IEEE 802.15.4 subsystem
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| 1 | IEEE 802.15.4 Low-Rate Wireless Personal Area Network (WPAN) |
| 2 | ============================================================ |
| 3 | |
| 4 | |
| 5 | IEEE 802.15.4 defines physical layers and a media access control for |
| 6 | wireless networks. ZigBee and 6loWPAN are based on IEEE 802.15.4. |
| 7 | |
| 8 | This project aims to add experimental WPAN functionality to the Ben |
| 9 | NanoNote, in order to permit evaluation of overall network performance |
| 10 | and to examine possible integration into future devices. |
| 11 | |
| 12 | This work is licensed under the terms detailed in the file COPYING. |
| 13 | |
| 14 | |
| 15 | Hardware history |
| 16 | ---------------- |
| 17 | |
| 18 | IEEE 802.15.4 transceiver chips are available from several manufacturers, |
| 19 | including Atmel, Freescale, and Texas Instruments. These chips are similar |
| 20 | in size, functionality, and cost. The first prototype of this project was |
| 21 | based on the Atmel AT86RF230. |
| 22 | |
| 23 | The initial plan was to place the RF module on the left side of the LCD |
| 24 | module of the Ben NanoNote, replacing part of the display's PCB. When |
| 25 | installed in the Ben, the transceiver would connect directly via SPI to |
| 26 | the Jz4720. For development, a SiLabs C8051F326 microcontroller |
| 27 | implemented a USB to SPI conversion. |
| 28 | |
| 29 | Then Rikard Lindstrom came up with the idea of using the Ben's 8:10 card |
| 30 | slot as a general expansion interface, which led to the idea of making |
| 31 | a WPAN card in that form factor, with the benefit of being readily usable |
| 32 | with any Ben already in existence. |
| 33 | |
| 34 | Thus the project was split in two parts: the atben card that had only the |
| 35 | transceiver chip and would be used with the Ben, and the atusb card that |
| 36 | would be similar to the original design but abandoned its clear physical |
| 37 | separation of USB and RF. |
| 38 | |
| 39 | Meanwhile, an improved version of the AT86RF230, the AT86RF231, became |
| 40 | available and the designs were updated for it. It also turned out that |
| 41 | the clock from the Ben was too noisy to be used as a clock source for |
| 42 | the transceiver. Therefore, a crystal was added to the atben design. |
| 43 | |
| 44 | Finally, the SiLabs C8051F326 was replaced by an ATmega32U2, mainly |
| 45 | because the latter has a larger Flash memory and greater community |
| 46 | acceptance. |
| 47 |
