http://www.opencircuits.com/api.php?action=feedcontributions&user=194.176.176.82&feedformat=atomOpenCircuits - User contributions [en]2024-03-29T12:30:09ZUser contributionsMediaWiki 1.34.2http://www.opencircuits.com/index.php?title=Passives&diff=16988Passives2008-12-16T18:48:10Z<p>194.176.176.82: FIELD_OTHER</p>
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<div>FIELD_MESSAGE_crelsitlatrz</div>194.176.176.82http://www.opencircuits.com/index.php?title=PG31_GPS_USB_Dev_Board&diff=16982PG31 GPS USB Dev Board2008-12-16T18:21:18Z<p>194.176.176.82: FIELD_OTHER</p>
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<div>{| align=right<br />
|-<br />
| <br />
[[Image:Main-Eval-PG31-USB-Loaded.jpg|PG31 USB Dev Board]]<br />
|}<br />
<b>Description:</b><br> You've probably heard about the CP210x USB ICs from Silicon Labs, now here's an application that uses it. The CP2102 gives us 3V TTL to a VCP (virtual comm port) over USB as well as generating the 3.3V needed for the board.<br />
<br />
In this project we demonstrate how to:<br />
*Setup a USB to Serial link<br />
*Use the CP2102 for 3.3V<br />
*Use a SMD 12mm battery holder<br />
<br />
----<br />
===USB Connection===<br />
The CP2102 USB IC is fairly easy to use once you've plugged it down a couple times. <br />
<br />
[[Image:PG31-USB-Connection.jpg|PG31 USB Connection]]<br />
<br />
The USB connector has four pins : Vcc (*around* 5V), GND, D+, D-. Tying these four connections to the CP2102 is easy enough.<br />
<br />
[[Image:PG31-USB-Connection-Schematic.jpg]]<br />
<br />
There are a couple things to note. In this setup, we do not have any ESD protection or surge supression. We are quite possibly violating some USB standards. But does it work? Yep.<br />
<br />
When you configure the CP2102 this way, it can source up to 100mA at 3.3V using its internal voltage regulator. This is perfect for our application as the PG31 needs ~40mA at 3.3V. <br />
<br />
Note the TX pin on the CP2102 is an output and needs to be connected to the RX pin on the PG31. This screwed me up a few times. <br />
<br />
The CP2102 has built-in cystal and eeprom. These means you need very few external components to get it working. You can even program in your own ID string so when you plug it onto your computer, it comes up with the name of your widget!<br />
<br />
When the CP210x is attached to a computer (and it's soldered correctly) you will see windows hardware wizard request drivers. These drivers can be downloaded from SI Labs. You can also create ''your own signature drivers'' using some SI Labs software. <br />
<br />
You can also program the internal EEPROM to reflect your own product ID and serial strings. This software is from SI Labs as well but I forget were - when someone finds it, post it here.<br />
<br />
Once the drivers are installed, the CP210x will turn into a serial com port! Yes! It's weird to think about until you see it happen. So this USB dev board now acts like a com port on my computer. All I have to do is pass characters in and out COM 5 (for example) and I can do things over USB! No messy drivers, no protocols to think about, it's all done in the IC. All right!<br />
<br />
One thing to note when you are using the CP210x ICs, the Linux community may scoff. SI Labs did a great job with the windows support, but a piss-poor job of opening the drivers for the open-source community. I'm not really a Linux person so it didn't effect me. But if your app needs linux connectivity, you may want to take a quick look for other potential ICs. Last I heard, there was good Linux support for the CP2102, but there was nothing for the CP2103 GPIO control...<br />
<br />
One last con : The ICs come in QFN leadless package only. YES it can be soldered by hand, but you'll need some experience and/or some good hot-air soldering tools. I taught myself how to rework stuff using this IC. You really can't destroy it, but you can certainly delaminate (kill) the PCB if you heat it for excessive amounts of time. Don't 'not' create a PCB or a design because of silly SMD parts. They're not that hard to solder!<br />
<br />
----<br />
<br />
===Battery Backup===<br />
<br />
[[Image:12mm-Holder.jpg|12mm coin cell holder]]<br />
<br />
If you're playing with GPS, you've ''got to have a battery backup''. The 12mm coin cell lithium allows the PG31 (and many other GPS receivers) to retain the alamanac data. This small battery provides just enough juice for 3-5 years. By having alamanac data at power on, the GPS receiver will be able to do a warm lock instead of a cold lock. Cold locks take 1-2 minutes, warm locks, as little as 30 seconds. The alamanac data, in effect, allows the GPS receiver to 'guess' where it is in the world ("Last time I was on I was in Ohio, therefor, I will assume I'm near there").<br />
<br />
If you're unfamiliar with Lithium Coin Cells - they come in a couple different sizes. I prefer 12mm just cause it's small but beefy enough to do most of the BBR (battery backed ram) that we need to support. The battery itself has a postive top (noted by the plus) and a ground on the bottom. You normally create a pad on the PCB for the ground and the coin cell holder is positive. We've learned the hard way that the bottom part of the cell is sometimes concave. This means that when you slide the coin cell onto the board, the concave ground part of the cell may not contact the PCB pad very well. If you're using a paste stencil, just leave a cutout for this pad. The extra paste will add 5-10 mils of solder to the pad. If you're solder the thing by hand, add a little blob of solder to this ground pad to give it some height. When you insert the battery, it should ride nicely on top of the ground pad blob.<br />
----<br />
===PG31 Footprint===<br />
[[Image:PG31-Footprint.jpg]]<br />
<br />
Now about the footprint for the PG31. Unless the manufacturer hands you a foorprint file or a simple, recommended FP in the datasheet, you're going to have to go it on your own. We took the PG31 and a pair of calipers and went at it. It can be extremely difficult the first time. This PG31 FP took me twice to get correct. Do the best you can and try to account for things like the antenna connector. The second rev FP, I forgot to account for the MMCX connector, I put the DB9 connector right up against the PG31, and Viola - useless PCB! a.k.a another coaster for my coffee cup. But once you've got the FP, you're good for all future projects using that device. Now you know when engs hate to change parts...<br />
<br />
----<br />
FIELD_MESSAGE_delcnat<br />
<br />
===Things to Improve===<br />
So that's pretty much it. The board works well, and assuming Laipac doesn't change their parts again, we will produce the board for some time.<br />
<br />
We may consider migrating to a different USB IC someday but the CP2102 continues to be a really simple to use USB to UART IC.<br />
----<br />
==Documents==<br />
[[Media:PG31 USB Schematic.pdf|PG31 USB Schematic]]<br />
<br />
[[Media:PG31 USB Carrier - Protel.zip|PG31-USB Protel File]]<br />
<br />
[[Media:PG31 USB Carrier - Gerbers.zip|PG31-USB Gerber Files]]<br />
<br />
<b>Footprints:</b><br><br />
[[SFE_Footprint_Library|SFE Footprint Library]]<br />
<br />
FP Name: PG31<br />
<br />
<b>Supplier Info:</b><br />
Spark Fun Electronics part # : Eval-PG31-USB<br><br />
Single Piece Price : $29.95<br />
<br />
<b>Related Items:</b><br />
<br />
* [[PG31 GPS RS232 Dev Board]]<br />
<br />
[[Category:Projects]]</div>194.176.176.82http://www.opencircuits.com/index.php?title=Talk:PG31_GPS_RS232_Dev_Board&diff=16979Talk:PG31 GPS RS232 Dev Board2008-12-16T17:04:22Z<p>194.176.176.82: New section: FIELD_OTHER</p>
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<div><br />
== discussion ==<br />
<br />
== FIELD_OTHER ==<br />
<br />
FIELD_MESSAGE_boacelcopa</div>194.176.176.82http://www.opencircuits.com/index.php?title=User:DavidCary&diff=16975User:DavidCary2008-12-16T16:20:21Z<p>194.176.176.82: FIELD_OTHER</p>
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<div>Welcome to my little corner of Open Circuits.<br />
<br />
I think I first stumbled across Open Circuits on 2006-03-01.<br />
I had been starting to set up a electronics-related wiki,<br />
but since this one was already here, why bother?<br />
<br />
Feel free to leave a note on [[User_talk:DavidCary|my talk page]].<br />
<br />
I created the [[WikiNode]].<br />
<br />
Electronic projects:<br />
''(Should I move these to dedicated pages such as [[electronics workbench]], etc.?)''<br />
<br />
== wind turbine maximum power point tracker ==<br />
<br />
''moved to [[maximum power point tracker]]''<br />
<br />
== anti-spam ==<br />
<br />
see [[spam]].<br />
<br />
I prefer public communication so I avoid the problems associated with (the perception of) [http://www.usemod.com/cgi-bin/mb.pl?BackRoomDecision back room decision]s.<br />
<br />
--[[User:DavidCary|DavidCary]] 18:03, 4 February 2008 (PST)<br />
<br />
== electronics workbench ==<br />
<br />
What exactly do I need for "normal" electronics development?<br />
I have a pile of stuff, and I have a wishlist of more stuff ...<br />
I hope to document which things are important to have, which things are useful but not immediately necessary, and which things ended up just gathering dust.<br />
<br />
I wish there were a place like [http://blog.guykawasaki.com/2007/09/techshop-geek-h.html TechShop] somewhere local.<br />
<br />
* filing cabinet for all the miscellaneous bits of paper. If at all possible, I attach instruction manuals to the actual tool -- but if that is awkward, I stick the instruction manual in this filing cabinet.<br />
<br />
== data collection network ==<br />
<br />
I'm building a "data collection network" that may end up with hundred of microcontroller sensor nodes,<br />
piping data into a PC.<br />
This may turn into a serious medical diagnosis tool.<br />
<br />
== POV display ==<br />
<br />
''(moved to [[POV display]])''<br />
<br />
== Full-color LED lighting ==<br />
<br />
I'm planning to build a silly little toy with 3 LEDs -- one for red, green, and blue --<br />
to show how "additive colors" work (a "color wheel").<br />
(I might just extend it to have a whole spectrum of visible and infrared LEDs, and a prism to show the little spikes in the spectrum that LEDs generate).<br />
<br />
"Red, Green, and Blue LED based white light generation"<br />
by Muthu, Schuurmans, and Pashley (2002)<br />
http://www.advancetransformer.com/uploads/resources/LED_White_Light_Issues&Control_-_White_paper.pdf<br />
<br />
LED illumination applications<br />
http://en.wikipedia.org/wiki/Light-emitting_diode#Illumination_applications<br />
<br />
"How Many Red, Green, and Blue LEDs to make White"<br />
by Don Klipstein 2001<br />
http://members.misty.com/don/ledrgb2w.html<br />
<br />
LED Color Shifting<br />
http://hackedgadgets.com/2006/02/14/wireless-led-color-shifting/<br />
<br />
FIELD_MESSAGE_acelal<br />
<br />
== Open Circuits Sysop ==<br />
<br />
Whee! I'm a sysop at Open Circuits!<br />
The power -- it's rushing to my head!<br />
--[[User:DavidCary|DavidCary]] 15:20, 23 February 2007 (PST)<br />
<br />
Me too ( thanks to you? ). How can I use my power, release the hounds. I am open to suggestions as to how I can help, right now I am just going to read up on what a sysop can do. [[russ_hensel]] Feb '08<br />
<br />
<br />
Hi David, will be nice to have antispam measures :).<br />
<br />
--[[User:RafaelOrtiz|RafaelOrtiz]] 18:00, 28 October 2007 (PDT)<br />
<br />
Hi David can you give me some block IP rights ? <br />
<br />
--[[User:RafaelOrtiz|RafaelOrtiz]] 13:17, 18 November 2007 (PST)<br />
<br />
Hi David, I noticed that a bunch of open circuits is just a placeholder. I'm effectively retired so I can probably help contribute to this Wiki by expanding a bunch of the sections, but the spam here is really way out of control. I look at the revision history and I see a good 10+ spam edits per day. Don't you think it's time to try requiring a logon to make edits? I thank that would really reduce the spam. Asking people to use a human controlled e-mail address is not that much. It's not like people need to give their real name and address or anything. I think you will find that more people will be willing to contribute if the spam problem is handled. Eliminating the spam is more of a problem at this point then getting people to contribute. It would also free up your time to focus more on real editing.<br />
[[User:Mzoran|Mzoran]] 19:38, 12 December 2007 (PST)<br />
<br />
== strange and bizarre serial protocols ==<br />
<br />
It seems like many people can't resist building yet another custom proprietary communication protocol.<br />
I'm polishing up a list of the 22 most common serial communication problems.<br />
I'm also making a collection of various communication protocols.<br />
I'm most interested in protocols that are (a) simpler to implement and simpler to understand than TCP/IP, (b) don't use "too many" pins on a microcontroller, and (c) avoid most of the above 22 most common problems.<br />
<br />
I am beginning to suspect that it may not be possible to avoid all 22 problems unless the protocol is at least as complex as TCP/IP.<br />
<br />
Also, I think that 4 pins on the microcontroller seems to make the hardware and software the simplest -- it's possible to squeeze communication to fewer pins, but either the hardware or the software (or both) will be more complicated.<br />
<br />
Some "simple" protocols:<br />
* [[SPI]]<br />
* [http://www.microchip.com/unio UNI/O single I/O serial bus] -- seems to contradict my earlier suspicion -- the hardware is simple (connect a I/O pin on the MCU directly to the I/O pin on the EEPROM), and the software doesn't seem very complex.<br />
* ... more to come ...</div>194.176.176.82http://www.opencircuits.com/index.php?title=Chemical_Etchants&diff=16973Chemical Etchants2008-12-16T16:11:46Z<p>194.176.176.82: acgetboc</p>
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<div>delbocnod<br />
{{stub}}<br />
<br />
After masking off the parts of the copper-clad board you want to keep, you need to remove the parts you don't want to keep. This is usually done by chemically etching away the copper. There are a lot of different chemical techniques for doing this, each with its own advantages and drawbacks.<br />
<br />
None of these chemicals is incredibly dangerous, but they can all be toxic or caustic, and should be treated with care. Eye protection and gloves are a very good idea. Before you start, make sure you know how dangerous each chemical is, and figure out what you will need to do if you spill it or get it on yourself. Washing with plenty of water is usually a good start. For some chemicals you may want to keep a neutralizing agent handy. An MSDS (Materials Safety Data Sheet) for the chemical will give you some basic information.<br />
<br />
== Ferric Chloride ==<br />
This is the most common hobbyist etchant. Ferric chloride, FeCl<sub>3</sub>, is a brownish substance. It's usually sold in a bottle (dissolved in water, perhaps with a little acid or peroxide) or as a powder (which you have to dissolve in water).<br />
<br />
When in solution, ferric chloride is a ferric ion (Fe<sup>3+</sup>) and a chloride ion (Cl<sup>-</sup>). The ferric ion reacts with the metallic copper on the circuit board in a redox reaction, producing a ferrous ion (Fe<sup>2+</sup>) and cuprous or cupric (Cu<sup>1+</sup> or Cu<sup>2+</sup>) copper. The chlorine is just along for the ride. The copper ion, unlike the metallic copper, is soluble, so it leaves the circuit board and goes into solution. The reaction products form a black sludge which settles to the bottom of the etching tank. After etching enough copper, all your Fe<sup>3+</sup> is used up and your solution is full of Cu<sup>1+</sup>, and you need to get more etchant.<br />
<br />
== Ammonium Persulfate ==<br />
Expensive & hard to control and optimize the process parameters (such as specific gravity & pH value).<br />
<br />
== HydroChloric Acid / Hydrogen Peroxide ==<br />
<br />
Mixing about 1 part HCl (Which can be found at most hardware stores, also known as Muriatic Acid. Ask for concrete cleaner.) into 2 parts Hydrogen peroxide (normally used for cleaning cuts) you can make a fairly powerful etchant. Use gloves and don't breathe the fumes though. This will etch a 3"x5" board in less than 10 minutes. No need to heat it up. I usually like to drill a small hole through the board on a corner and thread a wire or nylon string through to help agitate / remove the board.<br />
<br />
When the board is done etching, the etchant will probably look like green kool-aid, from the copper content in it. This stuff is highly corrosive and will burn skin, which is why you should wear gloves. But it is easy to handle, and fairly easy to dispose of. the etchant is easily deactivated with baking soda. Pour enough baking soda into it slowly (to keep it from boiling and overflowing... remember what happens with baking soda/vinegar? ya...) until it is a solid mass, then leave it in the sun to dry. You should contact your local authorities to find out what you should do with it next. Whatever you do, DO NOT dump the stuff down the drain, it will eat through your pipes just like any of the other etchants.<br />
<br />
Alternatively, instead of disposing of the etchant, you can re-use it again and again. In fact, after etching a few boards with this solution, you will have successfully made [[Chemical Etchants#Acid Cupric Chloride|Acid Cupric Chloride]] (see below).<br />
<br />
== Sodium Persulfate ==<br />
More environmentally friendly than ferric chloride. Can monitor the etching as initially clear new etchant solution turns blue from the copper ions.<br />
<br />
== Acid Cupric Chloride ==<br />
Dead simple etchant made from ordinary, store-bought chemicals (hydrochloric acid and hydrogen peroxide). Has the advantage that it can be regenerated by bubbling oxygen/air through it, or by adding more H<sub>2</sub>O<sub>2</sub>. In addition, it doesn't get used up: the etchant bath simply grows with use (kind of like sourdough starterâ¦)<br />
The used etchant also makes a great algecide/pH reducer for your pool (and a whole lot cheaper than that stuff they sell at the pool store).<br />
<br />
What you need:<br />
* 38% Hydrochloric Acid, HCl (available at finer hardware stores or pool supply stores as Muriatic Acid)<br />
* 3% Hydrogen Peroxide, H<sub>2</sub>O<sub>2</sub> (available from any drug store)<br />
* Plastic or Glass Pans, Jars, and tongs (no metal)<br />
Directions:<br />
<br />
# Mix your HCl and H<sub>2</sub>O<sub>2</sub> 1:1 in a non-metalic container, making sure to add the acid slowly to the H<sub>2</sub>O<sub>2</sub>. DO NOT ADD THE H<sub>2</sub>O<sub>2</sub> TO THE ACID!!! <br />
# After you've masked your board, dip it in the solution and constantly agitate. You should notice a dark green cloud start to come from the board almost immedately which quickly dissapears or turns lighter as it gets further from the surface of the board.<br />
# Etching should take about 10min depending on the temperature and how well you agitated the etchant. When all of the copper is gone, dip in water to wash off any stray etchant and stop the reaction.<br />
# When done etching, save used etchant in a non-metalic container and mark clearly its contents.<br />
# If your etchant has become a dark, murky green color, add a little bit of H<sub>2</sub>O<sub>2</sub> or bubble air/O<sub>2</sub> through the solution to regenerate it back to a light, transparent green color.<br />
See links at bottom for more information on the chemistry and some pictures of the process.<br />
<br />
== Disposal procedures ==<br />
Flushing used etchant down the drain is a bad idea (and usually illegal) because copper ion is toxic. The usual recommended way to dispose of hobbyist amounts of etchant is to convert it to a solid somehow and dispose of the solid in the trash.<br />
* [http://www.kepro.com/fmc4.htm Kepro Circuit Systems] Removal of Copper and Persulfate from Spent Sodium Persulfate Etchant by Precipitation<br />
<br />
== External Links == <br />
* [http://www.k9spud.com/wiki/PCB:Etchants Ferric Chloride vs. Ammonium Persulfate] and other etching chemicals.<br />
* [http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html Etching with Air Regenerated Acid Cupric Chloride] â an excellent in-depth page on acid cupric chloride etching by Adam Seychell.<br />
* [http://esmonde-white.com/etching_pcb.html Etching a Copper PCB with HCl and H2O2]<br />
*[http://www.mgchemicals.com/index.html MG Chemicals]A possible source?<br />
<br />
== Internal Links ==<br />
<br />
<br />
*[[Toner Transfer]]<br />
*[[Techniques]]<br />
*[[Eagle Links]]<br />
<br />
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[[Category:Techniques]]</div>194.176.176.82