I SPI with my little eye...

If you're trying to work with SD cards on a microcontroller setup you designed yourself, there's a good chance you have to write the low-level SPI drivers.

This page: http://bikealive.nl/sd-v2-initialization.html

Was indispensable for me recently when trying to figure out why I could not read an SD card. It turned out that an on-board regulator for one of my parts was expecting 5 Volts, so when supplied with 3.3 Volts,  it was supplying ~2.3 Volts to the SD card, and it was not operating reliably. Once I told the SD card to operate on 2.7-3.3V, it would stop responding.

I placed a serial print statement in my low-level "spi-send-byte" function that printed the byte transmitted and the byte received, and it let me follow along the initialization sequence outlined in the above link and see where things went screwy.

--P

Tiny Gecko + Microchip Wifi Project.

The good folks over at Farnel (Newark in North America) got me hooked up with a 802.11b "Wifi" board that uses a 3 wire, "SPI" interface to do Wifi.

You can find it here:

I've decided to combine it with my Tiny Gecko board, I'm not sure what I'll do with it yet, it may not even be a permanent marriage of devices. (Both of these devices fall into the category of "I acquired these cool shiny toys without an actual purpose in mind, but just that they looked cool"). My purpose is to just see how easy it is to get up and running with an embedded wifi setup, and get inspired for some other uses along the way.

In this first of several posts about this effort I will focus on my first impressions with the MRF24WB0MA wifi board.