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[DPRG] iCreate Comments
Subject: [DPRG] iCreate Comments
From: Rud Merriam
k5rud at arrl.net
Date: Mon Jun 9 13:26:33 CDT 2008
Since you asked here are my impressions with the caveat that I am not
greatly experienced in robotics.
The pricing, IMO, is terrific for what you get. For under $200 you get the
iCreate and the command module. You can check out the specs on the iRobot
site for yourself. The Create is based on the Roomba vacuum so it is tough.
It is also strong with some projects carrying substantial weight for the
size of the device. Take a look at the Create forum which has technical
information and some completed projects.
The Create provides a platform with differential drive, some LEDs, and a
couple of switches. From the drive you can get distance and angle traveled.
Safety sensors include left & right bump switches, 5 cliff detectors along
the front, and wheel drop switches on the caster and drive wheels. These can
be left enabled in a "safe" mode or disabled in a "full" mode. There is a
TTL serial port but it comes with an RS-232 cable that handles the level
shifting. With just the serial cable you can write scripts that drive all
the actuators, report sensor information, and play songs. There is a 25 pin
connector in the rear "cargo area" that provides some digital and analog
I/O, including some PWM "low side" outputs that will handle additional
motors. The cargo area has 4 points for bolting in parts. Another 4 screw
points are on the top for bigger payloads. Additional internal sensors
report battery condition (voltage, current temperature, charge level) and
charging status, i.e. docked. Almost forgot there is an IR sensor that reads
modulated IR characters from the docking station, a remote control, and
virtual walls. Making an IR transmitter using a small micro and an IR LED
would be a neat project for beginners. They could see the robot, programmed
by the instructor, search for or bounce of their IR beacons.
The Command Module (CM) with the AVR168 adds a great deal. It plugs into the
cargo bay connector using the serial port for communications. (Once it is
installed the Create serial port is only usable for monitoring the data sent
by the create, i.e. receive is disabled.) The CM adds a switch and a couple
LEDs. There are also four ePorts that bring out a most of the AVR168 I/O.
That includes digital and analog I/O, TWI (I2C), SPI. The ePorts also expose
the heavy duty "low side" outputs from the Create.
I have been using the WinAVR development package that comes with the CM. I
did use AVRStudio to debug some code. WinAVR works fine, even doing C++,
which I prefer over just C. There are three example programs that really
show how to do the basics of working with the CM and Create.
My only complaint is that the CM's serial connection is a USB port. That is
used for programming the '168 and can be used for serial communication with
a PC. Being a USB there is no way to use it for a wireless channel back to
the PC which is something I would like to do. There is "bit bang" UART code
for the '168 using digital I/O and I may have to use it to go wireless.
Since I am going to use I2C for IR proximity and a compass I am considering
an I2C to serial to wireless setup. (Except then the '168 has to also act as
an I2C slave which is more complexity. <sigh>)
There is an alternative to the CM called a Bluetooth Adapter Module from a
3rd party. It exposes some I/O from the cargo bay connector and may have
some of its own. But it is not programmable itself. It just provides a
wireless connection to a PC.
Hope this helps. Holler if you have more questions.
Rud Merriam K5RUD
ARES AEC Montgomery County, TX
http://TheHamNetwork.net
Hi Rud,
I second the request for more info on your impressions on the iCreate. I've
used a Roomba as a platform before, and I think it'd be a neat way for
students to get into robotics quickly.
BTW, I'm a ham myself! But without any radios. So it goes.
Ed
KE5AYE
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