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47 lines
2.0 KiB
Plaintext
47 lines
2.0 KiB
Plaintext
IEEE 802.15.4 Low-Rate Wireless Personal Area Network (WPAN)
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============================================================
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IEEE 802.15.4 defines physical layers and a media access control for
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wireless networks. ZigBee and 6loWPAN are based on IEEE 802.15.4.
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This project aims to add experimental WPAN functionality to the Ben
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NanoNote, in order to permit evaluation of overall network performance
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and to examine possible integration into future devices.
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This work is licensed under the terms detailed in the file COPYING.
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Hardware history
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----------------
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IEEE 802.15.4 transceiver chips are available from several manufacturers,
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including Atmel, Freescale, and Texas Instruments. These chips are similar
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in size, functionality, and cost. The first prototype of this project was
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based on the Atmel AT86RF230.
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The initial plan was to place the RF module on the left side of the LCD
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module of the Ben NanoNote, replacing part of the display's PCB. When
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installed in the Ben, the transceiver would connect directly via SPI to
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the Jz4720. For development, a SiLabs C8051F326 microcontroller
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implemented a USB to SPI conversion.
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Then Rikard Lindstrom came up with the idea of using the Ben's 8:10 card
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slot as a general expansion interface, which led to the idea of making
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a WPAN card in that form factor, with the benefit of being readily usable
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with any Ben already in existence.
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Thus the project was split in two parts: the atben card that had only the
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transceiver chip and would be used with the Ben, and the atusb card that
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would be similar to the original design but abandoned its clear physical
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separation of USB and RF.
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Meanwhile, an improved version of the AT86RF230, the AT86RF231, became
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available and the designs were updated for it. It also turned out that
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the clock from the Ben was too noisy to be used as a clock source for
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the transceiver. Therefore, a crystal was added to the atben design.
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Finally, the SiLabs C8051F326 was replaced by an ATmega32U2, mainly
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because the latter has a larger Flash memory and greater community
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acceptance.
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