Uploading to Pro Mini fails with FTDI

[ben999]

Hi,

I am having trouble uploading sketch to Pro Mini.

This is new behaviour as it used to work a few weeks ago.

I am using this board : https://www.ebay.com/itm/FT232RL-3-3V-5-5V-FTDI-USB-to-TTL-Serial-Adapter-Module-for-Arduino-Mini-Port/381374421597?epid=502148532&hash=item58cbafda5d:g:jk8AAOSwrklVMjIp

Works fine when it powers the Arduino (ie all 6 pins connected between FTDI and ProMini)

In a fairly recent past i could also upload sketch when having the ProMini powered via an external power source. In that particular case, i would not connect the Vcc pin of arduino to FTDI board, and still power the arduino via its "normal" power source (batteries). Serial monitor would aslo behave perfectly.

I have spent some time lately working on hardware (aluminum and carbon baby!) for MySensor project... now that it's time to put all that to life i am facing that problem : no more uploading with external power source.

Same result with Win10 computer and Ubuntu16 laptop.

What would happen in case i keep ProMini still powered via batteries while plugging FTDI board WITH Vcc ? (i do that with Uno and Mega but i know for sure these are designed this way. Not sure about Pro Mini though)

Thanks a lot for your input

Best Regards

[rejoe2]

OK, there seem to be others out there with similar problems, and I'm rather sure, the hardware I used the last days was also working before...
Can't test it, but this may be related to the recent changes in boards.txt (did you do any updates on that the last days?):

https://github.com/arduino/Arduino/commit/1cf34c8250658c5c4a5c488f7a7a0d7071e3430f#diff-4ead488680453362ffec01d74609315c

So you may either try to use the "old bootloader"-Variant (didn't work for me), try to upload a different bootloader or try, if changing just the upload speed back to 57600 Baud may help.

Good luck and keep us updated how you solved that problem!

[gohan]

what is the voltage supplied by batteries when you are trying to upload the sketch?

[ben999]

Hi @rejoe2

Thanks a lot for your reply

That is indeed a starting point, thank you very much

Your explanations sounds a bit like foreign language to me this problem will hopefully take my knowledge one step up as i have never faced the need to play with "bootloader", "fota" and friends

I sure will keep you updated about my findings!

[ben999]

Hi @gohan

2x AA. Same as before. I tried new batteries to be sure

[gohan]

there is a limit in voltage difference between vcc and GPIO pins, can't remember now exactly but it could be a cause.

[petewill]

@ben999 I think I understand what you're asking. If so, I do it frequently with my projects. What I do is just unplug the VCC DuPont cable from the FTDI adapter. Here is a picture of what I mean.

[ben999]

Hi @petewill

Thanks a lot for your suggestion (nice picture BTW)

This is exactly the way i (used to) do. But sadly it doesn't work anymore. I can only upload sketches with VCC connected and external power source disconnected. (what would be the outcome in case i leave FTDI's Vcc AND external power source connected to Pro Mini?)

So it is for now impossible to get the serial monitor feedback while using the node in real-life condition...

[gohan]

Maybe nothing maybe something could get fried. You could still make a SD logger that @sundberg84 published on Openhardware.io

[mfalkvidd]

@petewill I have something that might make things even easier: wouldn't you get the same result by removing the 5/3.3V jumper on the ftdi?
EDIT: No, not a good idea (see discussion below)

[gohan]

That jumper should also set the logic level of the data pins, doesn't it?

[mfalkvidd]

@gohan good point. I guess the best way to figure out is to bring out a multimeter.

[Yveaux]

@gohan said in Uploading to Pro Mini fails with FTDI:

That jumper should also set the logic level of the data pins, doesn't it?

Typically, from my experience, that jumper only sets the logic level of the serial interface. The VCC pin stays at the USB supply level, so around 5V.

Update: Apparently the Sparkfun board does also change the VCC level (ref: https://learn.sparkfun.com/tutorials/serial-basic-hookup-guide)

Conclusion: Better check with your board!

[gohan]

I used it to program my sonoff and it didn't fry it so it also sets vcc to 3.3v

[Yveaux]

@gohan said in Uploading to Pro Mini fails with FTDI:

I used it to program my sonoff and it didn't fry it

That's one way to find out

I just want to stress there are multiple designs out there (also with FTDI alternatives) and it's better to be safe than sorry.

[mfalkvidd]

I checked my FTDI adapter. The jumper does switch both Vcc and logic levels, so removing the jumper is probably a bad idea.

[gohan]

@yveaux I know, I fried a sonoff with a supposedly "universal" ftdi adapter

[dbemowsk]

I have all my FTDI adapters set to 3.3v. I too use them to flash my sonoff modules, and those WILL fry if you try to flash them with 5v. My pro minis flash just fine at 3.3v.

Some time back before I got my Vera controller I tried using an FTDI adapter for my gateway and could not get the thing to work. Testing it, I found that my TXD line was transmitting, but my RXD was not receiving. Check that you have communication in both directions.

[petewill]

@ben999 Sorry for the delay. Work has been crazy lately. I see there are plenty of answers above and I echo them. I try not to upload with two power sources connected. If everything is 5v you are probably safe but I see you're using batteries and I'd not risk it just to be safe. I have used two power sources in the past but I have since changed my ways. I can't remember what stopped me but I believe I was getting strange results. I don't think I ever fried any hardware but why risk it...?

If you are still having this issue have you tried with another Pro Mini and different code? Is anything coming out of the serial monitor or is it just blank?