A big advantage of the SAMD MCUs is that you have a UBS connection without an additional chip. But this can also be a disadvantage if you need an isolated USB connection. There is a chip that can isolate USB, but it costs almost $ 20. That is uneconomical. There is a 2nd cheapy option. Isolation is done with an USB chip (Ft or CHM). Then UART comes out via optocoupler and goes to the SAMD UART-TX/RX. Now my question: Can the bootloader also load programs via this UART? Usually you do this via SerialUSB and over the built in D+/D- pins.
Hi @rsardu
Yes it can. On an Arduino Zero it's possible to upload code over the Serial1 D0 and D1 pins.
I've successfully tested this, by manually setting the microcontroller into bootloader mode with a double tap of the reset button, then uploading. (I haven't tried to see if it's possible to also connect the reset pin to allow auto-reset though).
Thanks Martin. That already sounds good. I'll try when I have the USB chip and the opto coupler.
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