I am new to this forum and hopefully someone can help me out. The hardware was working fine but I created a short somewhere and one component was giving a burning smell. The component seems to do something with the USB communication to the computer. The computer is not recognizing the hardware. It is still powering up and the latest programm is also working fine.
I do have an FTDI programmer ans was wondering if I can use this to programm the Arduino Uno. I have tried to connect it with Tx to Rx and Rx to Tx, gnd to gnd and vcc to 5 v, but doesn't seems to communicate. The drivers are fine. i do see a working com port in the device settings.
I have searched on this forum and on google but can't find a working solution. Please help.
Thank you,
Jobertus
Take a look at the datasheet for the board available through Documentation.
The components close to the USB connector look like U2 and U6 in the schematic, multiplexers.
Other than that, I can't help you much.
Do you know what you were doing at the time?
It's very easy with these boards to get a short.
Even if you could replace the chips, the damage could have rippled out to stress other components.
Yes, it only concerns the U6. The U2 seems to be fine. Yes, it was a loose 5 volt cable from the relay circuit board that was touching the Arduino somewhere, causing a smell.
If I switch on the board it seems to be working fine but I am not able to write a new programm to it.
I think it is a TPS561243 regulator. If you have the skill set you can replace and try it. But first look at the correct schematic for that board to be sure.
That is why you never work with a electronic device with the power on. The parts fry in nanoseconds.
You might have done more damage than the obvious.
The new boards are tightly packed and the tracks and pads very fragile.
If it is one of the two chips, they don't look as though there are many pins involved.
You can lift the chip. I use a very fine scalpel blade and work round gently releasing pins.
You run the risk of lifting pads as well.
You could go to a lot of trouble and get nowhere.
It's a lesson learned and you aren't the first.
As per @tigger , according to the datasheet, the U2 and U6 are NLASB3157DFT2G Multiplexers. They handle USB switching between the ESP and the RA4M1 as both chips have native USB functionality.
If either U2 or U6 is toasted then USB communications is not going to be possible. U6 connects to USB pins on both the RA4M1 and the ESP32. In addition to the multiplexer, either processor chip could be damaged. Since ESP32 is a 3.3V chip, it is that much more vulnerable.
Assuming that the RA4M1 has not been damaged (the latest program still running sounds lie a good indicator of that), using an FTDI board might be possible but the R4 does not have automatic reset like earlier boards. You need to set the FTDI adapter to 3.3V. Connect Tx to 0, Rx to 1 and GND to GND. Hold down RESET when powering up the R4 to place it in bootloader mode. Then try uploading a sketch. Another option might be to try programming using a suitable programmer or another Arduino as an ICSP programmer, via the ICSP header.
Replacing the chip is no option for me as its microscopic small and I don't have spares as well. Besides that it is badly toasted and a big chance I will damage the tracks when removing it. I will try it with the FTDI connected like BitSeeker is proposing. If it is not working I will order a new one to see if I do the job with this ICSP header
It is true that the header you are referring to is an ICSP header on the classic boards. However, that is not the case for the UNO R4 WiFi. On this board, the header only provides standardized access to the SPI bus, and does not provide a low level programming interface.
The Renesas RA4M1 microcontroller's equivalent of the ISP interface of the AVR chips is SWD. The SWD pins are only exposed via these two test points on the PCB:
The ISP programmers we use to program the AVR chips can't be used with the SWD interface. It is possible to create a CMSIS-DAP compliant programmer/debug probe using an Arduino board. My recommendation for this would be:
(which can be used to turn a Raspberry Pi Pico board into a debug probe/programmer)
I have also done so in the past with other boards using the "Adafruit DAP library" library, but I haven't tried it with the UNO R4 WiFi as a target.
You can also purchase dedicated debug probes. I provide some information on that subject here:
That is about the UNO R4 Minima board, but it is equally applicable to the UNO R4 WiFi in the specific context where you don't have access to using the board's built-in "bridge" module as a debug probe.
Thank you. Interesting point to note. There is no sense in the OP trying that approach then. Also, with the SWD access being presented via test pads, this probably explains why there seems to be no mention of it on the pinout diagram.
Yeah, the expectation is that the on-board "bridge" module will be sufficient for the user's debugging and programming needs (the "bridge" module is connected to the SWD pins on the RA4M1, and implements a CMSIS-DAP compliant debug probe), so no special effort has been made to facilitate the use of an external debug probe.
