Thursday, April 30, 2015

Building a CC2500 to BLE Adaptor

Posting some details in response to questions about the current module.  Everything for the CC2500 is on Github,  Fish around here and you'll also find some iOS and Pebble code.  Sorry, nothing Android based.  

The RFDuino is programmed like any other Arduino, it's worthwhile to use their usb shield.  The CC2500 is controlled via SPI(from the RFDuino), there's nothing to program.


The schematic is missing the 3 volt regulator (Pololu), and the battery for that matter.  I just added pads for it into the PCB, I don't spend much time in Eagle, so it's a painful experience.  One jumper in this version, from the CC2500 VCC to +3, you'll see the pads in the middle.  Also, I've added a 100 micro farad electrolytic capacitor across the +/- leads.  The device tends to crash when you plug it into the charger, the Cap reduces this (maybe).  Not really a big deal, since all this does is relay what the CC2500 receives to the iPhone.  

Everything is surface mounted, whether it should be or not.  Keeps the board thin, and drilling is a pain.  The device is always on, makes for some fear when soldering the lipo, YMMV.

Still considering going thinner by using a smaller battery and recessing it into the board.  But, we're talking about a 0.1" improvement.  Battery life with a 110 mAh lipo is about 48 hours.