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Topic: Breadboard compatbile ATmega1284P board with V-USB (Read 5888 times) previous topic - next topic

ralphd


Also, if you have the right tools (hot air) replacing an SMD package is not that big of a deal.

I guess it's worth a try.  Any tips for avoiding solder bridges when dealing with 0.8mm pitch QFPs?
My other problem is the pro mini is a bit more cramped than your board layout, so removing the QFP will be difficult without bumping an adjacent resistor or cap.
Unthinking respect for authority is the greatest enemy of truth - Einstein.

TheCoolest

#16
Jan 05, 2014, 09:39 pm Last Edit: Jan 05, 2014, 09:42 pm by TheCoolest Reason: 1
Do you have a pic\link to the Pro boards? Either way I really don't think it's worth replacing the ATmega on these, as it's cheaper to just replace the board itself than mess with replacing the MCU.
With a hot air smd rework station you can remove chips pretty easily. And if you get some solder paste, soldering one back in place should be just as easy. I don't have one yet, so I'm using a 936 soldering station, with the right tip and 0.5mm (or thinner) solder it's not too hard. Removing a chip is very difficult with just a soldering iron, but there are kits for that like QuickChip.
DIY boards are tougher to solder to as they don't have a solder mask, but the boards I've got do, so soldering to them is piece of cake. Good flux and solder wick are also good things to have.

ralphd


Do you have a pic\link to the Pro boards?
...
Removing a chip is very difficult with just a soldering iron, but there are kits for that like QuickChip.


Here's the pro mini I smoked:
http://www.fasttech.com/products/0/10004915/1380906-pro-mini-microcontroller-circuit-board-module

I've since ordered another from a different supplier for $3.65 shipped, and if it works well I'll be getting a batch of 10 for $2.57 ea.  I may still try replacing the chip just to see if I can do it.
As for removing the chip, one guy told me he cut a SOIC-8 Tiny85 off a board with a utility knife.  The leads on that are bigger than the qfp32, so I've been meaning to try it on the pro mini.

Unthinking respect for authority is the greatest enemy of truth - Einstein.

TheCoolest

That's right, you can cut off the pins, and then remove them with a soldering iron.
I forgot to mentioned that because I really wanted to remove my 328p without damaging it to test it on another board.

I think that PRO board should be doable using a soldering iron, just may need a thinner tip on some of the pins.

ralphd


That's right, you can cut off the pins, and then remove them with a soldering iron.

Turns out to be pretty easy with a cheap utility knife aka box cutter (photo attached).
I am a bit concerned I may have accidentally cut one of the traces that runs underneath the chip though...
Unthinking respect for authority is the greatest enemy of truth - Einstein.

ralphd

But it turns out the circuit board pads are very fragile.
Unthinking respect for authority is the greatest enemy of truth - Einstein.

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.

ralphd


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.
Unthinking respect for authority is the greatest enemy of truth - Einstein.

rpeter


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 can`t 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 didn`t do anything and don`t have any idea)
rpeter

TheCoolest

#24
Mar 18, 2014, 09:16 pm Last Edit: Mar 18, 2014, 09:20 pm by TheCoolest Reason: 1
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?

rpeter

#25
Mar 19, 2014, 06:05 am Last Edit: Mar 19, 2014, 08:27 am by rpeter Reason: 1

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?

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.
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

retrolefty

#27
Mar 19, 2014, 01:53 pm Last Edit: Mar 19, 2014, 02:26 pm by retrolefty Reason: 1

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.  ;)

TheCoolest

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.

rpeter


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

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