ISP Programmer

Hi,
I would like to build a mega-isp standalone programmer, yet i wonder how to connect a 168/328 to the mcu running the mega-isp sketch to burn programs or bootloaders.
I thought it was as simple as connecting the miso, mosi (..) pins from one mcu to the other, but it seems a bit more like that....
I want to use a ZIF socket and therefore wonder if i need a second crystal (etc) for the second mcu or not... might someone help me with this?

Did you connect the ground as well? I haven't made a programmer, so not really sure how all that works! :smiley:

But, I'm guessing you're going to need the 2nd crystal, I don't believe the chip oscillates at the right speed. Also, with the jumper or whatever you're using, do you power the chip you're burning with the same power supply, or do you use a separate? Either way, ground ground ground! It's a must! :slight_smile:

Can you post a schematic? (It probably won't help me help you, but others might be able to point somethin out:P)

wonder if i need a second crystal (etc) for the second mcu or not...

Yes, your target processor chip should utilize an external clock source. The simplest is to use a three terminal resonator rather then a crystal and two caps. Also nice to have on the target processor board is a pull-up resistor for the reset pin (optional really but I like) and a .1 mfd bypass caps wired right to the Vcc and Avcc pins and ground.

The six pin ICSP connector will bring over the ground and +5vdc needed for the target and that should do it from the hardware side.

Here is one source for a 16mhz resonator:

Lefty

that sounds much more complicated than i thought.. do you have a schema somewhere how to build that all up?

Well this link should explain the process in general and what is needed and shows a typical schematic for a target chip:

http://www.arduino.cc/playground/BootCloner/BootCloner

Lefty

That sounds interestering... can i the target schematics for mega-isp as well? Copying the bootloader would be enough, but to have a real programmer would be far better..