Figure 16. Battery powered configuration.
For this configuration, remove
the RF carrier board with the
Wi-Fi module from the
Experimenter, apply battery
power to the module, and
interact with the module directly.
We will use the TCP to remotely
control an LED from the host.
For batteries, we need to
supply + 4.5V to 6V to the
module; three to four AAA
batteries should do the job nicely.
We will use the J3 I/O port of the
RF module for external
electronics. For this experiment,
we will connect a 1K resistor to
the anode of an LED to pin GPIO
13 pin 7. This GPIO pin defaults
to an output. Connect the
cathode of the LED to ground
(J3 pin 10).
Open Tera Term (configured
for Telnet) using the IP address of
the module, and the port address
2000. You can double-check you have the right address
by utilizing ping. Tera Term should respond with an
*OPEN,* indicating a TCP connection. Type “$$$” to
enter command mode.
We can control the state of the LED through the
RN-XV I/O commands (detailed in the API). In the set,
“sys output <value> < mask>“ (CR), value is what is
written and mask designates the pins. Type “sys output
0x2000 0x2000” (CR) to turn the GPIO 13 LED on
and “sys output 0x0000 0x2000” (CR) to turn the GPIO
13 LED off.
Figure 17. Battery powered configuration controlling LED.
We covered some important ground in Wi-Fi, but
have barely touched on all of the extensive capabilities of
the Roving Networks Wi-Fi module. Wi-Fi can be tricky.
However, the software tools, code examples, and
hardware used here should be invaluable in your future
Future articles will cover FTP, HTML clients, and UDP
applications. The Experimenter is readily poised to handle
your wireless applications. Until next time, happy 32-bit
Wi-Fi computing! NV
March 2013 47