Printed Circuit Board Has Arrived
The printed circuit boards for the latest BDB-5000 Bluetooth Doorbell prototype version 0.0.3 have finally arrived. They took longer to get here than I wanted, but you can’t beat the price of batchpcb.com for low volume prototype grade orders.
This picture shows the board, which I designed to fit in to the enclosure I showed in a previous post. Thankfully, all the mounting holes line up and it fits perfectly in the enclosure.
So far, I have only soldered two components on to the board for testing. Those are the Bluetooth radio (the white/blue module labeled RN-42) and a 6 pin header. In this picture the 6 pins have a red FTDI Basic board mounted to them which just slides on and off of the header pins for testing. The red FTDI Basic board will not be there permanently so it doesn’t have to fit in to the enclosure.
Both the FTDI Basic board and the Bluetooth radio module are available at Sparkfun.com
In prototype versions 0.0.1 and 0.0.2, I used a different Bluetooth radio made by Parani (the Parani ESD100V2). It worked well but had two issues that prevented it from being a perfect fit for this project.
One issue was that it cost $49.50 for one unit (that price would be lower if you ordered in high quantity). My new radio cost about $15 for one unit (and even that price would be lower in higher quantity). My goal with a future Kickstarter.com project is to raise enough money to order parts in high enough quantities to make the BDB-5000 Bluetooth Doorbell available as cheaply as possible to as many people as possible. This $35 price difference will make a big difference in the final price of the units.
The other issue is that with any Bluetooth radio I use for this application it will be necessary to put the radio in “sleep mode” when it’s sitting idle in order to save battery life. That means when you press the doorbell button, it will take some amount of time for the radio to wake up and send a command to the computer or phone. The Parini radio (used in the older prototypes) can wake up from sleep in “a few seconds” according to its documentation. And you can see from the v0.0.2 prototype demonstration video that it really does take a few seconds to wake up, which is not really acceptable. According to the documentation for my new Bluetooth radio, the worst case scenario is a wake up time of 5 milliseconds, which should be unnoticeable. It will take some time for me to send this radio through some testing to find out how this feature effects performance and battery life.
I have tested the board above after soldering the 2 components on, and I’m able to connect through USB to the FTDI Basic board and send serial data to the Bluetooth radio. I’m also able to connect via Bluetooth to the radio and receive information sent over serial. So it looks like we are in good shape so far. I’m sure the printed circuit board I designed will have some flaws that will get fixed in the next revision, but so far so good.