I have a 12V 20A power supply that I purchased many years ago for a Prusa i3 that I never got around to building. Is this ok to power up the SKR PRO1.2 ( I notice Ryan sells a 12V 6A brick )
Will 20A damage anything ?
note: In this video there are two power supplies incoming. 1 to drive the board and another to drive the stepper motors.
While I’m messaging… I notice I still have the Prusa i3 board… (an AtMega1284P) that comes with Marlin installed) I wonder if this would have powered a LR2 ?
You should be safe with the PSU you have… the amp rating is the max the unit can supply, but the actual amount supplied will be based on the load connected to it.
If the board can run marlin it probably could run the LR2 but 1284p is pretty slow compared to the 32 bit boards in use now.
Regarding the power supply… So in general the board draws whatever amps required depending on workload at any given time right? So a higher rated amps only pulls what’s required… Ok got it.
As for the ATMega1284 board… yes true would run really slow. Perhaps I save it for another project
Correct, so for instance it will draw some amount of current when just the board is on, and will draw more once the steppers turn on. So as long as it never tries to draw more current then the power supply can supply, your golden.
You can always give it a shot, not like it costs anything to try. I would just plan on wanting to upgrade it in the near future. I intend on using a board out of a creality cr10 for my build because I got it for free the important part is to have fun and learn from it
No. But there aren’t a whole lot of operations that need extra speed. For example, the reading of the gcode over serial happens at 250k baud rate on either board. The speed the motors step is the same and the math to determine how fast to step is the same.
There are some corner cases where it matters. If the incoming gcode has an arc, the math to convert that arc to movement is faster on the skr. As long as the 8 bit board can compute it faster than the bit is moving, it won’t matter. Marlin has a few settings to determine how that arc calculation is done and we have tuned the settings so the arcs are computed fast, and the arcs have no artifacts. If we had a 32 bit board as baseline, that tuning would probably have been easier.
I’m not sure if the skr has a larger planner buffer size. I’m also not sure if it can read gcode from the sd card any faster.
Not unless you are extruding. I haven’t ever seen an issue with linear advance on my printers. I have 2 that run on 8bit boards with linear advance enabled.
Thanks for the replies… I’m not 100% sure what the heck you guys starting chatting about there so instead I’ll just nod my head in appreciation like I totally get it.
the important part is to have fun and learn from it 
