Issure with uploading program to ATmega328P

The bootloader is uploaded to the ATmega328P succefully, but when I connect the ATmega328P to an Arduino UNO through RX TX ports the IDE tells me this,


I have checked all the wire connections etc. and nothing wrong. There are only 4 wires connecting the board, 5V, GND, RX, TX.
Arduino UNO is also tested with its original processor, blink can be uploaded to it so its working fine.
Any suggestions on this weird issue?
Thanks in advance!

We need to know the ATmega328P's circuit, including the exact connections between the Uno's pins and the ATmega328P's pins.

Please tell us how you have the Uno configured. There are multiple possible approaches for using an Uno as a serial adapter for another board. For example, some people even remove the ATmega328P entirely from the DIP socketed style of Uno.

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When you programmed the bootloader, which board was selected?

If the chip has an Uno bootloader, select the Uno under the tools selection. You currently have the Duemilanove/Diecimila boards selected which, IIRC, use a different (slower) baud rate than the Uno which could cause the problem you have.

Yes thanks for replying, I did remove the ATmega328P entirely from the UNO. I was basically following this tutorial:

And as it is shown in the steps, I integrated the resistors and stuff on my board. So I connect exactly as it is shown with only 4 wires, RX TX 5V and GND to my UNO.

Ah I see that might be the problem. So if I burnt the bootloader using the default example "Arduino as ISP" file, and upload using board: Arduino UNO with programmer Arduino as ISP, do I still use the exact same sets when uploading the programs?
Do I need to switch the programmer to the normal AVRISP mkll?
and Also do I upload the program normally with the upload button or should I upload it using "upload using programmer" ?
Thanks a lot!

Yes. With a bootloader installed, you use the upload button, not upload with programmer. If you upload a sketch using any ISP programmer (Arduino as isp included), it will upload your sketch but it in the process, it will erase the bootloader

The bootloader is what allows a program to be loaded using just a serial/usb port. Without a bootloader, you must use an ISP programmer.