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13756  Forum 2005-2010 (read only) / Troubleshooting / Re: digital in sensitivity - building a fencing box on: February 16, 2009, 01:12:11 pm
While your explaination is good I think that you need to supply a wiring diagram showing the switch, light, voltage source, ground and connection to the Arduino. I'm sure there is something simple that can be done either with external components or with software to make it function like you wish, but more circuit detail is needed.


13757  Forum 2005-2010 (read only) / Troubleshooting / Re: Can I use pin 9 (PWM) as digital input on: February 16, 2009, 01:04:00 pm
As stated you are fighting a floating input signal.  A simple software fix is to add a digital write in your setup section and this will apply a 'soft pull-up' to the input pin and it should then read as a high until wired to something externally (like a switch wired to ground) that can pull it low when desired.

 pinMode(testPin_i, INPUT);
 digitalWrite(testPin_i, HIGH);   // This will activate the internal pull-up.

13758  Forum 2005-2010 (read only) / Troubleshooting / Re: external supply/USB programming, ground problem? on: February 16, 2009, 06:52:19 pm
You didn't state which model you have, but generally there is no problem using the USB port no matter what source of power is active or not.


13759  Forum 2005-2010 (read only) / Troubleshooting / Re: sourcing and sinking... on: February 15, 2009, 08:01:00 pm
Glad to help, hardware I can help with sometimes It's the software side side that kick's my butt all to often  smiley-wink

Switching time becomes more important when one is trying to utilize PWM to large current loads. That is where it is easy to burn up the MOSFETS even though there spec sheet says they should be able to handle the current.

When the MOSFET is in transition between on and off that it's heat dissipation can go through the roof when trying to switch high currents. That is where nice low impedance drivers, driving the MOSFET gate, can really help out as it forces the transition time to be as short as possible.

13760  Forum 2005-2010 (read only) / Troubleshooting / Re: sourcing and sinking... on: February 15, 2009, 07:17:42 pm
The source impedance of the driver when high (2.5k) and your 2K pull down resistors are forming a voltage divider such that the gate can only raise to 2.2 volts, which is not enough to fully turn on the MOSFET.

So either eliminate the pull down resistors or change them to say 50K. There still will be a switching time limit as the MOSFET has a input capacitance of around 1,000pf that the driver has to charge or discharge and the limited driver impedance keeps the switching speed limited to the total RC time constant.

So first play with those pull down resistors and see if you can't get better results.
13761  Forum 2005-2010 (read only) / Troubleshooting / Re: N00B--DC motor on digital pin 13 not running? on: February 12, 2009, 09:12:51 pm
Yes, run the motor again by wiring directly to 5vdc but this time measure the current with your meter and tells us what it draws.


13762  Forum 2005-2010 (read only) / Troubleshooting / Re: disconnect - reconnect usb port behavior question on: February 11, 2009, 06:42:51 pm
Well a module like this could be easily mounted to a shield proto-typing board:

Flash memory module:

Proto shield:
13763  Forum 2005-2010 (read only) / Troubleshooting / Re: disconnect - reconnect usb port behavior question on: February 11, 2009, 05:36:21 pm
I suspect the autoreset feature from opening or closing communications is at the root of what you are seeing. One solution might be to save your data variables in the EEPROM ,if it's big enough or use some kind of shield mounted non-volitable memory that your program can utilize.

13764  Forum 2005-2010 (read only) / Troubleshooting / Re: Loss of USB power on Ardiuno Nano on: January 29, 2009, 03:26:52 pm
"Measuring the voltages across the D1 diode, the cathode was +2vdc, and the anode +5vdc. "

Well if those voltage readings are correct, and the board works fine if powered from external power then that Diode is bad.

A quick check would be, with no external power applied, temporaily wire a jumper across the diode and see if all works fine when plugged into a PC USB port.


13765  Forum 2005-2010 (read only) / Troubleshooting / Re: Loss of USB power on Ardiuno Nano on: January 28, 2009, 06:10:04 pm
You can make some voltage measurements to try and isolate the problem. Hook the nano up to the USB port on the PC without external power applied. Now measure both sides of the D1 diode. If the anode side measures +5vdc but the cathode side reads 0vdc then the diode is bad.

If there is zero volts on both sides then there is possibly a bad trace or connector connection to the USB connector, try measuring right at pin 1 of the mini-B connection. If not there then it's possible that you blew open an internal fuse for that USB port on you PC. Have you tried using a different PC USB port?


Here is a link to the drawings for a NANO
 D1 Diode, Schottky 0.5A 20V MBR0520LT1G ONSemi 863[ch8208]MBR0520LT1G Mouser
13766  Forum 2005-2010 (read only) / Troubleshooting / Re: Using the tx rx pins on Arduino Duemilanove on: February 07, 2009, 11:17:50 pm
Any chance I could have fried the vdip2 if I tried to use RS232 serial on it?  Geeze, I hope not.  
Back to top  

Normally applying a RS-232 level voltage (which can vary between +/- 3vdc to +/- 15v) can cause damage. However if the the voltage source is current limited then even though the negative or positive voltage were enough to cause the input protection clamping diodes to conduct, there may be no permanent damage due to the current limit set by the RS-232 output drivers. So if your vdip2 has internal clamping protection diodes like the Arduino does,you might have dodged a bullet on this one.  smiley-wink

13767  Forum 2005-2010 (read only) / Troubleshooting / Re: Digital pins PWM on arduino (Diecimila) on: February 07, 2009, 10:46:47 pm
Yes, they can be used as general purpose Input or Output pins as well as PWM pins.

13768  Forum 2005-2010 (read only) / Troubleshooting / Re: Arduino -> Arduino (New to Arduino) on: February 06, 2009, 10:33:03 pm
I am trying to send the data from Analogue Output (pin pwm 11) of that board to a Arduino Duemilanove (Arduino2), where the data is received on Analogue In (pin 5) and read by the PC to which it is connected. This is the receiver unit.

You cannot wire a PWM "analog" output pin directly to a analog input pin as a PWM signal is not a real analog voltage but rather a series of highs and low of variable duty cycle. One must first filter the PWM signal with a low pass filter to obtain a true analog voltage that can then be wired to a analog input pin.

13769  Forum 2005-2010 (read only) / Troubleshooting / Re: Low Voltage problem on Pin4 on: February 02, 2009, 01:26:47 pm
All I can suggest is doing the electrical tests I gave prior and getting back to us with the results.

13770  Forum 2005-2010 (read only) / Troubleshooting / Re: Low Voltage problem on Pin4 on: February 01, 2009, 12:10:08 am
Again most bizarre. I just now of course loaded your sketch into my serial clone arduino (with the same shield connector layout) and of course I get 0v for a sec and 4.98v for a sec.

Another poster here stated they also saw no problem when trying your code. So we know the code is good and at least two of us can't duplicate your symptom.

 So I guess your next step, if you have a steady hand is try and measure the output right at the 168 chip, which is pin 6 (TO) PD4 at it's socket location. You will need a sharp point on your meter lead. If it's good there then you may have have a high resistance solder joint or intermittent broken trace at the shield connector pin 4, or just making bad contact to the pin4 socket hole.

If it still measures bad right at the chip's pin then the next test is tricky but required. Power off the board and pull the 168 out of it's socket, then gently bend it's pin 6 straight out. Reinsert the chip, re-power the board and measure it's pin six again. If it's still bad then the 168 chip's pin busted, however if it then reads good then you have some kind of partial short circuit on the boards tracing or the pin 4 connector, causing excessive current to flow forcing the pin's output voltage to lower.

PS: The most bizarre part is you finding a friends board doing the same thing. However we can only troubleshoot one board at a time. Is it possible a shield is warped or misaligned somehow and is damaging the inside of the pin4 socket on the Arduinos? Just a WAG. I guess it's also possible that when you added the shield board some component or wiring error on the sheild caused too much current to be drawn from pin4, damaging it. Did your friends Arduino have your shield plugged into it at any prior time?

Good luck and left us know what you find.

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