Is it possible to program/put loader on multiple Atmega ICs at one go? Like wiring them up in parallel ? Like say i short the corresponsing icsp pins of all ics to be programmed and then program them? anybody tried this?
From what I understand, that will not work.
I really don't know if it would work, but I think there are two ways that it might work:
1: this is an easy way, but I'm not sure how likely is it to work, if it does, it would only work if all target devices are the same AVR and possibly from the same batch (so they have almost the same characteristic and minimal variation). Basically you need to use serial programming interface (ISP) and connect all 6 pin required for the programming to all AVRs, except connecting MISO only to one of the AVRs, and not to all. This way is assuming all AVRs luckily are taking same amount of time to program (that's why they should be from the same batch), and if one responds with ready or busy (or any other response) they are all in the same state.
I'm not very optimistic for this to work.
2: make you own custom AVR programmer (I did it once a few years ago, and took me less than a weekend to program and test it- I used another AVR to make this)
connect all the pins connection as you would do for a single chip, except have MISO pin from each AVR going to a separate input on your custom programmer. and from there handle waits and delays so all AVRs are ready for programming. for example if you program a page, wait for response from all the AVRs to ACK before programming next page. or if you have to reprogram a page on 1 AVR, reprogram them on all.
I'm very optimistic that this would work, but wouldn't be a simple solution.