Atmega 328P U with ft232RLN communication problem

Hello everyone

I try to make a custom board with atmega328pu and an FT232RLN to program with usb.

I successfully set the new atmega328p chip, but after that, when I want to upload a new program (like blink), the TX led of the FT232RLN blinks, but not the RX. It seems atmega328p not responding.
I get this error on the arduino IDE :

avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x3c
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x3c
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x3c```

I already tried to test USB communication (with shunting RX and TX) and I successfully received back what I send via the serial monitor.
Also, when I program the atmega chip on a genuine arduino uno and I replace the chip on my custom board, the program work (blink)

So for me, there is a link problem between the atmega chip and the FT232RLN or something I need to set on the arduino IDE to be able to upload ? (I use AVRISP mkll programmer)
Bellow my schematic.



https://ibb.co/JzKSNxC
https://ibb.co/vYn8NW7

Thanks for your help.

Did you burn the bootloader on the 328?

Yes I did
I also tried to put an old atmega chip (same reference) on the custom board, but same problem, unable to program it

We need to see a schematic

I tried to put it directly, but something strange happen... so I put a link to open it in another website...

No link here

these

Too difficult to read with two links.
You need to post the complete schematic here.

very strange... i don't know why I can't add it to my main post... I had to use reply for it to work...

@tonynyny I'm out of time for today, hopefully someone else will reply.

Try holding the reset button, start the upload from the IDE and quickly release the reset button.

If the doesn't work, then all I can say is hook up you scope and start probing.

Check the TX pin at the 328 then at the FT232 RXD pin.

It doesn't work, As fast as I can, the IDE detects that there is nobody on the COM, so can't go further for uploading...

What do you recommand to check if the TX pin of the 328 works ?

So I upload a simple sketch on the 328 with the arduino genuine pcb (sending 'A char' to the serial port every 2 second).
After putting the 328 in the custom PCB, I see that the ft 232 RX led blinks every 2 second, so I suppose that the problem come from the ft232 communication...

Maybe a special config I don't know...

Remove the 1K pull-down on the FT232 DTR output.
It's preventing the DTR from going high

thank you @jim-p problem solved with two things :
1 - Before "burn bootloader", select arduino nano board (Arduino as ISP for the uno master)
2- I sold the D3 diode in the wrong way, so after correct it, everything goes fine !

Thanks again for your help

Glad you got it working.
Things in backwards, not an uncommon mistake.
Have fun

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.