I bought a Synthetos gShield (v5b) board few months ago,

Controllers g2core and TinyG
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I bought a Synthetos gShield (v5b) board few months ago, but still were using Arduino Uno + grbl. Finally some days ago I decided to give it a chance. I flashed brand new Arduino Due with latest ‘TinyG G2 for Due + gShield 087-edge’ firmware using USB Programming port and the FW update feature available on http://www.chilipeppr.com/tinyg. Choosing right board from the list downloads firmware automatically - great feature from @jlauer .

Every first time I connect the Due/gShield to my PC I see Bossa Program Port (which I would normally expect with no TinyG firmware present) and not two TinyG ports. Pressing RESET on Due (or gShield) solves the problem until next time I need to connect. I replicated this already on two different Due boards - same result.
I tried to set the boot flag to 1 with bossac, same as when boot flag is set to 0.

Is that normal Due behavior or am I doing something wrong? I am quite sure this is Due and not the gShield causing this, but maybe someone got similar issues. Keep searching…

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SPJS should connect to the Native USB port on the Due once initially programmed, I believe. (Not the programming port).

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Ways to erase the board and get into the loader (BOSSA):

Hold ERASE while hitting RESET.

Connect to the Due at 1200 baud, then disconnect.

Connect with a hardware programmer and reset the NVRAM bit to boot from “ROM” (aka the loader aka BOSSA).

Ways to get out of the loader:

Program the board & set the NVRAM to boot from RAM and reset the board. Occasionally it won’t boot into RAM after this until it has been fully power cycled, but this usually only happens after using the ERASE button.

Hopefully that helps.