http://forums.leaflabs.com/topic.php?id=884 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:12:51 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=884#post-5482 Fri, 01 Jul 2011 13:57:06 +0000 poslathian 5482@http://forums.leaflabs.com/ <p>I often just use a little mosfet - rated up to whatever current is needed - for LED's. But you can get arbitrarily sophisticated with feedback constant current drivers and such. Thanks for throwing the tutorial on the wiki! </p> http://forums.leaflabs.com/topic.php?id=884#post-5442 Tue, 28 Jun 2011 18:59:40 +0000 nully 5442@http://forums.leaflabs.com/ <p>Ok, So the best way to do this is with 3 transistors, I'll revise my schematic then.</p> <p>Ultimately I will be chaining RGB LEDs via several ws2801's but thats for another time. </p> http://forums.leaflabs.com/topic.php?id=884#post-5436 Tue, 28 Jun 2011 11:17:07 +0000 gbulmer 5436@http://forums.leaflabs.com/ <p>nully - It depends on what you are trying to do.</p> <p>25mA is the absolute maximum from a pin.</p> <p>If you look at the device data sheet at:<br /> <a href="http://www.st.com/internet/mcu/product/164487.jsp" rel="nofollow">http://www.st.com/internet/mcu/product/164487.jsp</a></p> <p>section 5.3.12 "I/O port characteristics" says:<br /> "Output driving current</p> <p>The GPIOs (general purpose input/outputs) can sink or source up to ±8 mA, and sink or source ±20 mA (with a relaxed VOL/VOH)."</p> <p>I limit myself to 8mA in case I want to add other outputs, or someone else might use the circuit as a basis for something. At 25mA/output, two RGB LEDs would exceed the entire device current. </p> http://forums.leaflabs.com/topic.php?id=884#post-5432 Tue, 28 Jun 2011 07:29:45 +0000 nully 5432@http://forums.leaflabs.com/ <p>Thanks.<br /> Ah yeah, we moved servers today :( not going to be up for another week or so.<br /> I'll have to find somewhere to mirror it.</p> <p>The formatting isn't right, but its <a href="http://wiki.leaflabs.com/index.php?title=Maple_RGB_Led_Tutorial">here</a> as well </p> http://forums.leaflabs.com/topic.php?id=884#post-5430 Tue, 28 Jun 2011 06:30:41 +0000 snigelen 5430@http://forums.leaflabs.com/ <p>The absolute maximum is 25 mA per pin or 150 mA total.</p> <p>Your link doesn't work for me. </p> http://forums.leaflabs.com/topic.php?id=884#post-5427 Tue, 28 Jun 2011 04:11:11 +0000 nully 5427@http://forums.leaflabs.com/ <p>Hey all,<br /> I wrote a short, very simple guide to using PWM and a RGB LED,<br /> <a href="http://nulldragon.org/Maple-RGB-Led-Tutorial.ashx">Maple RGB Led Tutorial</a></p> <p>I have a quick question, how much current can i source from each PWM pin? </p>