the code. We checked the board, saw that pin 9
was denoted as RX and pin 8 for TX, and entered
It struck us as way too easy. The program,
however, compiled without incident. We uploaded
the program and opened the serial monitor. The
serial monitor declared that the board was unable
to connect to the Wi-Fi.
That struck us as strange. We had no problem
connecting to Wi-Fi with the previous demo
program. Fortunately, the Blynk forum is a
comprehensive resource for all things
troubleshooting, and we were eventually able to
discover the problem (though it had us feeling a
little silly). The Wi-Fi shield was having trouble
connecting to the Internet because we had pushed
the shield farther down onto the Uno, and the
interference with the Wi-Fi antenna was as
effective at messing up our Internet connection as
was someone using the phone when you were
using a dial-up connection.
We gave the shield a little more breathing room, and
the serial monitor no longer mentioned being unable to
connect to the network, but gave a different problem
instead. The serial monitor would give the cryptic message
“Failed to disable echo.” After returning to the supremely
helpful Blynk forums, we found the solution to this problem
too. We had incorrectly designated the RX and TX pins in
the program. Even though we went with the numbers as
they were printed on the board, in the program those
numbers actually have to be reversed. That’s not to say the
RX and TX pins as labeled on the Wi-Fi shield are wrong —
the issue boils down to a difference in definition — RX and
TX with respect to which device? In any event, swapping
the pin numbers put us in business.
We uploaded the fixed program and watched the serial
monitor with anticipation like what Marty and Doc Brown
must have felt as they exited the DeLorean to see whether
they really were taken back to 1955. The line “Connecting
to the network” hung on the screen for a few agonizing
seconds before the monitor confirmed that we were, in
fact, connected to the Internet. We started the Blynk app,
tapped the onscreen button, and when the claw jerked to
life we felt a feeling of triumph like what George McFly
must have felt when he knocked out Biff Tannen.
Each tap of the button would only open the claw a
little bit, so we went back to The Grid and made a new
interface using a slider. The slider opened and closed the
claw like a dream, and it showed impressive sensitivity.
And with that, we had inducted a robotic claw into the
Internet of Things.
Rover Phone Home
A claw is cool, but we wondered how effective the
Blynk app (normally intended for traditional Io T functions
like activating a light or something like that) would be for
controlling a robot. We rigged up a simple driving base
using two servos to power the wheels, but the Uno (or Wi-Fi shield) couldn’t accommodate both because there was
only one 5V pin. So, we busted out the SparkFun PWM
shield which comes with a whopping 16 PWM channels.
We soldered on some stackable headers and some female
headers for a few PWM channels. We wired up the servos,
stacked the shields, and soon had a super simple rover
eager to join the Io T. We set up a control panel with Blynk
using two sliders, and turned it all on.
It was not exactly to the point where we feared we
would have to dispatch a blade runner to track down and
retire it. The servos jerked a little bit, but were not really
responsive to the controls. We think the problem is that the
setup was a little too power hungry. We were running it off
of the wall power as recommended to increase the stability
of the wireless connection, but power requirements are a
big consideration when stacking more than one Arduino
shield. The Wi-Fi shield is one of the more power hungry
shields to begin with. The PWM shield — sourcing 5V pins
out the wazoo — is also a member of the power hungry
However, that doesn’t take away from the
awesomeness of the ease with which we connected the
Actobotics gripper to the Internet. The SparkFun Wi-Fi shield
and Blynk provide very promising (and affordable!)
platforms for initiating robots into the Io T.
No matter what Terminator says, we’re excited to keep
building and connecting bigger and better bots to the
SERVO 08.2016 59
INTERNET OF ROBOTS.