Re-burning bootloaders

The auto-reset is purely hardware that hard resets the ATMEL chip. It can be disabled at the other end in software by stopping the DTR signal reaching the arduino. Or it can be simply disabled in hardware by holding the Reset pin high against the best wishes of the DTR signal. Two easy ways, my preferred method is to put a 1uF - 47uF capacitor between GND and Reset which 'swallows' the low pulse created by DTR going low or the brute force and ignorance 100-120 ohm resistor between 5v and Reset. There's a destructive method which involves cutting a track or removing a capacitor from the arduino board too.

alparent: Are you saying that if I just disable the auto-reset, I wouldn't have to remove the chip on the board, I wouldn't have to change my wiring.....cause bypassing the auto-reset would cause the Arduino as ISP sketch to keep running and it would grab the new sketck and put it on the external chip (like it dose for the bootloader)?

Yes. You can use ArduinoISP to load sketches into a target system as well as loading a bootloader.

One additional thing they don't point out in the ArduinoISP documentation (along with forgetting to tell you to disable auto-reset on the host Arduino) is that the six wires you connect to the target system (Reset, MOSI, MISO, SCK, +5V, Gnd) can all go through the 6-pin ICSP connector. If you have some pin headers and an old internal floppy or hard disk ribbon cable you can make a cable that just plugs into the data and power pins on the Arduino host and the ICSP connector on the target. Just cut away all but six pins of the ribbon cable.

If you have some pin headers and an old internal floppy or hard disk ribbon cable you can make a cable that just plugs into the Arduino host and the ICSP connector on the target. Just cut away all but six pins of the ribbon cable.

I don't think that is 100% correct. The reset pin on the host is not the signal you want to wire to the reset pin on the target. It's digital output pin 10 from the host that wires to the reset pin on the target.

Lefty

Why dose the burn bootloader with Arduino as ISP work even if I don’t disable the the auto-reset?

I have been through all this many time's, i think there is something intrinsic in the Arduino as ISP Program as the developer's haven't defined to disable that.

retrolefty:

If you have some pin headers and an old internal floppy or hard disk ribbon cable you can make a cable that just plugs into the Arduino host and the ICSP connector on the target. Just cut away all but six pins of the ribbon cable.

I don’t think that is 100% correct. The reset pin on the host is not the signal you want to wire to the reset pin on the target. It’s digital output pin 10 from the host that wires to the reset pin on the target.

I’ve corrected my post above to say “plugs into the data and power pins on the Arduino host and the ICSP connector on the target.” I accidentally implied that the connection was from ICSP to ICSP. Five of the six ICSP pins can be connected straight through. The Reset pin on the target must connect to the D10 pin on the host Arduino. Sorry for any confusion.

alparent: Why dose the burn bootloader with Arduino as ISP work even if I don't disable the the auto-reset?

I don't know why it works for you. It didn't work for me: Arduino Diecimila, Arduino 22 on Mac OS-X.

It was a REAL pain to diagnose because the Diecimila bootloader acts enough like ArduinoISP (they are based on the same protocol) that avrdude saw nothing wrong until the bootloader returned 0x00 for the value of the lock byte. Took ages to figure out why the lock byte was not accepting the new value. :(

Yes, it worked! :D :D :D :D I connected up a crystal and capacitors, managed to burn a new bootloader, and uploaded the blink sketch, and IT WORKED! XD XD Thankyou to everyone who helped, I could not have managed it without you all!

Thankyou so much! Onions.

XD XD XD XD XD XD

Did you need to disable the auto-reset?

alparent: Did you need to disable the auto-reset?

I was going to, but I forgot until I was already burning the bootloader, so no.

I will test tonight If I can load sketches to the chip on the breadboard without removing the chip on the board and changing wiring. If I disable the auto-reset.