overview of wireless sensor networks (WSN), some of the research that has been done in the field of WSN, and what will be discussed in this paper. The second part "Intel Mote 2 (Imote2)" describes WSN devices with the Imote2 platform. In this section you can see the physical form of the tool and mention some of the operating systems that are implemented on this platform. In the third part "Embedded Linux Implementation", the steps for installing the Linux operating system on the Imote2 platform are written. The last part is "Conclusion".
WSN or better known as a wireless sensor network (WSN) is a sensor device that communicates wirelessly to each other. These devices are placed over large geographic areas and form a network of sensors. This WSN does not have to be connected to the Internet. The main task of this sensor is to collect information from the surrounding environment, after which it sends the information to the user's device via the sensor network. This tool has been applied in the fields of civil, medical, and many other fields .
The existence of WSN is based on many limitations, such as limited power and limited wireless channel capabilities. Therefore, these wireless sensors form a network called WSN. Apart from being necessary to strategically place sensors (overcoming coverage holes), efforts are also needed to save energy and time in providing continuous information because the resources on WSN are limited . An overview of the JSN can be seen in Figure 1.
In WSN there have been several previous studies such as research  which uses multiple WSN cameras to capture the same image. The device is placed in a different position but aimed at the same object. Combining images captured at different angles can improve image quality. At the end of the study, a form of WSN that works on this concept was proposed. The research  led to the modeling of low power consumption WSN cameras by determining image quality. This research concludes several points that need to be considered in the WSN camera modeling, namely (i) camera selection method (ii) image compression method and strategy (iii) image transmission method. But this paper will not discuss WSN in that scope.
Unlike  and  this research is about embedded Linux in WSN, as has been done by Researcher , , and . At  and , the performance of the Imote2 platform on their respective wireless sensor networks uses IEEE 802.15.4 Zigbee and IEEE 802.11 WLAN networks. While the embedded linux implementation model on WSN, these two studies use the same scheme, namely (i) connecting a multimedia WSN device to a computer (ii) installing a bootloader, Linux kernel and filesystem (iii) managing the internet protocol (IP) network and the secure shell daemon (SSHD) (iv) activate radio (v) measure memory consumption and power consumption.
After this is done, we can add some features, such as capturing images with the IMB400 camera sensor board which is visible at  and . However, this paper does not go that far, but discusses embedded Linux on the Imote2 platform radio sensorboard in detail.
Intel Mote 2 (Imote2)
Imote2 is a platform on the WSN device developed by Intel Research in the platform X research section. This device is built with low power consumption, with a PXA271 XScale CPU processor, and is integrated in IEEE 802.15.4 ZigBee . This processor (Intel Xscale processor PXA271) can operate at low voltages (0.85V) and frequencies of 13MHz to 104MHz. The frequency can be increased up to 416MHz by setting the voltage . In general, Imote2 consists of 4 parts as shown in Figure 2.
The PXA271 consists of 3 chips (i) the processor itself (ii) 32MB SDRAM (iii) 32MB flash. The radio used is the TI CC2420 which is based on IEEE 802.15.4 ZigBee, where devices with this standard at the PHY and MAC layers operate at low power and short-range radio, targeted for control and monitoring applications. The CC2420 also supports a 250kbps data rate with 16 channels on the 2.4GHz frequency .
Previously Imote2 worked on Intel Platform X. After Imote2 moved to Crossbow, Intel Platform X was no longer being developed because Crossbow released its own operating system. Operating systems mostly developed by communities such as SOS. However, SOS stopped being developed in 2008. Currently, what is still visible is TinyOS and Linux .
Prior to Embedded Linux, the operating system used on Imote2 was TinyOS. Most publications on the web use TinyOS such as , , and . Embedded Linux is now being developed because it finds limitations on TinyOS such as complex-routing in a WSN topology. The Embedded Linux community sees the Imote2 Embedded Linux operating system as a solution to overcome these limitations. However Embedded Linux in Imote2 is still new and under development .
Embedded Linux Implementation
The device used is the same as the ones used in [6-9] and [13-15], the Imote2 platform multimedia sensorboard radio has (i) 256KB SRAM memory (ii) 32MB flash (iii) 32MB SDRAM (iv) integrated radio with 802.15.4 (v) optional radio from SDIO and UART (vi) 2.4GHz antenna (vii) basic and advanced connectors such as 3xUART , I2C, 2xSPI, SDIO, I2S, AC97 audio, USB host, I/F camera, mini USB GPIO. The architecture of the device can be seen in Figure 3.
This section will discuss in more detail the technical details of embedding Linux on the target, namely the Imote2 platform multimedia radio sensorboard with the main source . Host is Linux OS. Linux distributions can be used anywhere, but the commands in this paper are based on Ubuntu or Debian. In brief, the stages can be seen in Fig. 4.
In "make menuconfig" it is configured as follows :
Then repeat the steps from compiling the Linux kernel and filesystem to flashing and configuration. In the research  using TL-WN321G (TP-LINK), the Linux driver version can be downloaded on the official site. The installation steps are as follows:
#********This file configures Wlan on Imote2**************
echo -n 1 > /sys/bus/usb/devices/1-1/bConfigurationValue
ifconfig rausb0 up
iwconfig rausb0 essid imote2
iwconfig rausb0 mode ad-hoc
ip link set rausb0 up
ifconfig rausb0 inet 192.168.1.2
ifconfig rausb0 netmask 255.255.255.0
ifconfig rausb0 gateway 192.168.1.1
#********EOF S50StartupScript File*************************
chmod 777 S50StartupScript
The configuration stage when using IEEE 802.11 WLAN has been completed. When compared to the two studies,  is more wasteful on both memory consumption and electricity consumption than . In the study  the memory consumed was 16.9MB from 29.8MB, while at  only consumed 13.6MB from 29.8MB. Electric power consumption can be seen in Figure 7.
From this paper, the following conclusions can be drawn:
- The Linux kernel is cross-compiled to the Imote2 platform first. The next process builds the filesystem and prepares the bootloader.
- To embed the bootloader, Linux kernel, and filesystem on the target via the JTAG interface using OpenOCD software, the process is called flashing.
- Target configuration includes automatic activation of IP addresses, SSHDs, and radios via serial connection, by linking to configuration scripts in RC level 2 and level 5.
- From research  and  use transmission media with the IEEE 802.11 WLAN standard on the Imote2 platform it is more wasteful of memory and power than using transmission media with the IEEE 802.15.4 ZigBee standard.
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