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June 27, 2012
Robotics teacher at International School Manila
I recently used these in class to make mobile robots. We used VEX hardware with VEX motors. Powered by arduino unos and ardumoto shields. The robots were extremely sensitive to fluctuating battery levels. If your VEX 8V batteries were just below 8 V, the robot would cease to perform parts of the code. It would also stop reversing direction or making turns. Upon using a 9V wall wart, the same glitches would appear. however, a properly charge battery would work.
Now doing this project with students and having a new problem. Particular channels from the shield will stay on, even though our code says to turn them off. Upon jiggling the offending wire, it will shut off, but then then when the code turns it on again, it must be jiggled again, otherwise it remains on forever. If i move offending wire to a new channel, the problem follows the wire.
This seems to appear for students who are using the 12V inverter (with SJ1 closed). Those students with the 3 V inverter do not seem to be having this problem. any thoughts on why this is?
I can’t find see any problem with the offending wire, nor understand why the problem appears only with the 12V inverter?
about 2 years ago
i think i solved this by going to http://www.ftdichip.com/Drivers/VCP.htm. i downloaded driver 2.2.18 which seemed to work for max OS X. Now when i select my board as Arduino Uno, serial ports show up, and code transmits. hopefully this problem / solution can be added to the quick start tutorial.
My Mac recognizes an Arduino Uno with no problem, but does not seem to recognize the RedBot board. (no tty usb serial option shows up when it’s plugged in). I don’t need to install a new driver for this do I? I am using arduino 1.0.5 with OS X 10.8.5. Any ideas on how i can get the board recognized?
about 2 years ago
i think i solved the problem. I got an adjustable voltage wall wart and turned it down to somewhere between 7 and 8 volts. (my previous power source was 9 V). Now it’s been running for over an hour with no glitches. Thanks for the trouble shooting!
I have tried this on USB power, and have not noticed it locking up. however, i have only tried the USB power for maybe a few minutes at a time. (the locking up usually occurs after a leave for awhile). the wall wart is 9V and i use a 3V inverter.
i swapped the Manila-made arduino for the Italian-made Arduino-Uno. That fixed the freezing issue. However, on future EL-wiring projects for my students, i’d like to still use the locally made arduinos. Any thoughts on how i can keep them from freezing? In order to power the inverter seperately from the Arduino, what is the easiest way? i don’t have to use 2 wall warts do I?
i ran the same code with the status light blinking. When it freezes, one wire stays frozen on (usually the same wire), and the status light also freezes. so i guess the manila-produced arduino is freezing up.
I am powering the arduino / sheild with a 9 V wall wart. i then use an El Inverter 3V between the arduino and sheild. Should i use the El Inverter 12 V? i have that product also, but have not connected it yet because my project is so small. all 8 of my EL wires are only about 20 cm. I also have an imported name brand Arduino. Should i use that and see if the freezing up still occurs?
I made a small project with 8 small sections of EL wire connected to El Escudo, and then placed on a locally made arduino (Gizduino, made here in Manila). When i sequence the lights with a loop, it always glitches and gets frozen on a particular wire. It seems to be hardware related, because when i change the code, it glitches on the same wire. Recently, i took the shield off the arduino to inspect for problems. When i replaced it, the glitch had moved to a new wire. Any thoughts as to why?
This will be for ISM’s new Robotics for Makers Course
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