Arduino 3,3v program upload


I have stuck with a problem... So i will give a big thank to any help...

I'm building a 3,3V Arduino demo board, to use with Nokia LCD projects. I have some 328P's with 5V/16MHz loaders, which i have programmed and used previously in my 5V prototyoping board on 5V. I have built the board, put the 328 in, burnt the 3,3V bootloaer for Arduino Pro or Pro Mini 3,3V/8MHz, set the fuses. Used Parallel Programmer. Now i can upload any programs with the programmer, but nothing with my USB-TTL cable, which i use for the 5V version. I uploaded a program with the programmer, which sends data on serial port, and it worked. So serial communication is OK. I think the problem is the computer cannot reset the board. (Board hasn't got a reset button, but i will put one on it, and try...) (I added a reset button, but nothing. Arduino IDE says : avrdude: stk500_getsync(): not in sync: resp=0x00 )

Reset circuit is the same on 5V and 3,3V board (10k pullup to the VCC, 0,1uF from reset signal from the cable), and the cable is the same... Only thing i can think that the pullup resistor is different on the 3,3V version? Can it be? Should i build a level shifter for 3,3v? But serial communication works...

Thanks for any help :)

Success! There were no bootloader in it. Last night i tried to upload programs, and i forgot that at last try i used the programmer for upload, and, maybe with wrong fusing, it destroyed the loader :smiley:

Glad you got it worked out.

I have spent many a pointless half hour on a new card downloading a sketch sans bootloader and wondering why it was acting funny - finally realizing the fuses hadn't been programmed so the clock speed was miserably slow. Now I try to remember to load the bootloader (I use the IDE) no matter what so the fuses are loaded. Then overwriting bootloader with a sketch if that's what the project needs.

I had many problems with that board in the past, finally it is working now :) This is why i haven't noticed that tehere isn't a bootloader on it.

Unfortunately there is a fault, too. I tried to run the board from many 3,3V sources, but it doesn't do anything. If i connect 5V to the VCC directly to the board (without stabiliser), it works. But from direct 3,3V, don't. I tried PC PSU, and USB-TTL converter's 3,3V.

Can someone give me the correct fuse settings for Pro or Pro Mini 3,3V? I used those values from boards.txt. It can be the brownout detection?

Solved, this was caused by the wrong BODlevel. Factory setting is efuse=0x05 (BODlevel 1,8V) for 3,3V Arduino, but my one starts frm 3,3V only when BODLEVEL is diasbled (efuse=0xff) or is 2,7V (efuse=0x06). I have written these settings with avrdude on Linux, with DAPA programmer. Don't use uisp for this, it reads/writes wrong values on efuse!