Arduino pro mini uploading not working

Development Tools Uploading
1

Hi, I have a problem with uploading code to arduino Pro Mini. I have read all the discussions and tried what I could think of.

I don't understand it anymore.

I have several Pro Mini's and several TTL USB converters to test. It always behaves the same or very similar.

The first upload to the new Pro Mini works and the program loads and everything works via TTL USB. I have a CP2102 and a FT232R. I think I have had more successful experiments with the FT232.

I thought that somehow the bootloader got corrupted after the first program upload, so I tried uploading a new one via UNO as well. I tried loading the program directly into memory via UNO and also apparently without success.
I have tried all the variations with holding reset, but to no avail.
Yesterday, with my new Pro Mini, an error popped up that COM9 was not accessible. After several attempts, the program loaded fine and when I tried to load the program again a few minutes later, all I got was an error

avrdude: stk500_recv(): programmer is not responding


zde napište nebo vložte kód

and I'm not going anywhere. What helped after the error COM9 not accessible error was to restart the PC.

This morning I desperately turned on the PC and tried to load the program. No changes in the program, no changes in the wires. Nothing at all. I just turned on the IDE and connected the TTL USB with the Pro Mini and the program loaded on the first try. But the second try doesn't work again even if I replace with another pro mini.

I don't understand what is going on.
Is anyone able to help me?

Thank you

2

I am going to need some more details.

First of all which type of Pro-Mini do you have ? is it the one with 16MHz Oscillator(marked 5v) or 8MHz Oscillator (marked 3.3v) and with which processor (328p or 168)

Which are the uploaders you have tried and how have you wired them up ?

How have you connected the UNO + Pro Mini to burn a new bootloader and what are the settings you have used for that ? If you are using the UNO as ISP, you need to upload the sketch from Examples->ArduinoISP->ArduinoISP And Set the programmer to Arduino as ISP under Tools->Programmer->Arduino as ISP

I program Pro-minis using an UNO as a USB to TTL, but as not to confuse the issue i will leave those instructions out for now.

3

It is 16 MHz 5 V version. I tried CP2102 and FT232

I use this manual for upload bootloader. https://www.instructables.com/Burn-a-New-Bootloader-Arduino-Pro-Mini/
UNO like ISP, sketch Arduino ISP was in UNO,

IMG_20250318_083000
IMG_20250318_0830001920×1440 95.9 KB

4

It leaves me with a bit of an impression as if the USB TTL converter can't see the connected arduino for the mini. I can't even see the RX/TR flicker on either side. If I disconnect the arduino from the TTL the resulting error is the same... the programmer is not responding. Like there is some miscommunication here, but why does it sometimes go? I try another laptop of a different statement and same problem. I'm also trying the older IDE 1.8.18

5

Looks like you have that wired wrong.
All six connections should be made.
Just connect the pins on the mini to the FTDI straight across

Mini -- FTDI

GND  -- GND
GND  -- CTS
Vcc  -- Vcc
Rx   -- TX
TX   -- RX
DTR  -- DTR
6

I tried that, too. That's not my problem. One morning the program loaded in this wiring and nothing since. This is not the solution.

Now I have identified that uploading the program to the Pro mini mega 168 5V 16 Mhz, version works if I choose the correct processor .

For the 328 P 5V 16 MHz version even if I choose the correct processor it does not work.

7

It's the correct way to connect them.
If that does not work then you may have damaged the FTDI or mini.
You can try a loopback test on the FTDI board using a program like putty.
Connect the RX to TX and disable the local echo in putty

8

That could be a clue. I can't test it. But it's unlikely that I have 3 faulty new TTL converters or a problem on the device when testing on two laptops from different manufacturers.

I'm testing different TTL converters and it doesn't work. But at the same time I have verified that the converter works because as I wrote above uploading the program to Mega168 always succeeds and I have limited the problem to Mega328P

Maybe some missing support for Mega328P?

9

If you push the reset button on the mini does the LED blink a few times (I think 3)?
If not then the bootloader is missing or corrupt.

10

On the mega168 on which the upload works, the LED flashes once.

On the mega238P on which the program cannot be loaded, the LED flashes once.

11

Some Pro Minis, from China maybe, come fitted with an ATmega168.

I had one once, chucked it in the bin.

12

Yeah. I'm going to throw it away too, but now I've found out that the problem is not USB TTL because 168 upload works. Only the 328 upload doesn't work and I can't think why.

13

Either it has the old 168 bootloader or it's bad.
I have no other debugging suggestions.

14

This is not clear to me. Do you just change the settings or do you have different Pro-mini boards.

Can you read what is actually written on the MCU ?

15

I apologize for the lack of clarity.

I have two Pro Minis. I thought they were the same and I recorded the program the same way. I used an ATmega328P 5V 16 MHz processor in the ID and could not load the code on either board.

A while ago I found out that one board bought in China has used Mega168 so I tried in IDE to change the processor to ARmega 168 5v 16 MHz and the upload works.

So I found out that I don't have two identical Pro Minis. But the problem persists as I am unable to upload the program to the more modern version with the 328P chip on the board. Because of the memory size I need this one.

However, the fact that it works to upload to the version on the board with chip 168 perhaps rules out a USB TTL or wiring error.

For some reason unknown to me, I am unable to load the program into the PRO MINI version with the 328P 5v 16 MHz chip even though I have the process set up correctly in the IDE. Uploading the program to the 168 5v 16 MHz when I set up the correct process works.

I tested that after reboot both boards flash once.

16

And i guess you have tried to burn the bootloader again to this board ?
Any chance that it does not have the oscillator you have selected in the IDE on the board ?
It could just be bricked because of that, but un-bricking a 328P is not an easy task.

17

I tried using these instructions to reload the bootloader yesterday. But if the bootloader was the problem, the upload could not work once this morning and then nothing again. :frowning:

I'll try again to reload the bootloader.

18

How's the soldering of the pins?

19

Yeah i think that instructable does the job, the connections are the same as inside the ArduinoISP sketch. Either there is something wrong with the fuses or there is a hardware issue somewhere. Have you tried re-soldering all the header pins (just heating them up until the solder flows)

20

I don't believe it! The badly soldered connector was a mistake.

Thank you. 3 days of misery and so many hours of work. Hopefully the discussion will be helpful to others.

I tried not to overheat the board when soldering and that was probably a mistake.

Thank you to an amazing community.