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Topic: Homemade Atmega328P-AU programmer (Read 3430 times) previous topic - next topic

SouthernAtHeart

Apr 13, 2013, 09:25 pm Last Edit: Apr 13, 2013, 09:27 pm by SouthernAtHeart Reason: 1
I read where someone put the bootloader on their SMD Atmega328P by just manually pressing/holding it on pads while the bootloader loaded.  I made this little board to do this, but before I add it to my next BatchPCB order, I had 2 questions.

I designed it where I could just plug it into pins 8 thru 13 on my UNO.  Will pins 8 and 9 supply enough current to do this task?  8 will be the ground, 9 will be +5 volts.

Also, if the connection fails during the bootloading process, does that 'brick' the chip?

thanks,

ps.  All the components (caps, crystal, and a test LED-to verify success via the blink sketch) will be soldered to the board.  Only the Atmega328P-AU will be left blank, to manually hold the chip on and bootload it.

pito

I would add a decoupling cap to VCC. Why the LED is connected to the PD3?

AlxDroidDev

I find that so risky.

Not only the risk of any discharge from your body can ruin the chip, but any minimal vibration from your hand can ruin the process.

I understand that a QFP32 socket is very expensive (shouldn`t be), but are you really willing to that that risk?
Learn to live: Live to learn.
Showing off my work: http://arduino.cc/forum/index.php/topic,126197.0.html

Coding Badly


Were I in your shoes I would...

• Get rid of the capacitor on AREF.  When burning a bootloader it serves no useful purpose.

• Follow pito's advice.  Get some decoupling capacitors on those power lines.

• Drop the crystal + capacitors.  I would use a clock signal from the programmer (are you using ArduinoISP?) instead.  Less soldering.  Fewer things that can go wrong.  Easier to fix if something is wrong.

• Have holes drilled around the target's corners so I could potentially put in "pillars" to keep the target aligned.

• Include a sketch with the bootloader that blinks the LED on PD3 as confirmation that bootloading worked.


Quote
Will pins 8 and 9 supply enough current to do this task?  8 will be the ground, 9 will be +5 volts.


There have been various problems reported on the forum when VCC / GND pins were left unconnected.  I suggest making a valiant effort to get them all powered.

SouthernAtHeart

Thanks for the feedback.  I'll update my design a little and try it out.

hiduino


I designed it where I could just plug it into pins 8 thru 13 on my UNO.  Will pins 8 and 9 supply enough current to do this task?  8 will be the ground, 9 will be +5 volts.


I think he means he wants to power the jig via the Uno (ArduinoISP) pins 8 and 9.  Probably not recommended.


Coding Badly

I think he means he wants to power the jig via the Uno (ArduinoISP) pins 8 and 9.


Ah, clever.

Quote
Probably not recommended.


Why not?  I can't find anything in the datasheet to contradict that.  The highest number I can find for current consumption is 9mA.

hiduino

I guess that would make it very convenient since it's small and compact to just plug the board into the Uno headers with just the 6-pins.  Yes, that is clever.


Erni

An alternative:

http://www.hobbyking.com/hobbyking/store/__27195__Atmel_Atmega_Socket_Firmware_Flashing_Tool.html

I have not tried it, and it seems a litle expensive

SouthernAtHeart

Edited my layout a bit, and will see how it works.  Yes the diode is for testing purposes, so I know it's flashed before soldering it on an important board.  I first designed it to sit inside the perimeter of the UNO, but then changed it so it sets on pins 8 thru 13, on the outside, with the chip on the very outside of the little 1" square board.  I have a tiny spring clamp, about like a clothes pin, I can clamp the chip on with that, visually inspect it for squareness, and flash away. 
I'll let you know how it works in about a month.

Coding Badly


Are the six through-hole pads meant to be aligned?

SouthernAtHeart

Yes. If it works, ill post more photos.

Coding Badly


Just so you know ... in the image you posted every other pad is aligned.

Jack Christensen


Are the six through-hole pads meant to be aligned?


https://www.sparkfun.com/tutorials/114
MCP79411/12 RTC ... "One Million Ohms" ATtiny kit ... available at http://www.tindie.com/stores/JChristensen/

Coding Badly


Clever.  I'll have to modify (after searching) the six-pin ISP header.  Thanks.

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