Difference between revisions of "PG31 GPS USB Dev Board"

From OpenCircuits
Jump to navigation Jump to search
m (Reverted edits by 194.176.176.82 (Talk); changed back to last version by 193.51.215.2)
 
(58 intermediate revisions by 33 users not shown)
Line 1: Line 1:
[http://trumanburb.ifrance.com/view/new/x-i.htm x5 i audio] [http://joshuaw-wise.ifrance.com/img/styles/sony-cybershot/ sony cyber-shot dsc v3] [http://dejablu503.ifrance.com/description/lib/km-mercedes.htm km0 mercedes classe a 180 auto km 0] [http://krychan.ifrance.com/content/view/ravenna-imer.htm ravenna imer] [http://cocopuff66.ifrance.com/text/directory/reflex-digitale/ reflex digitale obiettivi] [http://call-shotgun.ifrance.com/view/new/tuffa-tider/ tuffa tider] [http://squoi-oop.ifrance.com/topic/ram-aspire/ ram aspire] [http://flawedamythyst.ifrance.com/img/styles/storia-damore.htm storia damore con i crampi] [http://zeakk.ifrance.com/resources/articles/traduzione-di.htm traduzione di tiziano ferro breathe easy] [http://atrayah.ifrance.com/topic/aziende-musicali.htm aziende musicali] [http://mfirishka.ifrance.com/view/new/bmw-firenze.htm bmw firenze] [http://nokros.ifrance.com/data/divx-rete/ divx rete] [http://nokros.ifrance.com/data/processori-amd/ processori amd fx] [http://joshuaw-wise.ifrance.com/img/styles/meture-free/ meture free] [http://alishca-st.ifrance.com/text/directory/hotel-a.htm hotel a siviglia] [http://lightmyfire0214.ifrance.com/topic/beautiful-shadow/ beautiful shadow] [http://gabe95.ifrance.com/html/dragon-figth/ dragon figth] [http://gabe95.ifrance.com/html/sesso-selvaggio/ sesso selvaggio] [http://lightmyfire0214.ifrance.com/topic/infopoint/ infopoint] [http://cocopuff66.ifrance.com/text/directory/www-flou/ www flou it] [http://zeakk.ifrance.com/resources/articles/puntorosso-net.htm puntorosso net] [http://flawedamythyst.ifrance.com/img/styles/tower-dvd.htm tower dvd] [http://sm4.ifrance.com/lib/wrestler/ wrestler] [http://gabe95.ifrance.com/html/canali-radio/ canali radio] [http://lekusya.ifrance.com/library/html/elster/ elster] [http://joshuaw-wise.ifrance.com/img/styles/orlando-innamorato/ orlando innamorato] [http://dejablu503.ifrance.com/description/lib/coover-cd.htm coover cd] [http://gabe95.ifrance.com/html/www-grandefratelo/ www grandefratelo] [http://squoi-oop.ifrance.com/topic/soundtrack-di/ soundtrack di grease] [http://lightmyfire0214.ifrance.com/topic/mellin-progress/ mellin progress] [http://trumanburb.ifrance.com/view/new/foder-cona.htm foder cona] [http://alishca-st.ifrance.com/text/directory/macrovision.htm macrovision] [http://flawedamythyst.ifrance.com/img/styles/scart-g.htm scart g bl] [http://cocopuff66.ifrance.com/text/directory/www-leoni/ www leoni dellanotte com] [http://squoi-oop.ifrance.com/topic/grossisti-argento/ grossisti argento] [http://krychan.ifrance.com/content/view/www-ulss.htm www ulss5 it] [http://smegmacheez.ifrance.com/content/view/un-grande/ un grande amore e niente piu] [http://atrayah.ifrance.com/topic/il-fornaretto.htm il fornaretto di venezia] [http://gajar.ifrance.com/html/compatibile-hp.htm compatibile hp] [http://alishca-st.ifrance.com/text/directory/premi-tesi.htm premi tesi laurea] [http://gajar.ifrance.com/html/nvgs.htm nv-gs 17] [http://horcrionebay.ifrance.com/resources/articles/opel-vectra.htm opel vectra 2001] [http://cocopuff66.ifrance.com/text/directory/diaframmare/ diaframmare] [http://gajar.ifrance.com/html/ordine-economico.htm ordine economico e ordinamento giuridico] [http://trumanburb.ifrance.com/view/new/video-snowboard.htm video snowboard] [http://atrayah.ifrance.com/topic/memoria-ram.htm memoria ram 128 mb] [http://gajar.ifrance.com/html/mamme-gratis.htm mamme gratis] [http://dejablu503.ifrance.com/description/lib/sim-card.htm sim card] [http://nokros.ifrance.com/data/volo-buenos/ volo buenos aires] [http://mfirishka.ifrance.com/view/new/lettore-dvd.htm lettore dvd e mp3 portatile] [http://atrayah.ifrance.com/topic/manic-monday.htm manic monday bangles] [http://atrayah.ifrance.com/topic/box-ide.htm box ide usb] [http://atrayah.ifrance.com/topic/monitor-pc.htm monitor pc 17] [http://flawedamythyst.ifrance.com/img/styles/parlapiano.htm parlapiano] [http://gabe95.ifrance.com/html/lettino-baby/ lettino baby expert] [http://krychan.ifrance.com/content/view/zhanjiang.htm zhanjiang] [http://trumanburb.ifrance.com/view/new/senos-de.htm senos de la artista cristina aguilera] [http://lekusya.ifrance.com/library/html/cannabis-sativa/ cannabis sativa l] [http://lightmyfire0214.ifrance.com/topic/armadillo-kinght/ armadillo kinght] [http://dejablu503.ifrance.com/description/lib/offerta-regali.htm offerta regali frosinone] [http://flawedamythyst.ifrance.com/img/styles/jaguar-s.htm jaguar s type 2 5] [http://cocopuff66.ifrance.com/text/directory/articolo-giardinaggio/ articolo giardinaggio] [http://zeakk.ifrance.com/resources/articles/casa-albergo.htm casa albergo] [http://sm4.ifrance.com/lib/d-ft/ d12 ft eminem salsa] [http://nokros.ifrance.com/data/volo-aereo/ volo aereo venezia lampedusa] [http://nokros.ifrance.com/data/titan-force/ titan force] [http://squoi-oop.ifrance.com/topic/sex-japan/ sex japan] [http://nokros.ifrance.com/data/samsonite-oyster/ samsonite oyster] [http://atrayah.ifrance.com/topic/lcd-.htm lcd 17 philips 170s5fg] [http://smegmacheez.ifrance.com/content/view/sony-ke/ sony ke p37m1] [http://trumanburb.ifrance.com/view/new/canon-a.htm canon a95] [http://smegmacheez.ifrance.com/content/view/garota-de/ garota de ipanema] [http://horcrionebay.ifrance.com/resources/articles/hit-mania.htm hit mania dance summer] [http://horcrionebay.ifrance.com/resources/articles/opel-corsa.htm opel corsa viva 1.2] [http://squoi-oop.ifrance.com/topic/giochi-schiaccia/ giochi schiaccia tutto] [http://atrayah.ifrance.com/topic/quel-tipo.htm quel tipo di donna] [http://flawedamythyst.ifrance.com/img/styles/prime-immagini.htm prime immagini per fifa street 2 su ds] [http://cocopuff66.ifrance.com/text/directory/globalsat-bt/ globalsat bt338 sirf star iii bluetooth] [http://sm4.ifrance.com/lib/gusto-latino/ gusto latino] [http://atrayah.ifrance.com/topic/alcor-indiana.htm alcor indiana line] [http://atrayah.ifrance.com/topic/gelas.htm gelas] [http://flawedamythyst.ifrance.com/img/styles/prostitutas-de.htm prostitutas de lima com] [http://gajar.ifrance.com/html/pioneer-vsxdk.htm pioneer vsx-d514-k] [http://alishca-st.ifrance.com/text/directory/finanziamento-berlino.htm finanziamento berlino] [http://atrayah.ifrance.com/topic/bmw-k.htm bmw k 1100] [http://atrayah.ifrance.com/topic/gazzelloni.htm gazzelloni] [http://dejablu503.ifrance.com/description/lib/wrestling-pc.htm wrestling pc] [http://flawedamythyst.ifrance.com/img/styles/marcie-sinfoniche.htm marcie sinfoniche] [http://nokros.ifrance.com/data/smallrockets-backgammon/ smallrockets backgammon] [http://zeakk.ifrance.com/resources/articles/news-costantino.htm news costantino] [http://krychan.ifrance.com/content/view/patrizia-de.htm patrizia de blank] [http://joshuaw-wise.ifrance.com/img/styles/toshiba-satellite/ toshiba satellite m30x] [http://dejablu503.ifrance.com/description/lib/soppalco-it.htm soppalco it] [http://gabe95.ifrance.com/html/alessandra-matera/ alessandra matera] [http://trumanburb.ifrance.com/view/new/lofra-cucine.htm lofra cucine] [http://zeakk.ifrance.com/resources/articles/citroen-c.htm citroen c3 pluriel] [http://horcrionebay.ifrance.com/resources/articles/accordo-poste.htm accordo poste oo ss del 13 01 2006] [http://gajar.ifrance.com/html/icm.htm icm] [http://gajar.ifrance.com/html/jimmy-neutro.htm jimmy neutro] [http://horcrionebay.ifrance.com/resources/articles/suocere-.htm suocere  troie] [http://gajar.ifrance.com/html/vlformdesigner.htm vlformdesigner] [http://squoi-oop.ifrance.com/topic/maiori-casa/ maiori casa appartamento] [http://mfirishka.ifrance.com/view/new/luis.htm luis 14] [http://cocopuff66.ifrance.com/text/directory/pallone/ pallone 2002] [http://call-shotgun.ifrance.com/view/new/mandy-smith/ mandy smith] [http://smegmacheez.ifrance.com/content/view/marmitta-scooter/ marmitta scooter] [http://call-shotgun.ifrance.com/view/new/utenti-italgas/ utenti italgas online] [http://trumanburb.ifrance.com/view/new/you-don.htm you don t have to sayu] [http://call-shotgun.ifrance.com/view/new/sitecom-portable/ sitecom portable] [http://sm4.ifrance.com/lib/il-grande/ il grande silencio] [http://alishca-st.ifrance.com/text/directory/ambient-light.htm ambient light 3d - skin default] [http://nokros.ifrance.com/data/lcd-pf/ lcd 15pf7846] [http://call-shotgun.ifrance.com/view/new/is-it/ is it cos i m cool video] [http://gabe95.ifrance.com/html/dvd-dvx/ dvd dvx recorder hard disk] [http://flawedamythyst.ifrance.com/img/styles/gioco-pinguino.htm gioco pinguino] [http://zeakk.ifrance.com/resources/articles/battlefield-.htm battlefield 2 dal 21 giugno] [http://atrayah.ifrance.com/topic/kupa.htm kupa] [http://trumanburb.ifrance.com/view/new/hd-usb.htm hd usb lacie] [http://squoi-oop.ifrance.com/topic/lupin-arriva/ lupin arriva in sala giochi] [http://lightmyfire0214.ifrance.com/topic/ufficio-medico/ ufficio medico legale cagliari] [http://squoi-oop.ifrance.com/topic/apertura-tube/ apertura tube di falloppio] [http://flawedamythyst.ifrance.com/img/styles/lettore-x.htm lettore x memory] [http://flawedamythyst.ifrance.com/img/styles/regione-valled.htm regione valled aosta] [http://trumanburb.ifrance.com/view/new/tomtom-navigator.htm tomtom navigator 5 gps bluetooth] [http://call-shotgun.ifrance.com/view/new/quartiere/ quartiere] [http://nokros.ifrance.com/data/lao-cai/ lao cai] [http://atrayah.ifrance.com/topic/signor-moia.htm signor moia] [http://alishca-st.ifrance.com/text/directory/campoformio.htm campoformio] [http://joshuaw-wise.ifrance.com/img/styles/adsl-firewall/ adsl firewall router] [http://horcrionebay.ifrance.com/resources/articles/campion-calcio.htm campion calcio] [http://flawedamythyst.ifrance.com/img/styles/missale-libri.htm missale libri] [http://dejablu503.ifrance.com/description/lib/tom-tom.htm tom tom 5 0] [http://call-shotgun.ifrance.com/view/new/fiatgroup/ fiatgroup] [http://sm4.ifrance.com/lib/dvd-r/ dvd r registrabili] [http://alishca-st.ifrance.com/text/directory/lu-colombo.htm lu colombo and maracaibo] [http://horcrionebay.ifrance.com/resources/articles/juegos-pornos.htm juegos pornos] [http://gabe95.ifrance.com/html/orologio-polso/ orologio polso vendita] [http://lightmyfire0214.ifrance.com/topic/sogni-di/ sogni di rock] [http://call-shotgun.ifrance.com/view/new/serigrafi-barkod/ serigrafi barkod] [http://cocopuff66.ifrance.com/text/directory/ilpoggio/ ilpoggio] [http://sm4.ifrance.com/lib/ironweed/ ironweed] [http://zeakk.ifrance.com/resources/articles/km-volvo.htm km0 volvo xc90 auto km 0] [http://smegmacheez.ifrance.com/content/view/napule-e/ napule e na canzone] [http://squoi-oop.ifrance.com/topic/zhenhai/ zhenhai] [http://zeakk.ifrance.com/resources/articles/tigra.htm tigra 1999] [http://cocopuff66.ifrance.com/text/directory/il-ladro/ il ladro dei bambini] [http://sm4.ifrance.com/lib/vesna-pisarovic/ vesna pisarovic mp3] [http://lekusya.ifrance.com/library/html/milano-sharm/ milano sharm el sheikh biglietti aerei] [http://dejablu503.ifrance.com/description/lib/emporio-armani.htm emporio armani occhiali uomo da sole] [http://smegmacheez.ifrance.com/content/view/kitchener/ kitchener] [http://horcrionebay.ifrance.com/resources/articles/celebrita-a.htm celebrita a piedi nudi] [http://lekusya.ifrance.com/library/html/a-bt/ a620 bt gps asus palmari] [http://dejablu503.ifrance.com/description/lib/clarion-autoradio.htm clarion autoradio] [http://trumanburb.ifrance.com/view/new/miu-olympus.htm miu olympus] [http://alishca-st.ifrance.com/text/directory/sunrise-feel.htm sunrise feel like home] [http://flawedamythyst.ifrance.com/img/styles/leasing-auto.htm leasing auto] [http://joshuaw-wise.ifrance.com/img/styles/metafonia/ metafonia] [http://lightmyfire0214.ifrance.com/topic/iguana-dalla/ iguana dalla lingua di fuoco] [http://krychan.ifrance.com/content/view/smaltimento-cartuccia.htm smaltimento cartuccia toner] [http://dejablu503.ifrance.com/description/lib/il-conte.htm il conte di montecristo. vol. 02] [http://joshuaw-wise.ifrance.com/img/styles/behringer-basso/ behringer basso] [http://call-shotgun.ifrance.com/view/new/il-cimitero/ il cimitero del sole] [http://cocopuff66.ifrance.com/text/directory/piano-songs/ piano songs] [http://nokros.ifrance.com/data/codi-tps/ codi tps] [http://nokros.ifrance.com/data/fast-walking/ fast walking] [http://call-shotgun.ifrance.com/view/new/costi-costruzione/ costi costruzione] [http://atrayah.ifrance.com/topic/gattino.htm gattino] [http://lightmyfire0214.ifrance.com/topic/il-buono/ il buono il brutto e il cattivo morricone] [http://horcrionebay.ifrance.com/resources/articles/appartamento-vacanza.htm appartamento vacanza bibione] [http://lightmyfire0214.ifrance.com/topic/jenny-gart/ jenny gart] [http://squoi-oop.ifrance.com/topic/valerio-massimo/ valerio massimo manfredi libri] [http://gabe95.ifrance.com/html/renault-/ renault 19 1.8 16v] [http://krychan.ifrance.com/content/view/adidas-boxe.htm adidas boxe] [http://mfirishka.ifrance.com/view/new/cynic.htm cynic] [http://lightmyfire0214.ifrance.com/topic/kit-tele/ kit tele system common-interface] [http://trumanburb.ifrance.com/view/new/moto-mv.htm moto mv augusta] [http://trumanburb.ifrance.com/view/new/paul-johnson.htm paul johnson beheaded] [http://flawedamythyst.ifrance.com/img/styles/lampada-proiettore.htm lampada proiettore sharp] [http://flawedamythyst.ifrance.com/img/styles/caerca-con.htm caerca con google] [http://alishca-st.ifrance.com/text/directory/w-w.htm w w w sexo] [http://sm4.ifrance.com/lib/cavalli-cinture/ cavalli cinture roberto] [http://alishca-st.ifrance.com/text/directory/prevendita-biglietti.htm prevendita biglietti festivalbar] [http://call-shotgun.ifrance.com/view/new/pranzo-misterioso/ pranzo misterioso] [http://horcrionebay.ifrance.com/resources/articles/cj-clarke.htm cj clarke] [http://alishca-st.ifrance.com/text/directory/testi-gigi.htm testi gigi d alessio] [http://gabe95.ifrance.com/html/www-eiffel/ www eiffel65 it] [http://krychan.ifrance.com/content/view/ragazzi-gay.htm ragazzi gay] [http://nokros.ifrance.com/data/mt-/ mt 68 alu] [http://flawedamythyst.ifrance.com/img/styles/b-z.htm b z] [http://flawedamythyst.ifrance.com/img/styles/done-sexi.htm done sexi] [http://mfirishka.ifrance.com/view/new/radio-sangean.htm radio sangean] [http://alishca-st.ifrance.com/text/directory/etilen.htm etilen-] [http://lekusya.ifrance.com/library/html/nie-chce/ nie chce tego hajsu] [http://cocopuff66.ifrance.com/text/directory/pisa-cinghiale/ pisa cinghiale] [http://mfirishka.ifrance.com/view/new/milano-new.htm milano new york] [http://lekusya.ifrance.com/library/html/guncon/ guncon 2] [http://gajar.ifrance.com/html/video-pciexpress.htm video pci-express] [http://smegmacheez.ifrance.com/content/view/wolkswagen-passat/ wolkswagen passat tdi] [http://nokros.ifrance.com/data/mare-matto/ mare matto] [http://nokros.ifrance.com/data/naturalmente/ naturalmente] {| align=right
+
{| align=right
 
|-
 
|-
 
|  
 
|  
Line 17: Line 17:
 
[[Image:PG31-USB-Connection.jpg|PG31 USB Connection]]
 
[[Image:PG31-USB-Connection.jpg|PG31 USB Connection]]
  
The USB connector has four pins : Vcc (*around* 5V), GND, D , D-. Tying these four connections to the CP2102 is easy enough.
+
The USB connector has four pins : Vcc (*around* 5V), GND, D+, D-. Tying these four connections to the CP2102 is easy enough.
  
 
[[Image:PG31-USB-Connection-Schematic.jpg]]
 
[[Image:PG31-USB-Connection-Schematic.jpg]]
Line 35: Line 35:
 
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!
 
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!
  
One thing to note w
+
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...
1000
 
hen 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...
 
  
 
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!
 
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!
Line 61: Line 59:
  
 
You can see the PCB layout is pretty straight forward. The 'solder jumpers' are a feature that SFE came up with to minimize our manufacturing time while allowing end users to populate the physical jumpers if they needed the ability to connect/disconnect a feature often and quickly. Most users just plug the PG31 onto their computer for quick evaluation. At some point, the CP2102 IC may need to be disconnected from the circuit so that an external micro or embedded system could be attached. If this is done back and forth often, the end user can clear the solder jumper with a swipe of the soldering iron, install a 2-pin header and a black plastic jumper. This now allows them to jumper/dejumper quickly and keeps us from having to solder the 2-pin headers into a board that may not need them.
 
You can see the PCB layout is pretty straight forward. The 'solder jumpers' are a feature that SFE came up with to minimize our manufacturing time while allowing end users to populate the physical jumpers if they needed the ability to connect/disconnect a feature often and quickly. Most users just plug the PG31 onto their computer for quick evaluation. At some point, the CP2102 IC may need to be disconnected from the circuit so that an external micro or embedded system could be attached. If this is done back and forth often, the end user can clear the solder jumper with a swipe of the soldering iron, install a 2-pin header and a black plastic jumper. This now allows them to jumper/dejumper quickly and keeps us from having to solder the 2-pin headers into a board that may not need them.
1000
 
 
  
 
----
 
----
Line 71: Line 67:
 
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.
 
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.
 
----
 
----
===Documents===
+
==Documents==
 
[[Media:PG31 USB Schematic.pdf|PG31 USB Schematic]]
 
[[Media:PG31 USB Schematic.pdf|PG31 USB Schematic]]
  
Line 83: Line 79:
 
FP Name: PG31
 
FP Name: PG31
  
<b>Supplier Info:</b><br>
+
<b>Supplier Info:</b>
 
Spark Fun Electronics part # : Eval-PG31-USB<br>
 
Spark Fun Electronics part # : Eval-PG31-USB<br>
 
Single Piece Price : $29.95
 
Single Piece Price : $29.95
  
<b>Related Items:</b><br>
+
<b>Related Items:</b>
 +
 
 +
* [[PG31 GPS RS232 Dev Board]]
  
 
[[Category:Projects]]
 
[[Category:Projects]]

Latest revision as of 11:55, 16 December 2008

PG31 USB Dev Board

Description:
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.

In this project we demonstrate how to:

  • Setup a USB to Serial link
  • Use the CP2102 for 3.3V
  • Use a SMD 12mm battery holder

USB Connection[edit]

The CP2102 USB IC is fairly easy to use once you've plugged it down a couple times.

PG31 USB Connection

The USB connector has four pins : Vcc (*around* 5V), GND, D+, D-. Tying these four connections to the CP2102 is easy enough.

PG31-USB-Connection-Schematic.jpg

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.

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.

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.

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!

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.

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.

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!

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...

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!


Battery Backup[edit]

12mm coin cell holder

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").

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.


PG31 Footprint[edit]

PG31-Footprint.jpg

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...


Final Layout[edit]

PG31-USB-Layout.jpg

You can see the PCB layout is pretty straight forward. The 'solder jumpers' are a feature that SFE came up with to minimize our manufacturing time while allowing end users to populate the physical jumpers if they needed the ability to connect/disconnect a feature often and quickly. Most users just plug the PG31 onto their computer for quick evaluation. At some point, the CP2102 IC may need to be disconnected from the circuit so that an external micro or embedded system could be attached. If this is done back and forth often, the end user can clear the solder jumper with a swipe of the soldering iron, install a 2-pin header and a black plastic jumper. This now allows them to jumper/dejumper quickly and keeps us from having to solder the 2-pin headers into a board that may not need them.


Things to Improve[edit]

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.

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.


Documents[edit]

PG31 USB Schematic

PG31-USB Protel File

PG31-USB Gerber Files

Footprints:
SFE Footprint Library

FP Name: PG31

Supplier Info: Spark Fun Electronics part # : Eval-PG31-USB
Single Piece Price : $29.95

Related Items: