WiFi is something we have wanted to do for a long time, but there are a lot of technical and regulatory challenges around it. If you’re running an OS on an embedded PC like the Raspberry PI, WiFi is simple, you buy a cheap dongle and the intelligence is in the driver.
For a low power embedded project where you’re not running an OS it gets a lot harder and that means it’s expensive. So the only real option is to use a WiFi module and these are normally expensive.
A few months ago, whilst designing the DipCortex, we identified a module that is low cost and comes with FCC, IC & ETSI certification, saving huge costs assocaited with getting radio equipment through testing. The goal was to squeeze this module, the TI CC3000MOD, on to a board the same size as the DipCortex which was a massive challenge, as the DipCortex is sized to replace a 40pin DIP package.
This week the PCBs arrived, we assembled, re-flowed and powered them up, flashed the Cortex M3 with our code and connected to WiFi, a complete success! The PCB outline had to be extended slightly past the standard DipCortex footprint, to enable us to get all of the components on the top side, reducing assembly costs. We also had to sacrifice the reset button, so boot loading via USB is now done by removing the USB lead and re-connecting it whilst holding the boot button. Switching to a Micro-USB connector gained us some valuable space as well.
We have spent a lot of time routing and re-routing the board to perfect the layout, it is 4 layer like the standard DipCortex with full power and ground planes. The modules datasheet has advice for the ideal PCB layout and the 50 ohm microstrip leading to the antenna which we have followed closely to ensure good wireless performance.
For more detail: WiFi DipCortex An embedded WiFi module to power your next product
