http://forums.leaflabs.com/topic.php?id=2401 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:20:02 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=2401#post-12449 Wed, 15 Aug 2012 13:41:46 +0000 Anonymous 12449@http://forums.leaflabs.com/ <p>I have noticed that if I draw too much power from the Vin Pin while hooked up to external power, the board will reset, or at least the charge LED goes from Green to Red. </p> <p>Normally on an Arduino, the Vin pin is a straight shot to whatever is coming into the board. I checked the schematics for the Maple, and there is a diode in-line with the power before you get to the power jumper block. Bypassing this diode seems to alleviate the problem, so I am guessing that 400mA@5V is just too much for that diode. :/ Instead of de-soldering the diode or bridging it with solder, I simply built a 5V power supply and attached it across Vin and GND so that I can power the rest of my stuff directly from the power supply and not from the Maple.</p> <p>If you power from USB, you do not involve this diode, so using an external 7.5VDC PS may cause you the same grief. You can hook up directly to Vin/GND and set the jumper to EXT so that you don't run into problems when attaching a USB cable to your PC. That is how I do it. </p> http://forums.leaflabs.com/topic.php?id=2401#post-12342 Sun, 12 Aug 2012 22:20:57 +0000 pico 12342@http://forums.leaflabs.com/ <p>Ooops... found the problem, a bit embarrassing. I'm not going to admit to _too_ much, but should say that I don't think the reset pin (which is the one _next_ to the 3v3 rail pin) makes for the most reliable power supply for your peripherals!</p> <p>Thanks for your help, guys.</p> <p>BTW, what do you think about my assumptions that powering via USB should give me more headroom than via the 7.5VDC external PS. Is it comparing apples and apples or not? </p> http://forums.leaflabs.com/topic.php?id=2401#post-12339 Sun, 12 Aug 2012 20:01:29 +0000 crenn 12339@http://forums.leaflabs.com/ <p>What type of transistor are you using to drive the SS relay? BJT?</p> <p>I'd suggest isolating the radio itself and seeing if you can reproduce the issue. Can you provide us with a circuit diagram (scanned drawing works!) of how things are hooked up? </p> http://forums.leaflabs.com/topic.php?id=2401#post-12338 Sun, 12 Aug 2012 16:44:39 +0000 gbulmer 12338@http://forums.leaflabs.com/ <p>pico - what happens when you test each one of those current consumers connected individually?</p> <p>Pulling too much current might cause a reset.</p> <p>Try adding e.g. an LED to show a full reset (delay in setup before turning the LED on, so you can see if there is a full reset)<br /> There is a pin connected to the USB pull-up resistor, so accidentally changing it's state would look like a USB reset.</p> <p>Have you got a multimeter (or something) to measure the current draw?<br /> Disconnect from USB, and measure the current into the 7.5v DC pin.</p> <p>Possible thoughts:<br /> 1. The radio transmitter is being picked up on a track, and triggering reset<br /> 2. The SS relay is connected incorrectly and is shorting something </p> http://forums.leaflabs.com/topic.php?id=2401#post-12336 Sun, 12 Aug 2012 11:08:26 +0000 pico 12336@http://forums.leaflabs.com/ <p>I'm trying to get a radio transmitter working on a Maple 5. It draws a max of about 12mA or so when active, &lt; 1mA otherwise.</p> <p>The problem I'm having is that when I switch the radio from standby to active in software, the USB connection resets (in fact, the Maple 5 may be doing a complete reset itself -- not entirely sure.)</p> <p>Is this expected behaviour if you attempt to draw too much power from the 3.3V rail? I'm running it at 7.5DC Vin, so PD/(Vin - Vout) should be 0.37/(7.5 - 3.3) = 88mA total available. Board itself is supposed to take up about 30mA, leaving about 58mA to play with, I was thinking. I'm also reading a 10K thermistor and driving a transistor to actuate a SS relay. </p> <p>The radio generates a low interrupt which I've got set up on D2.</p> <p>I'm initialising with:</p> <p>pinMode(IRQ_PIN, INPUT_PULLUP);<br /> attachInterrupt(IRQ_PIN, radio_irq_vect, FALLING);</p> <p>Any other ideas of what might be causing my symptoms? Does drawing too many mA sound plausible to explain these symptoms?</p> <p>One other thing: It does this if powered by the USB connection, with or without the 7.5DC power supply being connected as well. (The reason I mention this is the USB would only supply 5V as Vin, so that should give me even more headroom to play with, I would have thought.) </p>