Update RUMBA board bootloaders ATMega256 and At16u2 using an ArduinoMEGA... HOW?

Hi!

So here's the scenario:

A RUMBA board (mix of RAMPS + Arduino MEGA256 in a single board) which has the common USB noise/cut operation/connection drops.

The macos ElCapitan sees the device using lsusb reports the device as ATMega256:

$lsusb
Bus 020 Device 007: ID 2341:0010 2341 Arduino Mega 2560 Serial: 95334323917191


If I unplug the USB, the device does disappear from lsusb.


If I try to burn either of the bootloaders (MEGA256 or AT16u2) onto their chips using an ARDUINO MEGA256, all I get is a timeout... BUT if i click the arduino reset button while the timeouts happen, I get this:


-----------------------------------------

avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x000000
avrdude: Yikes! Invalid device signature.
avrdude: Expected signature for ATmega16U2 is 1E 94 89
avrdude: reading flash memory:

Reading | ################################################## | 100% 9.96s

avrdude: writing output file "RRD-RUMBA_ATmega16U2_USB2Serial.hex"

avrdude: safemode: Fuses OK (E:00, H:00, L:00)

avrdude done. Thank you.

-----------------------------------------

Also if I try to simply upload a sketch onto RUMBA, all I get is


avrdude: stk500v2_ReceiveMessage(): timeout


over and over.




So to sum up, I need:

1) burn the .hex bootloader onto the 16u2 chip
2) burn the other .hex bootloader onto the MEGA256
3) upload a sketch on the flashed RUMBA


but all I can get to is a board that is recognized by the system (plug/unplug) and times out.


Interestingly enough, everytime a timeout is reported by avrdude, the RX led on the RUMBA lights up (but no TX activity at all).



I've checked most of the Google links on "RUMBA" and 16u2, timeout, avrdude to no avial.

Needless to say, there's no way for RUMBA to enter in "DFU" mode as suggested by the RepRap wiki... So far I dont think anyone succeeded in such task.


Weirdly enough, I tried to follow this tutorial:

https://www.nova-labs.org/wiki/3d_pr...mba_bootloader

But aside from NOT working as expected, I notice the Arduino page suggests to use pin number 10 instead of pin 53 like in that link.



Thanks!