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USB AVR Programmer v2.1 doesn't work

I found one issue with a USB AVR Programmer v2.1.

When all I/O pins are only used for connections to the programmer, it works correctly. However, when some I/O pins are connected to other things such as LEDs, it does not work.

I managed to solve this issue. I thought its cause is 470Ω resistors. They may divide voltage and the signals are not transmitted properly. Then, I removed 470Ω resistors which are connected to I/O pins and shorted each of them. After that, I could write data to my AVR by using the programmer.

Also, I have a v2(not v2.1) programmer which works correctly even when LEDs are connected to the I/O pins. The v2 one has 470Ω resistors which the v2.1 one has. So I think the resistors are not the real cause.

Please inspect the v2.1 issue.

Hello.

We have not seen or heard of anyone having that issue before. Do you remember any details about the behavior you saw from the Programmer v2.1 before you removed the 470 Ω resistors? How were you powering your system while using the programmer? What device were you programming and what was it connected to? What other things were you connecting to your programmer’s I/O lines, and how were they connected? Could you post a screen shot of your programmer’s configuration utility while it is connected to the programmer with the settings you were using when it was not working as well as pictures of your setup?

-Patrick