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1  Forum 2005-2010 (read only) / Playground Wiki / Re: Can't create new page in Playground wiki. on: October 18, 2010, 11:39:29 pm
I already have a playground login I used to create Thermistor4 before all the upgrades.
2  Forum 2005-2010 (read only) / Playground Wiki / Can't create new page in Playground wiki. on: October 17, 2010, 10:18:41 pm
I got my "AutoCapacitanceMeter" project done and was going to post it in the Playground, but it won't let me create a new page. I was going to put it in Tutorials beside the original/basic code. I didn't get this error before with my Thermistor4 project. I was also able to edit my Thermistor4 page without incident tonight.

Error is:
Insufficient privileges to perform action.

Can this be fixed for me? Or if someone wants to filter my work, that's also fine. I'd just like to get it posted.

3  Forum 2005-2010 (read only) / Interfacing / Re: communication with arduino via seral from linux on: October 17, 2010, 02:21:45 am
After the mentioned stty lines, I've been using the following:
tail -f /dev/ttyUSB0

That way the AVR doesn't reset with every "cat" line.

To get serial data in, I just use
echo -n "something" > /dev/ttyUSB0

...or leave off the "-n" if a carriage return is needed.
4  Forum 2005-2010 (read only) / Development / Re: Universal Thermistor4 Library added to Playground on: September 04, 2010, 08:53:50 pm
I've done a bunch of little clean ups to the page.

With no comments, I went ahead and released it. It's now linked off the main page.

Have fun.
5  Forum 2005-2010 (read only) / Development / Universal Thermistor4 Library added to Playground on: September 01, 2010, 04:03:53 am
As my first Playground addition, I added an upgraded thermistor library that addresses the issues of many others I've seen around the Net. It should be universal for most NTC thermistors.

Please click the link and read the feature list at the top.

I haven't linked the page to the main list yet because it is still a little rough and I'm a new guy around here. I'm expecting some changes.

My schematic image looks worse than usual. It should be 640x480 but is being automatically resized somehow. Shouldn't this force the image size back to normal?
%width=640px% Attach:Thermistor4_Schematic.png

I think I have the external page formatting to something reasonable, but I haven't seen a document on the "official" internals (dealing with hidden code bits that link to the rest of the Playground). I've read quite a few docs but haven't seen something along the lines of "This is the internal code we do for the Playground". If there is one, please link it.

I've been using this code for months now and believe that most of the bugs have been ironed out. I could use some second opinions, though.

I've made provisions for external ADC's but don't have one hooked up to my "2009" board for testing. I also could use a little help there.

As a side note, my health sucks and I'm not very fast any more. I'm not able to monitor the forums 100% of the time. I have "excessively" documented this code for learning purposes and to help me remember what was done and why. If I'm not around to answer a question, someone please step in and help. I don't mind.
6  Forum 2005-2010 (read only) / Development / Re: Please Stick a list of arduino enabled chips :) on: October 02, 2010, 08:49:21 pm
I'd like to see more in the IDE. I've wondered why the more common and stable playground libraries haven't been included and the extra board/chip definitions (as mentioned earlier). Maybe those could be under some "contrib" type menu? Or is this a taboo subject? (remember I'm kinda new here)

Thankfully due to the help of others, this isn't too hard. :-)
7  Forum 2005-2010 (read only) / Development / Re: Please Stick a list of arduino enabled chips :) on: October 02, 2010, 05:58:30 pm
I have been doing a lot of work on the core files to enable them to support as many cpus as possible. Some of my changes have already been accepted for version 20. I hope some more of them will be as well. Here is a list of what I have working.

Thanks MarkS for having all these. I always knew Arduino had more, suspected there was more on top of those, but had no clue there were so many.

Part of the Arduino appeal for me is abstracting the lower layers as I don't handle that so well. I'd like to cast my vote to get more of these accepted into new releases.
8  Forum 2005-2010 (read only) / Interfacing / Re: Galvanic Vestibular Stimulation - AWESOME! on: August 29, 2010, 10:08:20 pm
This is the starting point of CES (which I use for stress management for my chronic sleep disorder):

I built my own since I researched the designs of others and considered them to be mediocre for the price. Someday I want to use an arduino connected to a computer with the OpenEEG project and have this dynamically controlled while I sleep.

I also figure an H-Bridge could turn that into a TENS unit.

One warning that is very important: people with epilepsy or a history of epilepsy in the family should be very careful to what they hook up to their heads. Needless to say, it could create a very bad situation. On the flip side, I have a theory that a CES unit could also control "uncontrollable" epilepsy if implemented correctly.
9  Forum 2005-2010 (read only) / Interfacing / Re: low pass filter resistor/capacitor values? on: October 17, 2010, 01:50:41 am
Keep in mind that an RC filter is NOT a brick wall filter. If you look at a plot of it, there will be a gentle slope off of the frequency.

Just did a quick check...
About 2/3 down the page they show the "step-response" graphs.

I'll reiterate what others have mentioned and add a little more.

* Since RC filters have a gentle slope... higher sampling rates will shift their DAC noise up in frequency and make the RC filters more effective. This is often called "oversampling" in the CD/DAC audio world. This won't help with RF noise, though.

* Motors are extremely noisy devices in the RF realm. The closer they are to an amp/signal wire, the more electrical noise there will be on the output. Shielding the motor will help a little but is usually more trouble than it's worth.

* Grounding and ground loops can be a royal PITA to clean up and fix. The simplest way is to use a star ground for everything, but this isn't always practical. If you're using a ground bus, put the high current and noisy stuff closest to the PSU ground. Digital stuff is just after that. Analog output is usually furthest away. Remember V=IR? Ground returns have a tiny resistance and high current pulses will show up as a voltage somewhere. If that somewhere is a sensitive amp, it will translate as noise into the output device.

* As a side warning, just about any side by side combination of resistor and capacitor will try to form some kind of pass filter. If you try stacking these, you will end up with a complex filter. I think this point is mostly irrelevant with an AVR+piezo, but it's worth mentioning for the archive.

* You can try adding PSU filter capacitors at strategic places, but make sure they are grounded properly (star ground preferred). See my grounding paragraph above.

* You can try adding filter inductors at strategic places, but do not use them in series with high current devices. I generally don't like inductors because they can become a short range antenna for the noise.

Just about everything on this list comes from what I've learned lurking on the audio forums. Didn't think I'd be using that knowledge here. smiley There are more complicated setups and explanations, but I think some combination of the above will help you. It's late and my eyes are crossing, but I think I hit on the major points of your problem. Good luck.
10  Forum 2005-2010 (read only) / Interfacing / Re: Arduino NTC thermistor test on: October 17, 2010, 12:51:15 am
Have a look at:

It will teach you about the equations, coefficients, and has some code to calculate the coefficients.  I did this with my 2 salvaged thermistors and it works very well so long as I use the full Steinhart-Hart equation.

You can also have a look at the library I added to the playground:

I have a lot of documentation in the source that will probably answer most questions.
11  Forum 2005-2010 (read only) / Interfacing / Re: Duemilenove + ArduinoISP cannot program 328p's? on: October 05, 2010, 05:27:46 pm
Thanks, that's a good link. Turns out it links back to the Playground. I added it to the page so it should help others in the future.
12  Forum 2005-2010 (read only) / Interfacing / Re: Duemilenove + ArduinoISP cannot program 328p's? on: October 04, 2010, 12:39:18 pm
In taking note of your clock comment, I also ran across this in my notes. When doing linux parallel port ICSP, udev doesn't seem to create an entry for my parallel port. I never figured this out, but the command is an easy fix:

mknod --mode=666 /dev/parport0 c 99 0

The permission bits are a bit open for my taste, but it usually isn't a problem for a single user system. Some laptop serial/parallel drivers are funky and need extra kernel drivers built in (like for my old Thinkpads). Keep an eye out for that.

I've considered making a dedicated FTDI cable for bit-bang mode, but this is very low on my priority list since my parallel cable works. I've seen the chips for about $5. It would probably be easier for now to just do the headers like you said. My finished project PCB I'm designing has an ICSP header on it so I shouldn't have to stress the 28pin DIP socket too much on my 2009 dev boards.

Did you end up doing your FTDI flash by command line? or the GUI mentioned in the earlier link?
If by command line, was it similar to this page?
Note the '!' has to be present for that link to work.
If it was different, would you mind posting your commands for the record?
13  Forum 2005-2010 (read only) / Interfacing / Re: Duemilenove + ArduinoISP cannot program 328p's? on: October 03, 2010, 08:31:34 pm
Glad things worked out. :-)

I've been curious to try FTDI bit-bang and "Arduino as ISP", but my parallel cable has worked nicely for ICSP. Since I'm running linux, I'd have to learn the manual avrdude syntax for the FTDI method... and that scares me a little. It's moving up on the list, though, as parallel ports disappear.

For the future record of someone searching the archives... It's my understanding that "Burn Bootloader" from the IDE menu will properly set the FUSE bits on a virgin or semi-trashed AVR and then flash the bootloader. This is what I was comparing in my previous post using avrdude between my two mentioned AVR's (and they matched perfectly).

I've also had some scary experiences pulling chips out of sockets. I don't have a chip puller, so I just use a small flat blade screwdriver. Way back I learned the trick: as the screwdriver nears the end of the chip, hold down the blade flat against the socket, hold down the already pryed up end of the chip against the screwdriver shaft, and gently rock it back to pry up the final end. As many have already noted, DIP sockets aren't intended for mass usage, but one can get away with periodic usage like this.
14  Forum 2005-2010 (read only) / Interfacing / Re: Duemilenove + ArduinoISP cannot program 328p's? on: October 02, 2010, 07:52:06 pm
I know very little about avrdude commands, but here is my experience with SparkFun...

I "supposedly" bought a preflashed ATmega328 from SparkFun as a backup, but it also had problems. I ended up making the ICSP parallel cable and manually flashing it.

I swapped it into my "2009" board for all the work. After the parallel port ICSP flashing, it seemed to be OK.

My P4 system could then use the serial flash upload for sketches from the IDE. If I moved it over to my Phenom system, it BARFS BADLY. If I swapped back in the ATmega328 that came with the "2009" board, it "mostly" works... but the Phenom is cranky where my older P4 is not.

I haven't been able to figure out why the Phenom has such problems. I've tried different USB cables on different ports directly plugged into the motherboard. I also compiled and replaced avrdude that comes with 0019. Nothing makes any difference. I don't use USB much, but my MP3 player and my card reader have never had any problems.

So... based on my experience, I'd recommend trying to flash in an official Arduino board with NOTHING else hooked up just for simplicity's sake. Try flashing the ATmega328 that came with the Arduino (that is, a non-SparkFun AVR) just to see if it responds. I'd also recommend trying a different computer just to see what happens. Maybe something would show up.

To compare my 2 AVR's, this is the command I used (swapping them in the "2009" board):

cd <ARDUINO>/hardware/tools
./avrdude -C ./avrdude.conf -p m328p -c dapa -P /dev/parport0 -v

(obviously I'm linux and your windoze, but I think you can figure out the differences)

I'd recommend trying to get the read to work before the write (which kinda looks like what you're doing).

I noticed your command lacked the "-C avrdude.conf" file. That might make some difference.

From there, I'm out of ideas. Hopefully someone else can add something. Good luck.
15  Forum 2005-2010 (read only) / Frequently-Asked Questions / A quick word of warning on: August 24, 2010, 10:15:57 pm
I found an old bottle of muratic acid in the garage and used it as an etchant as already mentioned. It worked very well for exposed copper, but my paper stock had problems with the toner transfer part.

A quick warning: I'm not sure if there was some evaporation/concentration over the years, but when I transferred it to a leak proof bottle when done (the original plastic bottle was having issues), it was still outgassing a little. IT NEARLY EXPLODED THE PLASTIC BOTTLE. I'm very thankful I avoided true disaster with that.

Moral of the story: leave the lid mostly closed but allow for a little gas to escape the first day. A flip top plastic bottle (like some vinegar bottles I've seen) may also be a good choice.
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