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Topic: UART at Boot Up (Read 525 times) previous topic - next topic



I am using 2 arduinos in my setup. One  sends data over UART and the second one should write them to a SD card. Now I have the issue, that if the second one wont start, if the first one is sending data over the uart at boot time. Even my PC doesnt recognize the Device right then. So for me, it Looks like the second one changes in a sort of bootloader mode , if it gets data over the uart at boot time. The data are recieved via Serial1.

Does someone know a fix for this issue or can confirm my theory ?

Thanks for the help!


Schematics and sketches would be invaluable here if you could ?

MKR's have what amounts to two COM ports and yes you are correct in assuming one is BOOTLOADER mode.

You can test that with a single MKR by double tapping the reset button quickly which will put it into bootloader mode on a new COM port.

It sounds like you might need to wait for the regular COM port to assert itself on the host before starting transmission from the client.
There is a WHILE SERIAL command you can use but it sounds like you may need a little more than that.
Help on the topic here

It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

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