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Topic: 2560 bootlader mkii problem (Read 1 time) previous topic - next topic

CrossRoads

Reset is supposed to hold the Reset pin high.
When its low, the uC is in reset.
The AVR ISP controls the reset pin during the bootloading.
It should go high when the bootload is done for normal operations.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Houser636

I see what you mean the programmer controls the line.  I tried using the uno as an isp, and coudnt get it to work either.   It works on a known good 2560, but not my board.  I just do not understand why it wored until i tried to bootload it and now nothing. 

I guess i will order another chip and try again.

Any other ideas?

CrossRoads

NickGammon has the Uno as bootloader part worked out quite well, including bootloading a 2560 board from an Uno.
Have you tried that?
http://www.gammon.com.au/forum/?id=11635

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Houser636

Yeah thats exactly what i tried.  It wouldn't get past the beginning of the program where it pulls the reset line low, and checks for clk.

I put my multi meter on reset and ground right at the pin.   It went to about. 02v. I did it with a known good board and ot went down to .005v. Do you think yhis is enough to cause the issue?

Houser636

#19
Aug 04, 2012, 06:11 am Last Edit: Aug 04, 2012, 06:15 am by Houser636 Reason: 1
Problem Solved!  Thought I'd let everyone know just in case they are having a similar problem. It was the reset line.  I made one on a breadboard going from 5v to a 10k resistter.  the resistor goes to the reset switch + side.  The other side straight to gnd.  right after the 10k resistor, I put a 22pf cap.  Everything works perfect.  Bootloader uploaded fine.

Thanks everyone that helped.

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