[Rumba + FGS-LCD-C] USB connection and flashing problem

Hi, I'm having some problems trying to run my RUMBA + FGS-LCD-C with my in progress build new printer (TAZ).

I wanted to check my first wirings (X motor, X endstop and FGS-LCD-C).

A picture :



The first problem I have is that the USB connection doesn't work. A detail in case it can be usefull, the TR/RX lights were off all the time.

I followed the instructions reported on the RepRap wiki (DFU mode...), without any success.

So I flashed the 16u2 chip with my USBtinyISP and the firmware given on RepRap wiki.

Since then I have the TX/RX orange lights on all the time, no blink, like on the picture.

No USB connection under Windows XP. I have something using Ubuntu.

So using Arduino IDE under Ubuntu, I tried to upload Marlin firmware.

It doesn't work reporting timeout issues.

I connected my USBtinyISP on ATMega2560. By this way it seems the firmware upload is working (I'm not an expert, I don't really know if it is effectively the case).

But, if now I have light in the LCD, nothing displayed, it doesn't work. And no connection with host.

So I tried to flash the ATMega2560 with my USBtinyISP.

I got a verification at the end :

Quote

avrdude: verification error, first mismatch at byte 0x3e000
0x0d != 0xff
avrdude: verification error; content mismatch

I searched the net and it is unclear if it is a real problem or not. Some are reporting their boards working after such flash with this message.

What I can report in my case is that it didn't change anything. I still can't upload firmware directly via USB, and what I think I've uploaded via USBtinyISP, behaves the same way (light in LCD but it deosn't work).

Any help, check, idea or orientations are welcome.

Regards

PS : I reported a ticket with my order reference.