standard XBee dual 10-pin footprint which will allow us to
communicate using 802.15.4 or Wi-Fi.
Depending on the application needs, we can deploy a
standard XBee radio, an ACKme Wi-Fi radio, or a Roving
Networks WiFly radio. I’ve seen other XBee footprint-compatible radios that should work in this environment, as
well. The idea is to be able to plug and play these variants
per our application requirements.
Let’s take the road less traveled. Instead of designing
in a standard LDO linear voltage regulator, we’ll design
and install a switching regulator. The advantages of our
switching regulator design include a small footprint,
minimal heatsink area, and a wide input voltage range.
Our switcher will be based on the Microchip
MCP16301T which can provide + 3. 3 VDC at up to 600
mA. The input voltage supplied to the MCP16301T can
range from 4 to 30 VDC.
The MCP16301T’s wide input voltage operational
range allows our multipurpose communications node
design to be easily powered by a cheap 9 VDC
unregulated wall wart. This is flight tested hardware. I’ve
used this power supply design for a number of other
projects. I’ve included an aerial view of this power supply
circuit for your enjoyment in Photo 1.
70 July 2015
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■ Schematic 1. This is where
the rubber meets the road.
Most of the peripherals we
will be communicating with
utilize a serial interface. So,
we've taken advantage of
■ Photo 1. The PCB layout doesn't give you a good visual
perception of the switching power supply. This overhead
shot should bring things into perspective.