I finally received the boards from the manufacturer(big thanks to @Seeed-Fusion). I manage to assemble one board by soldering the components and such and...it WORKS(including OTA)! I will post the instructions on openhardware.io project page.
In fact, the interrupt must be short enough and fast enough to be sure to not miss the RFM69 interrupts.
The code for 8 dimmers will not be really more complicated : in fact, each time we got a zero cross, we must set a timer to zero, and then wait the good amount of milliseconds to turn on the needed outputs.
So, yes, we'll have an interrupts each 10ms (each time the wave crosses the zero, to be precise !), but I think all we have to do in the interrupt handler is set the timer to zero (or to micros() ...) and then on the main loop, wait the good amount of time for each output before setting them ON.
Seems simple on paper, perhaps it will not work on the chip....
In facts, my main concern is : will the RFM interrupt be short enough to not disturb the zero crossing interrupt ?
Although, not yet tested the RFM : do we NEED the interrupt pin ? Can't we poll frequently the RFM?
Can anyone suggest a source for the parts? Are there any sources that you can upload the files by any chance?
If you mean can you upload a BOM to a company and then it generates a basket of the items, then i know that farnell and maybe digikey do this. But i only use this feature that is built into EAGLE pcb designer, so i'm not sure if they support it directly on their websites, might be worth a look.
Regarding radio's: The RFM69's with a C in the type have a smaller form factor (which is pin compatible with the predecessor RFM12B). The the 'W' and "HW' versions are larger in size and have more programmable pins (which MySensors does not use) but have exactly the same functionality within MyS.
All the footprints on the boards available in OpenHardware.io are for the 'W' and 'HW' versions so I'd go with one of these.
The 'W' uses way less power than the 'HW' which would be good the for the battery life of your nodes. Sensors powered by the grid can be 'HW', but usually, in the house a 'W' delivers enough TX power to get the message across. It might be a good idea to make your gateway with a 'HW'.
Hope this gets you a bit further. Good luck and show us your results!
@emc2 Hmm that's a pity. I could not find why specifically it was assigned to that pin other than that it is a MySensor default, so I thought maybe it can be changed (manually).
I wanted to use the WEMOS system for my nodes, not as the gateway. But if it is not possible to free up D1 & D2, there is no benefit in using them. This board is the best I could find, I would order them if D2 is freed for D4. Could you make it possible to use one of both (with a jumper of some sort) so it is compatible with either WEMOS shields, or the MySensor defaults?