China Mega 2560

So then I am left with the 8U chip being 1. Defective, 2. Unprogrammed or 3. Issues with the connector/input circuitry to the 8U. I didn't check the clock for the 8U. I did overlook that. That leaves me with one question... Can the Mega be programmed If I 'cut' the end off of a PL2303 type USB to RS232 adapter or can I use an FTDI 232 as I have both the FTDI Chips as well as some PL23XX cable assemblies. This is of course to be done only if the 8U chip cannot be re-programmed. I haven't the tools to remove the 8U, Trying to do so w/o the solder re-work equipment would not be a great idea. What I really have half a mind to do and that is just to toss the damned thing and buy a real one next month. I hate to be obligated to others for things I can reason out. IMO

Doc

Well let's not throw it out yet. When you try to upload to the board in the usual way, what happens exactly? Can you go into "verbose upload" mode and post what you see?

Bear in mind you can program it, since the main chip works, either through the ICSP interface or through the serial interface (as it has a bootloader) if you got an FTDI cable.

What ought to work is to leave those wires connected, upload the ArduinoISP sketch to the other board, and then use the ArduinoISP method of uploading. That totally bypasses the 8U (or is it 16U) chip.

Also, does the 8U chip have its own ICSP header, like the new Unos do?

Did you try connecting it to a different PC?

No, I used the cable and port assignment that works for my Uno R3 and my computer doesn't recognize the Mega 2560, Period... When I first plugged it in my computer wanted to install a CP2102 USB Driver and when I tried to "re-install" the heretofore "Working" Driver from the Arduino IDE install package the message from the PC (X86 Win7) was that it was not the right driver... Plug the Uno in and it works just fine. So it is my belief that the USB chip (the 8U2) is either defective or there is a problem with it's programming. I just tried again just now to U/L a sketch to the Mega 2560 and the same message was presented," No Device Found on COM 15" (My USB serial port) and I then reset the board ID in the IDE to Uno and plugged in my R3 and uploaded a sketch successfully. Same Cable, same work area, I only moved the boards about 4 inches, not the cable. The Mega had the Blink sketch loaded out of the Box and failed to be recognized immediately when I plugged it in W/ - W/O the IDE running. Most difficult as my 'Old Beady Eyes' make even looking at that chip difficult and my shaky hands make measurement a difficult task as well, well just a little difficult... IMO

Doc

Does the 8U chip have its own ICSP header, like the new Unos do?

What do you see in your device manager? This is what I see:

And if I uninstall the device driver I see this:

What do you see? Screen shot please.

I don't know how to do a Screen Shot" ( never did it before ) however when I plug in my Uno R3 it reports correctly in the device manager as an Arduino Uno R3 under the Com port tab and when I plug in the Mega it reports an Arduino Mega 2560 with the little yellow ! symbol (Driver trouble symbol) But this is under the Other devices tab and not under the Com Port tab as it should and there is no com port associated with it. Yes there are ICSP pins too, for both uProc's... It Looks like a real Mega 2560, even to the useless reset switch (if one has a shield installed the switch is well protected and hidden)... I do hope this helps.

Doc

it reports an Arduino Mega 2560

It sounds like it is enumerating, which means it can't be that faulty.

Are there any special markings on the board which might suggest what it is, exactly (like, a web site)? Some boards come with their own device drivers. I think if you can get the device driver installed your problems will be over. I think I read somewhere it isn't exactly a "driver" but a .INF file that has to match the board's USB "signature".

No, unfortunately it only is marked Arduino.CC no other markings. It is a Clone that was marked to look almost EXACTLY like an Arduino 2560 except it is marked "Design in Italy" instead of "Made in Italy" I didn't pay for the board it was a gift form a guy that I trade work with. He said that he was asked to take the product down from Ebay and just "Gave" me one for my private use. What about "making" a cable for it I have the means to easily put a FTDI232R (ssop package) or I have several PL23XX (03?) USB to 5V RS232 adapters. Is there any sserious down side to doing the programming that way, except the 'reset' issue... Barring that, Where might I look for that .inf file???

Doc

You have a number of ways you can go now. I'm no USB installation expert. I believe there is a way of finding the USB "signature", that might help find the .inf file. What happens exactly when you install the one it wanted to install? Does the yellow "!" go away? I would let it do its stuff and then see what COM port it reports.

Other options:

  • Get (or make) an FTDI cable, and plug that into TxD, RxD, Gnd and +5V. Also connect up RTS to reset via a 0.1 uF capacitor.
  • Program via the ICSP header - you could configure your other board to have the ArduinoISP sketch on it
  • Reflash the U8 chip - that might make it look like a standard Mega2560 ... and it might not.
  • If you have a SD board handy you can use the "hex file uploader" sketch I wrote (link below) - note that the pins on the Uno side are different as it uses MOSI/MISO/SCK for the SD card
  • Find the .inf file and get the U8 chip on your Mega to work
  • I think there are posts about people who remove the chip from their Uno (or Duemilanove board) and just use that as an "go through" FTDI board

Hex file uploader:

If you are planning to reflash the U8 chip I would first use the same process you did to find the chip signature before, but this time plug into the ICSP header (for the U8 chip) instead. That might help confirm what firmware is on it. Check carefully you get the pins right.

Also before reflashing download the current contents of the chip, just in case.

Ya know, making the USB Adapter seems the best of all in that I can have some lights on it and I have a mega shield (by mistake long B4 the Mega) that has a footprint on it that the FTDI232 chip will fit... So... com port 0 on the mega? Finding the USB Device id would be something of a challenge as I think it might be more dependent on my computer... It hasn't acted the same... any two different times. I will go through the hardware installation, the way that windows wants... "Find New Hardware", can't hurt and it is one more thing checked out/off the list.
Down side to re-flashing the 8U... If I can't get windows to recognize the chip and the serial cable method is too.. well as they say... can't hurt it anymore than it is. The fact that it is partially recognized is a good argument for something, deciding what is I guess the Mark of the Man... Just had a weird thought, the board came with a regular usb cable but it is blue... I wonder
I also wonder as a noob what might be different or untouchable without a special programmer in the 8U2. Something just occurred to me??? how or where is the board id stored, in the 8U2 or is there some kind of interchange with the Big Chip for device id, Windows clearly knows what it is... at any rate I am going to save the link to that page and your others, gonna make a folder in Chrome just for useful links like that... much like I used to keep a good macro library for coding, good routines/functions can save a lot of work, some clever of necessity.

Thank You, Sir, Again for your Time, Your Insights and knowledge and most of all thank you for the Hope I have again in this thing.

Doc

Hm, I sort've remember seeing one of those on ebay ("China Mega" or similar) from a vendor who I bought some Nordic semiconductor breakout boards from (also from Shenzhen). IIRC they had some bare-PCB "china megas" for sale too that were cheap (well, cause they were just unpopulated PCBs :wink:

Something just occurred to me??? how or where is the board id stored, in the 8U2 or is there some kind of interchange with the Big Chip for device id, Windows clearly knows what it is

The chip signature you could obtain using the "board detector" sketch. However inside the flash somewhere would be the USB signature for the device it is pretending to be.

OH... I was hoping that there might have been more, like the 8u talking to the mega... oh well just finished dinner will keep You advised as I go. I didn't ask how to configure the IDE to use a serial cable, on my mega if the ID is in the usb interface??? Go Fish? probably as good as any due to the education involved, methinks.

Doc

More in the Ongoing Saga of "Why Not To Buy a Clone" or "China Mega 2560"
and this was a gift... too.
Some further investigation leads me to ask where is the unique device ID stored on the Mega Board. MY Uno R.3 shows up in the Win7 (X86) Device Manager in the Port (COM and LPT)
Tab as UNO R3 (COMXX).
When I plug in the Mega Clone it Always reports under the Other Devices Tab as Arduino Mega 2560 with that yellow triangular symbol that has an exclamation point in it, occasionally the Mega will also enumerate as an Unknown USB Device under the Universal Serial Bus controllers tab again with the yellow symbol.... Considering the past issues with the board, I am nearly ready to turn it into Wall Art and buy a real one next.
Is it easily possible to re-flash the 8U2 on my board with the correct data W/O "Bricking" the processor and where could I find a real simple method and the files to do it with?.
I do have every thing as far as jumpers power supplies, Etc, a Real Uno R3 and most anything except a real Atmel Programmer, That is in the mail from China and not due for a week or so.

(Added Note) Has Anyone a suggestion as to the best USB to TTL Device to use. I have several different ones based on the PL2303 driver chip and I have a couple of the FTDI232R devices that I can assemble on a shield to plug into the Mega (Hate doing that as they're 28 Pin SSOP devices) but it is do-able. IMO

Doc

Have you tried uninstalling the device driver, unplugging it, and re-installing and accepting the driver it wants to install?

Failing that working, you could use the sketch here:

Note the wiring carefully. You will need SD card board.

You could read (save to SD card) the existing contents of the 8U chip, just in case.

Then you could reflash it with the 8U firmware (I don't think I have one but it should be on the web site here somewhere). That may or may not work. Possibly they used different pins on the 8U to stop you doing this. Or possibly the only reason they didn't put the "official" firmware on it was for copyright reasons.

My Mega doesn't have the ISCP pins (the header is just solder pads) so I can't easily read it.

Yes, Nick I did I went in and un-installed all the USB Driver instances I could find... So as to "level" the playing field and in the consideration that I might (and may still) have or had a driver conflict or that the device (Mega) was being rejected? as a defective device. I had further reason for this, in that hopefully my Mega might be recognized as a New Device.
No such luck, unfortunately.
I am sort of the mind that the code in the 8U2 is not returning the correct driver device information to windows and thus my board (Mega) isn't recognized properly.
Re-Flashing the Mega 8U2 seems the best way to go but I am open to any thing that works preferably with the least effort on my part.

Doc

What is the Hardware ID for the Mega that shows up under Other Devices?

Open Device Manager
Right Click the Mega device
Select Properties
Select Details tab
Choose Hardware Ids from the Property drop-down
Send us the Hardware Ids that show in the Value section.

Here they are: < USB\VID_2341&PID_0010&REV_0001 >
and the next one < USB\VID_2341&PID_0010 >
This device is found under the Tap Other devices Tab
I attempted to un-install/re-install the CP2102 and PL2303 drivers, My Uno would not Id until I re-installed the PL2303 drivers. Re installing the CP210X uart bridge package had no effect
I mis identified my machine earlier it is an Athlon 64, 32 bit machine with Win7 SP1 installed.

Doc

That Hardware ID indicates it is a Mega 2560 Rev1 or Rev2.
You should be able to install the driver for this device by pointing to the arduino\drivers folder.

Right click the device in Device Manager
Select Update Driver Software
Select Browse my computer for software
Click Browse button
Select the drivers folder under the location of your Arduino software installation
Click OK
Click Next