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Topic: Arduino Pro Mini not at all visible to Windows (Read 4646 times) previous topic - next topic


I've had my Pro Mini (3.3V ATMega328 version) for a while but never really got round to using it. Now that I have, it does not work at all. It is simply not visible to Windows. Windows recognises the cable in Device Manager and when I connect/disconnect just the cable (with no Arduino connected) it will be added to device manager as COM3 under Ports. However connecting the Arduino makes absolutely no difference.

I've tried various driver installs/reinstalls etc and have tried everything I can think of, I was thinking it may have been a hardware issue but I do have lights flashing on the board when creating a connection between some pins meaning there is power to the board.

If anyone has any ideas they would be greatly appreciated at this point, I was hoping to start Arduino programming asap


To add, I also don't get a green LED for power on, maybe that is where the issue lies? But I've no idea how to correct it.


Do you have a programmer to burn the bootloader ?


I'm not sure, probably not. Where do I do that? If I try to burn bootloader from IDE it gives me an error with no code or extra info.


You need a programmer. I use USBasp V2. Otherse use an Arduino as programmer (ArduinoISP).
And you need wires and clips to connect the MISO and MOSI signals to the Pro Mini.

You can put this one aside, and use another Pro Mini board. They are very cheap.


Mar 10, 2015, 10:38 am Last Edit: Mar 10, 2015, 10:39 am by Wozza365
I've tried the various programmers in the IDE, none of which work because the board simply isn't recognised by Windows. Is that because I need to have those wires connected?

At this website it looks like I havent got the pins connected correctly by colour http://weworkweplay.com/play/connect-jy-mcu-usb-serial-port-adapter-to-arduino-mini-pro-3.3v-atmega328/

Could that be the problem? Do I need some extra wires to reconnect the pins correctly?

Wish I'd gotten an easier board now


That picture is for normal upload via usb-serial-RX/TX.
The extra board is the usb-serial board.

A programmer is something else.

The Arduino Uno is the easiest board to start with. But if you buy an official Arduino Uno, read this first : http://forum.arduino.cc/index.php?topic=307162.0
I think you have a bad Pro Mini, it could be a corrupted bootloader, but it could be just as well something else.
Can you buy a new Pro Mini board ?


Yes I can buy another board, I wanted to go through every option before spending more money. I'll pick one up

I have a FTDI FT232RL to connect the board to my PC, is that ok? The wires look like they are in the wrong order and are on a fixed head rather than separated.


Mar 10, 2015, 12:18 pm Last Edit: Mar 10, 2015, 12:21 pm by Peter_n
You might have a counterfeit FTDI chip, since most FTDI chips are counterfeit.
They used to work in the past, but with the new drivers, they don't work anymore.
I'm sorry, I didn't think of the counterfeit FTDI chips earlier. Most usb-serial adapters have other chips.

The usb-serial adapter boards have labels 'RX' and 'TX' but there is no standard which is which. Try RX-RX and TX-TX, but also RX-TX and TX-RX.

What should you do ? I don't know, since the problem can be the usb-serial converter or the Pro Mini or both.

Perhaps the Arduino "drivers" folder has a driver for FTDI that works. But if your FTDI chip is bricked, that won't work. It is worth to try.
It is best to start with an Arduino Uno. At this moment I advice to buy the cheapest Uno R3 clone from Ebay with CH340G chip. The CH340G needs an extra driver "ch341ser.exe" from wcn.
The Pro Mini is super useful for small projects, but it is not the best board to start with.


How do I know if its an official FTDI chip then? The cable seems to be recognized perfectly by Windows and does not produce any errors in Windows. If that is what's broken then where can I buy one from that I know will be official and work properly? The one I have now was from ebay.

I did try the driver from both the Arduino folder and the latest one from the FTDI website linked from somewhere on the Arduino site.

The reason I got the Pro Mini is because my friend was using it for his projects and I was hoping to help with more of the software side of things, however I did not anticipate so many possible hardware/driver issues. And with limited prior knowledge of Arduino, I can't really do any programming without having the device to test with.

I guess the only thing to try now is replacing the Arduino or the cable? I'll probably buy one at a time and hope that whatever I rebuy first is the thing that's broken.

Thanks for your help, I'll post back on this thread once I've replaced hardware with results.


A cheap FTDI from Ebay is counterfeit.

To start with Arduino, you should start with an Arduino Uno R3. It is the same software as the Pro Mini, they even have the same microcontroller, the Atmel ATmega328P.
When you buy a shield later on (like a Motor Shield or Ethernet Shield) you can attach it to an Arduino Uno without soldering.


I still think I'd like to stick with the Pro Mini just because of when he adds other hardware it may not work properly with the Uno properly. I know he is planning on adding various pieces but I've no idea what yet.


You can buy a good usb-serial adapter : https://www.sparkfun.com/products/12731
Or search Ebay for a cheap usb-serial that has the DTR pin : www.ebay.com/itm/181645079290

I use them in linux, and most of them work without installing something.

It could still be the bootloader or the Pro Mini is defect.
If you change your mind, you can buy an Arduino Uno, only to learn to use it. For example to test a sensor, and if it works you can add the sensor the Pro Mini and use the same sketch.

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