Looking at the different datasheets and documentation the USB connection can be switched between the Renesas and ESP32 processor (default) This can be done with the U2 and U6 analog switch. Looking at the schematics I am confused. The SJ1 should be connected to make the switch, but it seems that R…

[image] awneil: Is there a note somewhere else that R21, R53, R54 and R55 are "Do Not Fit"? there is 0 next to the resistors

Wondered about that also but I looked with the interactive viewer (bottom page of https://docs.arduino.cc/hardware/uno-r4-wifi ). It seems that they are populated just below U2 and U6. Also looking at my board I "think" I see them (but it is too small for my eyes to be 100% sure :smile: ) regards, …

[image] Juraj: there is 0 next to the resistors That just indicates that they are zero-ohm links. As @paulvha said, if zero-ohm links were fitted in those positions they would, indeed, render U2 & U6 useless, and connect the USB DP & DN directly to both the ESP and the Renesas!

https://docs.arduino.cc/tutorials/uno-r4-wifi/cheat-sheet#usb-bridge

Again, if those zero-ohm links are fitted, then that cannot work! [image] R21 & R53 short-circuit U2; R54 & R55 short-circuit U6. Correction: R21 & R54 short-circuit U2; R53 & R55 short-circuit U6. Maybe this makes it clearer: R21 & R54 short-circuit U2: [image] R53 & R55 short-circuit U…

Thanks. That would explain P408... The document states to use D40, it is just there is no D40 and there is NO offset 40 defined in variant.cpp. P408 is on offset 21 in the table. Next to that, I wonder what happens if you pull P408 low while JS1 is connected..... I expect you to destroy at least P4…

[image] paulvha: The document states to use D40 it is pin 21 arduino/ArduinoCore-renesas/blob/44e51bd952b0132a7affa7fd0fce835e51a58995/variants/UNOWIFIR4/variant.cpp#L49 { BSP_IO_PORT_04_PIN_10, P410 }, /* (12) D12 */ { BSP_IO_PORT_01_PIN_02, …

exactly... offset is 21 not even, D21as it does not exist. That is the easy part to fix in my mind with better documentation. The hardware is more concerning: Are these resistors bypassing U2 and U6 already? What if you set P408 LOW and have Js1 connected.. you then connect +5V through P408 to G…

[image] paulvha: Are these resistors bypassing U2 and U6 already? If they are as shown in that schematic, then they would. If they are as shown in that schematic, then both the ESP and the Renesas would be connected direct to the USB DP & DN. So either that schematic is wrong, or those res…

Just to show the locations. With a bit of luck and magnifier, (and much better eyes then mine) you might be able to spot R21 and R53 R21 [r21_location] R53 [R53_location] R54 [R54_location] R55 [R55_location]

USB connector switch

Official Hardware UNO Family UNO R4 WiFi

awneil August 21, 2023, 8:48am 21

Another example of "Do Not Fit" parts not identified on schematic?

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USB connector switch

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