Monday, November 21, 2011

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.

The first thing I realized when I opened the board was that I should have taken a better look at the datasheet. The pads are 1.27mm pitch, I'd planned to solder some headers to the pads, but I only had 2.54 headers. There's a boat somewhere between here and China with my itty bitty headers.( It's actually probably on a truck in Iowa somewhere)

 The second thing I realized after finally checking out the datasheet was that Microchip only really supports using the board with Microchip microcontrollers. The data sheet does not document the SPI interface. What they do provide is the source code for their wireless TCP stack on a PIC family. Being a software guy, I'm used to code as documentation. The code is freely obtained on Microchip's website, but it explicitly prohibits redistribution if modified for another brand of processors. So I can't publish any changes I make. I wish I had known that beforehand, I may have looked for another device, this restriction seems a little excessive.

I browsed around in Microchip's wifi code, and found where it issues SPI commands to the board. My plan is to replace the PIC specific SPI code with SPI code for the Gecko. I've still got IAR Workbench installed on my machine from when I went to the Energy Micro seminar.

To be continued...


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