FINDING NEMO10 FINDING NEMO10
Take the pain out of putting your robot’s remote
sensor to work by translating its RS-232 data stream
into a TCP/IP packet.
by Fred Eady
Gathering sensor data with a
robotic device usually entails some
sort of 802.15.4 network. If you
want to forward the collected data
to a remote site, then TCP/IP is
required. The hardware and
firmware to move those special
little bits of sensor data can be very
complicated to build and program.
However, I've devised a way to take
the pain out of putting a remote
sensor to work. My method does
not require one byte of user written
TCP/IP code and you don't have to
scratch-build any Ethernet devices.
50 SERVO 10.2012
www.servomagazine.com/index.php?/
magazine/article/october2012_Eady
Discuss this article in the SERVO Magazine
forums at ttp:// forum.servomagazine.com
The Big Picture
Let’s start at the sensor end. It
really doesn’t matter what you are
sensing or what you are using for a
sensor as long as it can provide
analog or digital data that can be
represented in binary. The sensor
passes the binary data along to a
resident microcontroller via the
microcontroller’s analog or digital
inputs. Once the microcontroller
massages the data and assembles it
into a data package, the formatted
data is passed to a short-range low
power 802.15.4-based radio.
Radios need each other. So,
there’s probably another 802.15.4
radio within ear shot of the sensor
radio. The data stops here unless you
have equipment installed that will take
those sensor bits on a ride to
somewhere else.
I’ll leave the nature of the sensor
to you. However, I’m going to put a
PIC18F4620 between your sensor and
a Microchip MRF24J40MA 802.15.4
data radio. On the remote end, I’ll
place another PIC18F4620 behind yet
