Date:2013-02-04 23:33:17 (6 years 8 months ago)
Author:Werner Almesberger
Commit:1d069a101913623690e0ec67ecc5221baad5ff2d
Message:README: replace obsolete hardware description with the hardware history

Files: README (1 diff)

Change Details

README
1212This work is licensed under the terms detailed in the file COPYING.
1313
1414
15Hardware architecture
15Hardware history
16----------------
1617
1718IEEE 802.15.4 transceiver chips are available from several manufacturers,
1819including Atmel, Freescale, and Texas Instruments. These chips are similar
19in size, functionality, and cost. The first prototype is based on the
20Atmel AT86RF230.
21
22The RF module will be physically placed on the left side of the LCD
23module, replacing part of the display's PCB.
24
25When installed in the Ben, the transceiver will connect directly via SPI
26to the Jz4720. For development, a SiLabs C8051F326 microcontroller
27implements a USB to SPI conversion.
20in size, functionality, and cost. The first prototype of this project was
21based on the Atmel AT86RF230.
22
23The initial plan was to place the RF module on the left side of the LCD
24module of the Ben NanoNote, replacing part of the display's PCB. When
25installed in the Ben, the transceiver would connect directly via SPI to
26the Jz4720. For development, a SiLabs C8051F326 microcontroller
27implemented a USB to SPI conversion.
28
29Then Rikard Lindstrom came up with the idea of using the Ben's 8:10 card
30slot as a general expansion interface, which led to the idea of making
31a WPAN card in that form factor, with the benefit of being readily usable
32with any Ben already in existence.
33
34Thus the project was split in two parts: the atben card that had only the
35transceiver chip and would be used with the Ben, and the atusb card that
36would be similar to the original design but abandoned its clear physical
37separation of USB and RF.
38
39Meanwhile, an improved version of the AT86RF230, the AT86RF231, became
40available and the designs were updated for it. It also turned out that
41the clock from the Ben was too noisy to be used as a clock source for
42the transceiver. Therefore, a crystal was added to the atben design.
43
44Finally, the SiLabs C8051F326 was replaced by an ATmega32U2, mainly
45because the latter has a larger Flash memory and greater community
46acceptance.

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