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Topic: PIC USB Backpack (sorta!) Assembled (Read 8949 times) previous topic - next topic

PIC USB Backpack (sorta!) Assembled

Hi All,

I thought I'd start my own thread for the assembly of my PIC USB Backpack. I say 'sorta!' in the topic title because I don't plan to use this board with an LCD, but rather as the basis of a development platform to experiment with some USB code.

So far, my board is assembled, but it's not yet working. I loaded it with the bootloader and firmware for the PIC USB Backpack to test the board, but nothing happens when I plug it into my PC. I know what to expect because I also have an USB IR Toy that's working fine.

[attachment=0]

I checked the board carefully with a microscope, and did not see any shorts. I also checked the board for shorts with a continuity tester and did not find any. At this point, the assembly looks good!

I'm programming the board with a CCS USB PIC progammer, and everything seems to go OK during the firmware upload, yet it's not working. I did note that the voltage on pin 14 (Vusb) is 0, so it does not appear that the internal 3.3V reg. is being enabled. That explains why there is no USB activity, but not why the lack of enable. I suspect some minor difference in my programmer may be the problem, and the chip is not being programmed correctly?

I added an LED to the board today but ran out of time to write a small program to test if I can get that to work. Unfortunately, this effort may have to wait a few weeks as I'm traveling to Vietnam on Thursday for a couple of weeks. Sigh! So many projects, so little time!

John

Re: PIC USB Backpack (sorta!) Assembled

Reply #1 –
Quote
I did note that the voltage on pin 14 (Vusb) is 0, so it does not appear that the internal 3.3V reg. is being enabled. That explains why there is no USB activity, but not why the lack of enable. I suspect some minor difference in my programmer may be the problem, and the chip is not being programmed correctly?

It sounds like you found a solid starting point. The Vusb is either not activated or it is broken.

The internal regulator is enabled with a configuration bit, it cannot be accessed from code. That makes me guess (if it isn't broken) that the programmer is not covering the configuration bit range.

For programming: the best file to use is the -DUMP, it contains both the firmware and bootloader.
Got a question? Please ask in the forum for the fastest answers.

Re: PIC USB Backpack (sorta!) Assembled

Reply #2 –
Hi All,

Just a quick update to say it looks like a programming issue is causing the problem with my board. This morning I burned the chip again with the -DUMP version of the firmware, and then read the data right back to compare to the original file. For the most part they are the same, but there are a number of very subtle differences at a number of addresses. I don't have time now to track them all down, but this is undoubtedly the problem.

I did make a small test program (with the CCS compiler) that flashes the LED I connected to RC1, and that works fine. So, until I get back from my trip and can continue this project, I now have the worlds most sophisticated 'LED Flasher'!

Thanks,

John

Re: PIC USB Backpack (sorta!) Assembled

Reply #3 –
i have tried the firmware on a breadboard hand have run into a problem with the .inf win7 x64.

windows will not install the driver have not figured it out yet.

it enumerates but does not assign correct driver.

Re: PIC USB Backpack (sorta!) Assembled

Reply #4 –
It could be that I messed up the USB ID in either the firmware or the inf.
Got a question? Please ask in the forum for the fastest answers.

Re: PIC USB Backpack (sorta!) Assembled

Reply #5 –
i have not had the opportunity to check out the source, i am unfamiliar with the microchip usb stack.

as i am not very proficient with svn i may not have the most current firmware.

Re: PIC USB Backpack (sorta!) Assembled

Reply #6 –
Theres a new release on the blog right now, maybe that will help. You can check the windows device manager for the ID and open the .inf/.cat file and the ID is in plain text. I will check it out tomorrow too, as I have to update the package for manufacturing.
Got a question? Please ask in the forum for the fastest answers.

Re: PIC USB Backpack (sorta!) Assembled

Reply #7 –
i have checked the uid and vid do not match, :(

id build it myself if i can find the correct mchp usb files

Re: PIC USB Backpack (sorta!) Assembled

Reply #8 –
it seems that the ...firmwareusb_descriptors.c" file is not present.

i am not sure where this file is located?

Re: PIC USB Backpack (sorta!) Assembled

Reply #9 –
You have to get that file from the Microchip TCPIP stack serial port demo, we cannot redistribute it.

I programmed the DUMP firmware and used the inf in the package. Using the latest package version the USB ID in windows is 0X04D8 0XFA97, the same as the .inf file. There was an extra space between the values, maybe that was an issue. I also updated using the bootloader and it also had the correct VID. I attached an updated user package here, maybe that will help.
Got a question? Please ask in the forum for the fastest answers.

Re: PIC USB Backpack (sorta!) Assembled

Reply #10 –
i have figured it out problem with bread-boarding usb-> need to be more careful with the usb connections.
had to build circuit a 2nd time
need more than 2 different colors of wires.

Re: PIC USB Backpack (sorta!) Assembled

Reply #11 –
[attachment=0]

i got it working, unfortunatly the only lcd i had avalable was salvaged from an old fax machine and was 1/2 broken. the last 8 characters will not show up, time to order some new lcs

Re: PIC USB Backpack (sorta!) Assembled

Reply #12 –
is there any work being done getting the back light and contrast controls working?

Re: PIC USB Backpack (sorta!) Assembled

Reply #13 –
[quote author="sqkybeaver"]
i got it working, unfortunatly the only lcd i had avalable was salvaged from an old fax machine and was 1/2 broken. the last 8 characters will not show up, time to order some new lcs[/quote]

I had some trouble with a similar unit, try using it as 8x2 display, instead of 16x1.

Re: PIC USB Backpack (sorta!) Assembled

Reply #14 –
[quote author="fcobcn"][quote author="sqkybeaver"]
i got it working, unfortunatly the only lcd i had avalable was salvaged from an old fax machine and was 1/2 broken. the last 8 characters will not show up, time to order some new lcs[/quote]

I had some trouble with a similar unit, try using it as 8x2 display, instead of 16x1.[/quote]

i have since switched to an 16x2 display and it has been working well since.

i am interested if there have any developments in the firmware(jtr/honken usb stack) i'd like to tweak it but am not familiar with the microchip usb stack.

want to add rotary input + buttons