Breadboard compatbile ATmega1284P board with V-USB

But it turns out the circuit board pads are very fragile.

Ouch. What temperature did you set your soldering iron to? When cleaning the pads you should use as low temp as you can get away with, using a lot of force pushing down on the pads is also a no-no. The solder mask on that pcb looks fried.

TheCoolest: Ouch. What temperature did you set your soldering iron to? When cleaning the pads you should use as low temp as you can get away with, using a lot of force pushing down on the pads is also a no-no. The solder mask on that pcb looks fried.

It's an uncontrolled 35W soldering iron. I think my mistake was putting too much lateral pressure on the lead ends when trying to unsolder them. The mask is fine; I hadn't cleaned the tip well and there was some carbon on it that mixed with the water-soluable flux paste I had put on the board; I was able to rub the dirty residue off with my fingernail (not that it matters much since I broke off the two pads). Also if the traces to those pads came from under the chip I may have accidentally cut the traces when I cut the leads off the chip.

TheCoolest: I finally figured out what was wrong with my attempts to get the USBasp bootloader to work correctly on this board, fixed it and now sketches can be easily uploaded to the board directly via USB.

Hi, a weeks ago, i tried to implement an usbasp to this avr, but unfortunately i cant did it. Could you help me, please, which is the problem in the "original" code? (i changed the pins and add the signature, the gcc was translate it, but the code didnt do anything and don`t have any idea) rpeter

Did you use USBasp or the USBasp-loader? If you used the loader, did you burn it as a bootloader to the chip or just as a program? did you set the appropriate bootsection size fuses?

TheCoolest: Did you use USBasp or the USBasp-loader? If you used the loader, did you burn it as a bootloader to the chip or just as a program? did you set the appropriate bootsection size fuses?

The v-usb based usbasp bootloader, which i used earlier successfully some 328p, burned with a dopper by a modified makefile. Yes, i tried with 2k and 4k bootsize too, set the bs start address in byte base (1f000 or 1f800). A simple blink prg is working correctly. Unfortunately i havn`t any idea, which is the problem... Maybe could you send me the modified part of the code, please?

What programmer are you using? For example ‘USBTinyISP’ won’t work, as it doesn’t support devices larger than 64KB.
I successfully used USBASP and ArduinoISP to burn the bootloader to the chip.
I’ve attached the modified files, they aren’t final, but should work.
You will need to pull PB2 down to activate the bootloader, or change the port/pin in bootloaderconfig.h

USBaspLoader.zip (115 KB)

TheCoolest: What programmer are you using? For example 'USBTinyISP' won't work, as it doesn't support devices larger than 64K. I successfully used USBASP and ArduinoISP to burn the bootloader to the chip. I've attached the modified files, they aren't final, but should work. You will need to pull PB2 down to activate the bootloader, or change the port/pin in bootloaderconfig.h

I don't think that is correct. I too have a USBTiny ICSP and playing with a mega1284 chip believe I could fill the whole 64K WORDS of the flash memory, which is 128KB flash size. AVR word instructions are larger then bytes. It's the mega2560 chip that has too large a flash size for the USBTiny.

At least that is my memory but it's been a while and I keep lousy notes. ;)

I tried it with USBTiny and it didn't work. I also read that some people got it working with USBTiny's but I wasn't able to get it working.

TheCoolest: What programmer are you using? For example 'USBTinyISP' won't work, as it doesn't support devices larger than 64KB. I successfully used USBASP and ArduinoISP to burn the bootloader to the chip.

Many thanks for the source and for your help. Currently used an avr doper (stk500v2 compatible v-usb programmer), but if i can't use your code, i will try to do it with a raspbian pi gpio port as an spi based programmer

Was wondering if there was any interest in this board. Here's the new 2nd revision up and running (minus the 3.3v level shifter, don't have any more 4050s on hand)

Running an Arduino sketch to test whether it's working as planned or not:

All the specs of the 2nd revision is in the first post on page1.