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Topic: Homemade PCB, no VUSB (Read 14461 times) previous topic - next topic

Homemade PCB, no VUSB

Hello. I've recently built a single-sided, through-hole version of the USB IR Toy v2, using the schematic posted on the wiki for it without the pin breakout area.

Now, i can program this device just fine through ICSP using the .hex files provided in the package, but the thing is VUSB never raises to 3,3v (floats arround 0,6v) with any of them, so the device never ennumerates. I can confirm the device works flawlessly otherwise (the bootloader alone responds correctly to shorting PGC/PGD after a reset, for example).

Right now my VUSB pin is connected to ground via a .47 uF cap, but i've tried several values without making any difference

¿Could it be possible that some configuration bits need to be set up manually? I've checked the design so many times i'm positive that it is correct. Is either that or a dud 18F2550 with a broken internal regulator, but i've never seen such a thing happen in the past. I've used a JDM-type programmer with both WinPic800 and piklab-prog, with identical results.

Thanks in advance!

PS: If anyone is interested in a single-sided PCB for the IR toy just let me know. Mine is 40x50mm using an USB-A connector and includes a USB pin header, VCC/GND/RX/TX header for serial communications and ICSP - had to dispense with the pin breakout area though.

Re: Homemade PCB, no VUSB

Reply #1
That sounds interesting.  Though I'm afraid I can't help much with the issues you're having, I'd like to see your project.  Do you have any photos you can post?

Re: Homemade PCB, no VUSB

Reply #2
[quote author="schazamp"]That sounds interesting.  Though I'm afraid I can't help much with the issues you're having, I'd like to see your project.  Do you have any photos you can post?[/quote]

Sure, no problem - i'll snap some pictures as soon as i get home today.

EDIT: Here you go - sorry about the lousy quality :) Notice that there's no QSE159 as i haven't been able to locate that part locally yet.

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Re: Homemade PCB, no VUSB

Reply #3
I finally broke down an got a new 18F2550, which worked perfectly from the beginning. This must be the first time i ran across a broken PIC...

Anyway, this is a great little device. It's now receiving IR for my HTPC system and works great. Thank you for your hard work guys!

Re: Homemade PCB, no VUSB

Reply #4
Awesome build, thanks for posting! I'll blog it up.

Do you plan to publish the PCB files? If it's open source I'll include it in the SVN and release packages.
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Re: Homemade PCB, no VUSB

Reply #5
[quote author="ian"]Awesome build, thanks for posting! I'll blog it up.

Do you plan to publish the PCB files? If it's open source I'll include it in the SVN and release packages.[/quote]

Sure, be my guest! :) I've designed the board using PCB and gSchem. If that's good for you i'll review the designs to clean them up in order to get them ready for publishing.

I also have a PCB design with the pin breakout area, which i didn't quite like because it's more crowded and leaves little copper to connect the "ground plane" areas on the board. It's the same design and schematic though so it should work just fine.

Re: Homemade PCB, no VUSB

Reply #6
Post it up, whatever the format, as long as you're ok with an open license. If it isn't based on our files (cc BY-SA), please specifically state the license you want so I can include a note with the files.
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Re: Homemade PCB, no VUSB

Reply #7
[quote author="ian"]Post it up, whatever the format, as long as you're ok with an open license. If it isn't based on our files (cc BY-SA), please specifically state the license you want so I can include a note with the files.[/quote]

Creative Commons is fine. Attached is a rar with PCB, schematics, netlist files and images for both the regular design and the one with the breakout area, in case someone finds it interesting.

EDIT: I've found out a typo in the schematics (the emitter resistor for the IR Leds' CCS was incorrectly labeled 6k8 instead or 6R8). The attached files are now corrected. Sorry!

Re: Homemade PCB, no VUSB

Reply #8
Thank you so much. I added it to a contribution folder here: http://code.google.com/p/dangerous-prot ... %2Fcontrib
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Re: Homemade PCB, no VUSB

Reply #9
If you PM me your address I'll send the 159 sensor.
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Re: Homemade PCB, no VUSB

Reply #11
[quote author="LisandroP"]I finally broke down an got a new 18F2550, which worked perfectly from the beginning. This must be the first time i ran across a broken PIC...

Anyway, this is a great little device. It's now receiving IR for my HTPC system and works great. Thank you for your hard work guys![/quote]

I've personally had 18F2550's with the very same issue, that ended up working after... heating!. Yeah, no VUSB, some heating, and off they go. Heating to 150ºC or so..., nothing close to or above reflow temperatures.That happened to me when I started making psgrooves for friends and that, and ordered a bunch of 2550's and like 3 of them had that issue.

I don't know what the hell happens to the 18FX550 series. I myself have broken like 5 4550's in TQFP44 in 3 different proyects in less than three months. With broken I mean that they were working, and suddenly they stopped. After checking the memory contents, the first 8 to 16 (or so) words were erased. It's magic. Some of them re-worked after reprogramming, some never started the oscillator again (literally). I first thought it was a USB ESD issue, but nopes. I also thought it could be something related to the "popcorn effect" while soldering, but nopes, I added some serious ESD protection. A """pre-baked""" chip also broke. I also had one that woudn't properly read the state of a pin, and guess what, worked after reheating. And poofed after a month.

Yeah, for me it also was the first time I saw a broken pic. In my early years I did all sorts of mistreat to those poor first PIC's that came to my hands, and all of them still work. I've only experienced that issues with FX550's, but never with any other PIC model, even with USB.

Re: Homemade PCB, no VUSB

Reply #12
[quote author="erdabyz"][quote author="LisandroP"]I don't know what the hell happens to the 18FX550 series. I myself have broken like 5 4550's in TQFP44 in 3 different proyects in less than three months. With broken I mean that they were working, and suddenly they stopped. After checking the memory contents, the first 8 to 16 (or so) words were erased. It's magic. Some of them re-worked after reprogramming, some never started the oscillator again (literally). I first thought it was a USB ESD issue, but nopes. I also thought it could be something related to the "popcorn effect" while soldering, but nopes, I added some serious ESD protection. A """pre-baked""" chip also broke. I also had one that woudn't properly read the state of a pin, and guess what, worked after reheating. And poofed after a month.

Yeah, for me it also was the first time I saw a broken pic. In my early years I did all sorts of mistreat to those poor first PIC's that came to my hands, and all of them still work. I've only experienced that issues with FX550's, but never with any other PIC model, even with USB.[/quote][/quote]

I keep hearing about all sort of strange issues with the 18F series. For example, i usually program my PICs with an old trusty JDM2 i built a long time ago. This device has programmed every single PIC i used without issues... except for the 18F2550/4550, where it requires a filter adaptor for the PGC/PGD lines (nothing more than 100Ohms and 27pF in series to ground). And this is regardless of the connector length. In fact, i hear people had issues using the PICKit2 with these devices.

In my experience, PICs are way more rugged than they should be. I've had PICs with overvoltage, reverse polarity, sinking several times the maximum rated current or incorrectly wired and they always seem to survive without a hitch. I've recently had a 3,3v receiving 13v on some GPIO pins! So, when something breaks with a PIC design the device itself its usually the last thing i check.

Thanks for the heating tip BTW. I'll try it tomorrow... i've seen stranger stuff happen :)

Re: Homemade PCB, no VUSB

Reply #13
Also remember to use a diode in series on the MCLR line of the JDM2 - it puts 13volts on MCLR and the 18FX550 can take max 12.6 or 12volts or something.
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Re: Homemade PCB, no VUSB

Reply #14
[quote author="ian"]Also remember to use a diode in series on the MCLR line of the JDM2 - it puts 13volts on MCLR and the 18FX550 can take max 12.6 or 12volts or something.[/quote]

12.5v max, IIRC. To be honest i never cared about it, as it seems that both the 18Fx series can be programmed at 13v and the 16Fx series can be programmed at 12v in my experience. Still, yes, it's out of spec.