EEVblog #357 - USB Supply Power-up Testing - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: September 21, 2012, 07:38:33 am
content: Dave.

author: JoannaK
author_rank: Frequent Contributor
timestamp: September 21, 2012, 08:00:17 am
content: Yep... I know the feeling, component with 3 legs, definitely too many to get right each time..As an quick quiz I'd like to ask how many ways simple normal led can be put at the similat sot23 3 legged package..

author: andyg
author_rank: Regular Contributor
timestamp: September 21, 2012, 08:06:51 am
content: Ah, i know why there is no stock of the FTDI X series chips, as I got caught out myself too in a design.FTDI found a silicon bug which caused the chip to lock up unexpectedly (there is workaround by using a keep-awake pin) and pulled all the devices off the shelf. I bought a heap from Digikey and got an email, and they offered to return all the parts at their cost and to they were to send me replacements also at their cost.The details are here:http://www.ftdichip.com/Support/Documents/TechnicalNotes/TN_139_FT230X%20Errata%20Technical%20Note.pdf

author: EEVblog
author_rank: Unknown
timestamp: September 21, 2012, 08:12:51 am
content: Quote from: andyg on September 21, 2012, 08:06:51 amAh, that explains it!Thanks.Dave.

author: samgab
author_rank: Frequent Contributor
timestamp: September 21, 2012, 09:20:31 am
content: Quote from: EEVblog on September 21, 2012, 08:12:51 amAhh, well that was just bad luck, picking that particular chip. I was wondering if your mentioning of that chip had inspired keen young EEV hobbyists to go out there and buy up all the available stock!!

author: klinkerstein
author_rank: Newbie
timestamp: September 21, 2012, 09:26:33 am
content: Dave, you can easily omit the schottky diode coming from the battery around Q1. Seehttp://ww1.microchip.com/downloads/en/DeviceDoc/51746a.pdfPage 5

author: Mercator
author_rank: Contributor
timestamp: September 21, 2012, 10:42:54 am
content: How about the MCP2200 from Microchip? When I did the research for my own project, it was a lot cheaper than the FTDI ones. Or do you need some special feature, only the FTDI ones have?

author: Skippy
author_rank: Contributor
timestamp: September 21, 2012, 11:47:20 am
content: Are there any more documents/ circuit diagrams/ other stuff as well as the videos? I think I've watched all of the videos, and I'm still a bit unclear as to what it does and how it works. Last time you were looking at a DC/DC converter, suddenly now an entire constructed PCB appears!

author: EEVblog
author_rank: Unknown
timestamp: September 21, 2012, 12:06:21 pm
content: Quote from: Skippy on September 21, 2012, 11:47:20 amYeah, magic!The plan was to do the schematic videos etc first, but the board got rushed through so I decided to shoot it and mix it up a bit.Dave.

author: Thor-Arne
author_rank: Unknown
timestamp: September 21, 2012, 12:50:50 pm
content: Hm, where's the tutorial mentioned at 6:20 in the video?

author: free_electron
author_rank: Super Contributor
timestamp: September 21, 2012, 01:11:19 pm
content: Quote from: andyg on September 21, 2012, 08:06:51 amAh. That explains why i saw occasional lock ups with those.. I scored a few of their demo boards at ces last year. When playing with them it would go wonky sometimes. I blamed it on the breadboard at that time...

author: nitro2k01
author_rank: Frequent Contributor
timestamp: September 21, 2012, 02:46:20 pm
content: Quote from: Thor-Arne on September 21, 2012, 12:50:50 pmHe has added an annotation link now, but here it is for good measure:

author: Thor-Arne
author_rank: Unknown
timestamp: September 21, 2012, 03:01:29 pm
content: Quote from: nitro2k01 on September 21, 2012, 02:46:20 pmGreat, thanks.

author: OndraSter
author_rank: Contributor
timestamp: September 21, 2012, 03:52:25 pm
content: Don't worry, I have used LM2936's footprint instead of regular 1117-3v3 LDO. I had to bodge it up on the first revision of the board as well.Also, why are you using FTDI? There are AVRs and PICs with USB built-in.I bet that xmega32a4u would be cheaper than the mega you have there (or at least it looked like Atmel's logo on it) + FTDI. Not Arduino compatible though.

author: Mr Smiley
author_rank: Frequent Contributor
timestamp: September 21, 2012, 04:30:38 pm
content: I'm confusedWasn't the original idea;Isolated from USB supply.NO USB communication because it couldn't be isolated, and would considerable up the cost if it was.Fits into a small box with switches and display on the top.No battery backup.As simple but efficient as it can be.Lots and Lots of No's to other posters suggestions of control from the pc/laptop.Now we have buttons on the side, USB interface chip, battery backup, menu options and a soft on/off switch.Or has it been sooooooooooooooo long since Dave started this that I've missed something major.Mr Smiley

author: firewalker
author_rank: Super Contributor
timestamp: September 21, 2012, 04:37:39 pm
content: I think this is a merge of the two power supplies.Alexander.

author: DarkPrince
author_rank: Regular Contributor
timestamp: September 21, 2012, 06:41:19 pm
content: Unfortunate that it had to be rushed but at the same time it is really nice to see an update about the project. Woke up this morning seeing that you had a new video, and pertaining to the power supply projects; awesome!Now, I like this design. Low power supply but with alternate battery source. Good idea. Anything high powered, in my case, i'd just use an outlet anyway. Makes sense. Hope there will be another update sooner than later.Thanks Dave!Craig.

author: dolabra
author_rank: Contributor
timestamp: September 22, 2012, 01:27:16 am
content: Quote from: OndraSter on September 21, 2012, 03:52:25 pmBecause to sell it he would have to get a vendor id, or beg Microchip/Atmega to use thiers. Its a lot easier to use FTDI

author: dolabra
author_rank: Contributor
timestamp: September 22, 2012, 01:32:00 am
content: Am I wrong that most if not all sot-23 transistors have the same pinout?

author: EEVblog
author_rank: Unknown
timestamp: September 22, 2012, 03:40:11 am
content: Quote from: OndraSter on September 21, 2012, 03:52:25 pmThere needs to be electrical isolation. Doing so with USB is generally not cheap.Dave.

author: gxti
author_rank: Frequent Contributor
timestamp: September 22, 2012, 03:48:44 am
content: Last I checked MCP2200 is a bit cheaper than any FTDI part, although you do have to add a crystal.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: September 22, 2012, 06:35:43 am
content: Dave, what's in it to use that new shiny XS series? Surely a good ol' FT232 would do the job fine for this project?

author: EEVblog
author_rank: Unknown
timestamp: September 22, 2012, 08:58:18 am
content: Quote from: nitro2k01 on September 22, 2012, 06:35:43 amIIRC:a) It was the cheapest solutionb) It was the smallest solution. No need for external xtal and EEPROM.I knew it was new-ish, but didn't know how new, and I swear there were many thousands in stock at Digikey at the time. So seemed pretty safe.Dave.

author: David_AVD
author_rank: Super Contributor
timestamp: September 22, 2012, 09:04:28 am
content: The FT232RL is almost zero external parts count and a reasonably small package.

author: dda
author_rank: Contributor
timestamp: September 22, 2012, 09:14:39 am
content: Quote from: EEVblog on September 22, 2012, 08:58:18 amTrap For Young Players.Are you picking an alternative or do you expect to get your hands on some soon?

author: EEVblog
author_rank: Unknown
timestamp: September 22, 2012, 09:44:51 am
content: Quote from: David_AVD on September 22, 2012, 09:04:28 am$2.65 in 2000qty from Digikey.FT232XS is only $1.58Also 16pin SSOP vs 28pin SSOPMaybe cheaper on the gray market of course, but dunno.Like I said, it was cheaper and smaller, so I went with the 230XS.Dave.

author: klinkerstein
author_rank: Newbie
timestamp: September 22, 2012, 10:11:16 am
content: Quote from: EEVblog on September 22, 2012, 09:44:51 amOn the other hand, the FT232RL is almost industry standard ;-)

author: EEVblog
author_rank: Unknown
timestamp: September 22, 2012, 10:47:18 am
content: Quote from: klinkerstein on September 22, 2012, 10:11:16 amYeah, it seemed like a good idea at the timeDave.

author: David_AVD
author_rank: Super Contributor
timestamp: September 22, 2012, 10:49:18 am
content: Quote from: EEVblog on September 22, 2012, 09:44:51 amI'd pay $1 more just to use a more universal product. I do understand the tough choices when it comes down to choosing parts though.

author: EEVblog
author_rank: Unknown
timestamp: September 22, 2012, 10:54:16 am
content: Quote from: David_AVD on September 22, 2012, 10:49:18 amThat $1 more would make it the most expensive device on the board, and a larger increase on the retail price in which the BOM cost was creeping away beyond what I wanted.And there is the extra size too which played into it.Dave.

author: David_AVD
author_rank: Super Contributor
timestamp: September 22, 2012, 10:56:26 am
content: Quote from: EEVblog on September 22, 2012, 10:54:16 amAh, ya penny pinching bugger. lmao!

author: pachuma
author_rank: Contributor
timestamp: September 22, 2012, 11:09:31 am
content: So, why don't you get rid of the FTDI USB to UART converter altogether and knock off a few dollars worth of useless logic?Simply change the AVR to a micro-controller with a native USB interface either from Microchip or Atmel. Its something I've used on endless projects and helps to reduce the cost substantially.As we say over here: "if you want to get rid of rabies, simply kill the dog", i.e. solve the problem by removing it.

author: David_AVD
author_rank: Super Contributor
timestamp: September 22, 2012, 11:11:31 am
content: The one great thing about using the FTDI devices is the driver support. That's something that never seems to be as easy with USB enabled micros.

author: EEVblog
author_rank: Unknown
timestamp: September 22, 2012, 12:25:36 pm
content: Quote from: pachuma on September 22, 2012, 11:09:31 amIt needs to be isolated!Dave.

author: firewalker
author_rank: Super Contributor
timestamp: September 22, 2012, 12:36:31 pm
content: What about Prolific chips (PL2303)? I believe the cost less.Alexander.

author: dolabra
author_rank: Contributor
timestamp: September 22, 2012, 12:46:33 pm
content: Quote from: pachuma on September 22, 2012, 11:09:31 amDo you sell these projects? How do you handle USB Vendor and device ID?

author: OndraSter
author_rank: Contributor
timestamp: September 22, 2012, 01:01:01 pm
content: Quote from: EEVblog on September 22, 2012, 03:40:11 amI see. You are optically isolating the UART interface. Neat!(I couldn't find the "new" rev schematics on the web? Or is it the revC?)

author: pachuma
author_rank: Contributor
timestamp: September 22, 2012, 01:02:31 pm
content: If you use Atmel´s chips you can use their VID/PID for your device.You will not be able to splodge the USB compliant logo, but heck, it very much depends what you what to do with it.http://support.atmel.com/bin/customer.exe?=&action=viewKbEntry&id=220Ofcourse, there are several alternatives.

author: firewalker
author_rank: Super Contributor
timestamp: September 22, 2012, 01:03:50 pm
content: Quote from: dolabra on September 22, 2012, 12:46:33 pmThere is a way to use Atmel's, Microchip's PID:VID if I remember correctly?Using Arduino's USB<->UART code and PID:VID for a consumer product is legal?Alexander.

author: pachuma
author_rank: Contributor
timestamp: September 22, 2012, 01:19:53 pm
content: Quote from: EEVblog on September 22, 2012, 12:25:36 pmOK, IC.I was not aware that you had that requirement on spec, I need to go through the whole threadThen you have little choice. Unless when working off the battery it will be but not while in charge or configuration.BTW, have you considered to add a SCPI parser to control the gadget?

author: gxti
author_rank: Frequent Contributor
timestamp: September 22, 2012, 02:32:12 pm
content: Quote from: David_AVD on September 22, 2012, 11:11:31 amThe unfortunate thing about FTDI chips is that they need drivers at all. "Class-compliant" implementations, including MCP2200 but also probably all vendor-supplied USB UART examples, don't need a driver. Unfortunately due to the way windows does USB you still need a .inf file to bind the VID/PID to windows' class driver but on linux/mac it's plug-and-play.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: September 22, 2012, 04:07:21 pm
content: QuoteI got my "own" PID from Microchip in 1 or 2 days after requesting. As far as i remember a maximum of 10k units can be sold with this. Of course you also have to use a microchip product with this PID:VID combo.

author: Baliszoft
author_rank: Frequent Contributor
timestamp: September 22, 2012, 04:11:15 pm
content: Quote from: David_AVD on September 22, 2012, 11:11:31 amRight. Even the firmware is a PITA, not mentioning the pc drivers. LibUsb is a good (and free) alternative, however. Works well.

author: Rutger
author_rank: Regular Contributor
timestamp: September 22, 2012, 04:22:19 pm
content: I don't understand why Dave does use a bigger battery power supply for the main power with more power options, get ride of the isolation and only allow the USB for charging the battery. Add an option for an externally isolated power supply and you have successfully merged both power supplies into 1 small one.Oh and while were are at it, get ride of most buttons and display and only allow the interface via Bluetooth with an app for iphones & android.

author: Bored@Work
author_rank: Super Contributor
timestamp: September 22, 2012, 05:16:28 pm
content: Quote from: Rutger on September 22, 2012, 04:22:19 pmThat is just wank. You have never worked on a bench, doing some real work, did you? Then you would know you need knobs, real knobs, not that stupid fondling junk to wank about.

author: dolabra
author_rank: Contributor
timestamp: September 22, 2012, 05:59:19 pm
content: Quote from: firewalker on September 22, 2012, 01:03:50 pmI do not believe that it is.HW vendors like microchip and atmel have some special deal with the USB forum, everyone else has a non-transferable license to use the IDs

author: dolabra
author_rank: Contributor
timestamp: September 22, 2012, 06:13:44 pm
content: Quote from: pachuma on September 22, 2012, 01:02:31 pmfrom the link: "Customer must integrate the Atmel USB Flash Microcontroller Software and the USB descriptors with no changes"The way I read this is that you can use their example code unmodified. Which seem useless unless you just want a CDC class device to attach to something else.

author: T4P
author_rank: Super Contributor
timestamp: September 22, 2012, 07:52:54 pm
content: Quote from: firewalker on September 22, 2012, 12:36:31 pmI can't see a way to get them in one-off quantities (well, unless you bought a OHL rs232 adaptor and hack out the chip) for prototypingQuote from: Bored@Work on September 22, 2012, 05:16:28 pmIndeed. I hate wirelessly controlled devicesQuote from: Rutger on September 22, 2012, 04:22:19 pmYeah, really? He wanted a ISOLATED power supply that is totally isolated from the USB because of the noise that USB can coexist on the ground cableSo what if your battery is dead? Get a new battery? Don't want to! I don't want to have to wait for the battery to arrive from somewhere just because it's not easy to find locally at least cheap

author: Baliszoft
author_rank: Frequent Contributor
timestamp: September 22, 2012, 08:23:57 pm
content: http://ww1.microchip.com/downloads/en/DeviceDoc/APPLICATION%20FOR%20SUBLICENSE%20TO%20USB%20VID%20v3%20UPDATED.pdfQuote from: APPLICATION FOR SUBLICENSE TOMICROCHIP UNIVERSAL SERIAL BUS VENDOR IDIf Atmel does not allow to do this, that is a big FAIL *oaaaaaa*

author: pachuma
author_rank: Contributor
timestamp: September 22, 2012, 08:46:42 pm
content: Quote from: Bored@Work on September 22, 2012, 05:16:28 pm+1

author: firewalker
author_rank: Super Contributor
timestamp: September 22, 2012, 09:19:17 pm
content: About VIPD:PID. It seems there is a way to buy a combination for 10 USD.http://fourwalledcubicle.com/blog/2010/03/obtaining-a-vid-and-pid/(also read through the comments)Alexander.

author: opablo
author_rank: Regular Contributor
timestamp: September 23, 2012, 01:34:29 am
content: This power supply style is such a great idea… I’m really happy that you ended up with an lcd for the display after exploring all the other possibilities. Maybe the other were cheaper but lcd is the best way to go… Do you have any idea abouthow much are you going to price it ?Because I’m already interested in buying you one.Do you ship internationally ?(Argentina) I can even buy a pre-sale if that helps you fund the design efforts.

author: JoannaK
author_rank: Frequent Contributor
timestamp: September 23, 2012, 03:46:24 am
content: Quote from: andyg on September 21, 2012, 08:06:51 amHave to say that FTDI is a strange company, pulling product back entirely for just a small issue like that. I have seen a lot worse bugs on chips that been kept on selling trough distiributors.

author: T4P
author_rank: Super Contributor
timestamp: September 23, 2012, 08:03:48 am
content: That show they have pride in their parts - unlike Microchip whom chips come with a myriad of silicon bugs

author: Rutger
author_rank: Regular Contributor
timestamp: September 23, 2012, 08:27:48 pm
content: Quote from: Bored@Work on September 22, 2012, 05:16:28 pmJust because you think a UI is too hard too write? All you need is a on/off button. You set the voltage / current via the app, how much more tweaking do you need? Touch screen phones and apps are called progress, I bet you are still using a 'non' smart phone. Why re-invent the wheel for every unit, your phone has all the display you will every need, and it can log any data send by your equipment. This is not wank stuff, it is called progress.

author: Rerouter
author_rank: Super Contributor
timestamp: September 23, 2012, 08:55:16 pm
content: i hold nothing against there being the capability of phone control via bluetooth, but he is dead right in that a power supply should be usable on its own 2 feet in this case, your product starts to look like crap when you cannot use test gear when your phone is dead or missing, or is simply not compatible with the software

author: tom66
author_rank: Super Contributor
timestamp: September 23, 2012, 09:03:33 pm
content: Quote from: opablo on September 23, 2012, 01:34:29 amI hope this is a joke. I would hate to use a power supply over bluetooth or some unreliable wireless connection. Oops, bluetooth lost - now my dev board fries as it gets 10V instead of 3.3V and I can't turn it off because there's no on/off switch, voltage dial or otherwise. Or, oops, bluetooth lost, how much current did it just draw then, oh, you'll never know.

author: gxti
author_rank: Frequent Contributor
timestamp: September 23, 2012, 09:13:23 pm
content: Dangit, my troll meter is broken again. I was sure the first post was satire but now I'm just confused.

author: T4P
author_rank: Super Contributor
timestamp: September 23, 2012, 10:17:14 pm
content: Quote from: Rutger on September 23, 2012, 08:27:48 pmThat's not progress, that's going backwards.

author: opablo
author_rank: Regular Contributor
timestamp: September 24, 2012, 01:16:30 am
content: Quote from: tom66 on September 23, 2012, 09:03:33 pmI think I talked at the wrong time(in the middle of the bluetooth control discussion)I was talking to Dave in a general way and not about that bluetooth-control discussion.About that; I'm in favor of considering such a nice feature as that: a nice -extra- feature.My ideal interface would be an lcd able to show ongoing V and I at the same time and 2 buttons for "set v" and "set I" and a digital encoder knob.When I talked to Dave about "exploring other possibilities" I was talking about the binary encoded leds that he talked about once.This note is just clarification... sorry about it being this long.

author: lafontas
author_rank: Newbie
timestamp: September 24, 2012, 06:29:31 pm
content: Hey Dave, just joined the forums. You gave this product the review it deserved. I've been getting real enjoyment out of electronics since the 1960's when I put together some wire, tinfoil, batteries and a mechanical bell to make my first burglar alarmWhat frustrates me is that while arduinos, raspberries, et all have really made electronics accessible and affordable for total amateurs like me, decent bench scopes and such are still too costly.Hopefully we will see decent and affordable pocket oscilloscopes along with other tools in the near future.I enjoy your work, cheers.

author: EricBNYC
author_rank: Contributor
timestamp: September 25, 2012, 07:40:20 pm
content: Quote from: EEVblog on September 21, 2012, 07:38:33 amTWO Fluke 87v meters Dave? That's just showing off . . .

author: nitro2k01
author_rank: Frequent Contributor
timestamp: September 26, 2012, 03:14:51 am
content: Quote from: EricBNYC on September 25, 2012, 07:40:20 pmNah, just wait until he brings out four of them. Two for the input and two for the output.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 26, 2012, 03:29:07 am
content: I would recommend against the infamous PL2303, at least some of them have strange bugs. (At work, I have seen several devices that don't work with a PL2303 adapter. One actually managed to brick a thermal controller unit somehow. But FTDI adapters just work!)As for the USB IDs (if not using a FTDI), what's wrong with just making one up? Is it even possible to claim copyright on just 4 bytes of data?

author: gxti
author_rank: Frequent Contributor
timestamp: September 26, 2012, 03:51:06 am
content: If you don't play by the USB-IF's rules then they won't let you use their trademarks -- in particular the USB logo -- to advertise your product or its capabilities. There may also be patents (especially for USB 3) that are licensed on the condition that you pay all the appropriate fees. This includes not only the fee to acquire a vendor ID, but also per-unit fees that are usually baked into the price of the transceiver chips you buy. Certainly nobody is going to stop you from using arbitrary IDs for your own amusement, but once you start selling it to others you're at risk of legal action.

author: EEVblog
author_rank: Unknown
timestamp: September 26, 2012, 03:55:31 am
content: Quote from: nitro2k01 on September 26, 2012, 03:14:51 amI only have two!Dave.

author: Monkeh
author_rank: Super Contributor
timestamp: September 26, 2012, 06:31:38 pm
content: Quote from: NiHaoMike on September 26, 2012, 03:29:07 amPL2303s are cheap, and that's about all they have going for them. There are a lot of knockoffs, too.FTDI stuff is pricy, but it works well and is very flexible.