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Junior Member
 
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Last Login: Friday, May 02, 2008 2:02 AM
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| hi i will like to know what is the voltaeg that the gpi/o is transmitting. can anyone guide? because i am am trying to allow my robot to fire a row of LED, and my transistor minimum is 0.8v, is the board giving out that much voltage?
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Junior Member
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| aww sorry guys, i found the answer in the other treads. look under the 1st topic for the forum, u will get the answer.
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Supreme Being
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Last Login: Monday, October 31, 2011 9:18 PM
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Looks like previous posts on the forum are starting to be very helpful!  That's the point.Glad you got your question answered!
Jason Summerour
President,
Summerour Robotics Corporation
www.roboticsconnection.com
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Forum Newbie
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Last Login: Saturday, February 28, 2009 7:07 PM
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I'm trying to use the GPIO port 0 and 3 to control strings of 12V LEDs. Previously, I've had success using 4 LEDs in series (~4V) goes on when I set the state high. Been working fine for past 2 years. I'm building a new larger model and i'm planning to use the 4.4V high state to control a relay or Transistor Switch to power up a 12V string of LEDs. Can anybody recommend a circut. The one I designed runs hot. I was considering incorporating an AND Gate to switch a relay on and off?
Fred Kendall
Robot Satellite Builder
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Supreme Being
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LED's typically draw about 20ma each, while you did not say how many you have in a
string, you might use a Mosfet. It is good practice to not design using more than
a 75% rating of a component. ei; a 1amp rated transistor should not switch more
that 750ma. Radio Shack carry's a hefty TO-220 case mosfet that will switch
with a 5vDC input.
Personally I prefer to isolate high current circuits from my sensitive components
using opto-isolators. Your relay idea with a transistor and a couple of resistors would
do just fine too.
Don Lewis
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Forum Newbie
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Your suggestion worked great. I found this test circuit example and I have incoorporated into our design. I tested that it is only pulling around 47mA from the signal pin. I'm going to be repeating this circuit 7 times on this model and plan to utilize the IOWizard to control other LED strings on the model.
Thanks!
Fred Kendall
Robot Satellite Builder
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Supreme Being
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| Thanks for the tips guys! Fred, I'll get your BT modules updated tonight! I was busy getting our Robotic Applications section updated this weekend! Also, I got word from James Y. Wilson a few weeks back that he's REALLY CLOSE to finishing his port of the Serializer C++ Lib to Linux...So hopefully he'll be posting the latest source any day now. Best Regards!
Jason Summerour
President,
Summerour Robotics Corporation
www.roboticsconnection.com
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Junior Member
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| Hi Guys, run into this topic when I research for relay ideas. I want to use serializer to switch a motor/fan on and off, the motor runs 6 AA batteries, so it's not high voltage. I found some cheap used relay in a local electronic surplus store, that takes 5VDC to control the coil. My question is, can I use GPIO pins to drive the relay DIRECTLY? or I actually have to come up with a circuit to do it? Cause I was planning to connect the relay directly to GPIO Vcc and Gnd lines. I'm not hardware savvy at all so please advise.
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Supreme Being
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Last Login: Monday, October 31, 2011 9:18 PM
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| 250mA, and 5V. Radio Shack sells some 1A 5VDC relays that you can use if you're driving a load 1A or less. But, if you need to drive something more powerful, you will need to connect an I/O line to an external transistor that can drive a higher voltage/current load. I would measure the current draw of the motor to ensure you know how much it pulls. If the 5V relay can handle it (and the relay coil doesn't pull more than 250mA), then yes, you can use the relay to turn the motor on/off via a GPIO line.  Best Regards!
Jason Summerour
President,
Summerour Robotics Corporation
www.roboticsconnection.com
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Junior Member
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Last Login: Friday, February 12, 2010 12:20 PM
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| Jason, Thanks for the reply. When I use "setio" to set a GPIO pin to 1, exactly which pin I'm setting to 5V? Is it the Vcc pin or Signal pin?
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