avrdude: stk500v2_ReceiveMessage(): timeout-workaround

[tjm3d_auto]

Hello, again.
Please, feel free to view some other posts I made about this problem and some others. I found a way to bring this gt2560revB back to life. After searching and viewing a lot of posts from many different forums, including links from this one, I decided this morning to fix it or break it permanently. To review the problem, I tried an upload yesterday with some mods. The upload went normally but when the MeCreator2 was rebooted I got an LCD with two rows of blocks and no further uploads would work, getting the message that's posted in the subject of this post.

Three common things popped up in the discussions along with some suggestions on making the uploads complete properly. First was the 16Mhz crystal, second was the FTDI chip FT232RL and third was the bootloader. I couldn't do anything about the bootloader right now so I chose the other two items. There was also a few posts I found that starting an upload and pushing the reset button at just the right time would allow a connection. I could not get this to work.

Anyway, first to check was the oscillator. I removed the board from the MeCreator2 and plugged in just the USB cable from the computer. The computer always did recognize that a USB connection was there and always showed up in the COM list. I could always make a connection with Repetier and/or Easyprint but got no communication, otherwise. I checked a bunch of stuff, including fuse power and chip voltages. Put a scope on the oscillator and found it working. 16Mhz but it appears to be halved as I only got an 8Mhz frequency. It works. The FT232 was next. I noticed a couple of things on the board. (see the pic). When I plugged in the USB cable, the power LED lit, the timer LED (I called it this for no particularly good reason, but it needed identification) lit, then went off, then came back on flashing at a rate of several times per second. Also, when the USB cable was first inserted the TX/RX LEDs flashed a couple times then went out permanently for the session. I was hoping that this meant the FT232 chip was working. I noticed this: after looking up the data sheet for the FT232 (genuine FT232 chip) it appeared the pin layout referenced to the position locator dot wasn't right. This, combined with some forum threads I found about bootlegged/copied FT232 chips along with the associated discussion of improper timing and reset functions for these AND the sequence I was seeing with the LEDs, I tried something. Here's the sequence: plug in the USB, the power LED lights, the Timer LED lights then goes out, TX/RX LEDs flash several times then the Timer LED starts flashing and then the TX/RX LEDs go out permanently. It took a couple of tries to time this right but first I got the sketch ready to go for an upload, started the compile and upload then as the compile finished I plugged in the USB, got power, timer LED went on and off, the TX/RX LEDs flashed just as the sketch started uploading and the timing got caught just right to keep the timer LED OFF and the TX/RX LED still indicated that a successful upload was taking place. Booted to my modified Marlin successfully, no more LCD with two lines of blocks and all appears to be back to normal. I suspect, but I cannot verify, that the FT232 chip has a timing problem. I may try to replace it. Below is the shot of the GT2560revB board. The bottom line is that the upload needs to begin while the TX/RX LEDs are indicating a receptive mode. I hope this helps.

By the way, I found absolutely no documentation on this particular board other than what ohter users have posted here and elsewhere. This board is NOT in the list of products offered for sale or replacement by Geeetech and no schematics or user manuals are available for it. Don't know why and don't really care although it would be nice to be able to get a replacement board, if needed.

Have fun,
Tony

[William]

Thanks for your selfless sharing that conveniences many printer lovers.

[tjm3d_auto]

Thanks, William.

Can you get us some data and schematics for the revB board? That would help a lot.

Tony

[William]

Date and schematic would help you a lot ,but i am sorry those are not open.