December 15, 2004

Embedded Linux + SDIO WiFi update

sdlink11b.jpg
The C-Guys have been testing an 802.11b SDIO WiFi card with a Linux based driver, the SD-Link11b. The driver was designed for the Sharp Zaurus Linux PDAs. Note that the site is in Japanese. I found a thread on the SD-Link11b. It looks like it is still not market-ready and the drivers are not (yet?) open-source. Having to pay for software may well be what kills this idea.

PalmInfocenter has a snippet on the C-Guys.

Posted by torque at 11:12 AM | Comments (2) | TrackBack

Tiny WiFi card

I've been waiting for this one for a while - Sandisk + WiFi. An 802.11b WiFi card, packed into an Secure Digital (SD) card with 256 MB to boot. How much, a measely $106.49. Nice. Socket Com also have a similar item - the SDIO WLAN CARDSDIO 802.11B. Amazon list's it for a whopping $1,893.99, though I think this might be for 20.

What I want to know is what software needs to be run on the primary processor in order to get this to work. Is everything mostly on the card already? Or is it relying on the local microprocessor to do the work. If the former, this could be a cheaper way of enabling devices to have WiFi - at least for a hobbyist. We could use embedded Linux. Are there Linux drivers for SDIO 802.11b? Discussion here. The answer, at the moment, appears to be no. A link was made to a Fujitsu document, but this seems to have been removed.

The SDCA is a huge believer in "security through obscurity". Sharp went as far as to offer closed-source drivers for SD memory cards, but I doubt we'll be seeing any SDIO drivers for Linux until the Bulgarian high school students break the security and spread the secrets all over the net.
Go Bulgaria!

Posted by torque at 10:57 AM | Comments (0) | TrackBack

January 8, 2004

A conversation with Analog Devices

I spoke with Tim at Analog Devices regarding my requirements, essentially, at 0.01 - 100Hz, noise below 100 nV/&sqrt;Hz, and fA input bias current. We first looked at the AD549, which has 60 fA input bias current, but really high 1/f noise. Then we looked tat the AD8551, a CMOS chopper architecture with pA input bias current. He said that he could not do both chopper and fA input bias current. Finally, we looked at the AD8605, which seemed to be a good compromise between the two. I'll have to look in more detail. Recall the LMC622 has 2 fA input bias current, but rather high noise... what I really need is a chart comparing everything.

Posted by torque at 2:06 PM | Comments (0) | TrackBack

April 15, 2003

Wireless data

I need to transfer 8 channels x 32x200 bps = 51200 bps continuously. A buffer may be necessary - hopefully not. Based on some earlier work, it seems that life would be simplest if we used something like the TR1000 from RF Monolithics. The sales person suggested the DR2000, which packetizes the data and does some error correction. A microcontroller will be used to take data from 8 ADCs, multiplex them, and transmit them. We may be able to use some Atmel facilities on campus.

Posted by torque at 3:57 PM | Comments (0)