Versions, F. i/o repeater app, Overview – Pololu Wixel User Manual
Page 44: Installation instructions, Description, Section 9.f
Versions
•
(26k wxl), released
2011-05-03: Initial release.
9.f. I/O Repeater App
Overview
This app allows you to wirelessly extend the reach of your
microcontroller’s I/O lines up to 50 feet using two or more Wixels.
An input pin on one Wixel can be mapped to an output pin on
another Wixel. When the input pin reads high, the output pin will be
driven high (3.3 V) and when the input pin reads low, the output pin
will be driven low (0 V). Each Wixel can have up to 15 input pins,
15 output pins, or a mixture of input and output pins. Each input pin
can map to one or more output pins on one or more Wixels.
Installation Instructions
Download the
(22k wxl). Open it with the Wixel Configuration Utility, choose your settings,
and write it to two or more Wixels. See
for more information on how this is done.
Description
The following 15 pins on each Wixel can be used as inputs or outputs (or be disabled):
• All the pins on Port 0: P0_0, P0_1, P0_2, P0_3, P0_4, P0_5.
• All the pins on Port 1: P1_0, P1_1, P1_2, P1_3, P1_4, P1_5, P1_6, P1_7.
• Pin P2_1 (the red LED pin).
The behavior of each pin is determined by its link ID, which is a parameter that you can set individually for each
pin on each Wixel using the Wixel Configuration Utility. A link ID of 0 means the pin will be disabled (it will be an
input but its input value will not have any effect). A negative link ID between -1 and -127 means that the pin will
be a digital input and its value will be transmitted over the radio. A positive link ID between 1 and 127 means that
the pin will be a digital output and its output value will be determined by the input value of the pin with the opposite
(negated) link ID on another Wixel. For example, if the P1_3 pin on one Wixel has a link ID of -13, then it will be
a digital input and its value will be reflected on all the output pins that have a link ID of 13 on all the other Wixels.
Input pins do not have any effect on output pins that are on the same Wixel.
If a Wixel is running this app and has one or more pins configured to be inputs, then it will transmit a single radio
packet every 7–10 ms that contains input values and link IDs of all of its inputs. Any other Wixel that successfully
receives this packet will process it and use it to update the state of its output pins.
This app will work with more than two Wixels on the same radio channel. In that case, make sure that you do not have
multiple input pins on different Wixels with the same link ID: otherwise, the corresponding output pin(s) will change
state unpredictably whenever there is a conflict between the different input pins. It is OK to have muliple output pins
with the same link ID.
Every pin configured as an input has an internal 20 kΩ pull-up resistor except P1_0 and P1_1, which float when they
are inputs. This means that if you leave the input pin disconnected, it will be pulled high by default.
Each output pin will drive low (0 V) by default before any radio packets are received that change its state.
Pololu Wixel User's Guide
© 2001–2014 Pololu Corporation
9. Wixel Apps
Page 44 of 64