Hi, I've recently been looking into setting up my own CNC Electronics. The first question I've got is over latency performance. I know the Beaglebone AM3358 has a single core 1Ghz Arm Processor and 2 x PRU's running at 200Mhz For the Rpi3 it has a quad core 1.2Ghz Arm Processor - BCM2837 - A53
Now I know that one of the ways machinekit gets low latency is to use the PRU's for dedicated motion control on the BBB. But I was wondering if the Pi3 had one of it's cores dedicated to the Operating system and the other 3 somehow dedicated to motion control then how would this compare. One difference the PRU has is that it's instructions take 1 cycle to complete, but on the other side the Pi3's other cores are running at around 1000Mhz faster with 3 available. Is this a supported setup from machinekit's point of view (has someone already done this?) The next question I've got is regarding hooking up the control board to seperate stepper driver boards etc. I know one of the downsides of an Rpi3 is the GPIO count, so I started looking into different options I liked the look of EtherCat but I think there's no open source hardware shields and most of them just appear to use a netX52 to fire SPI data over Ethernet. Since the boards I'm planning on using will all be in the same shielded case I figured I might just try a shielded SPI cable to each slave board. There's some discussion online over what the max SPI speed is for an Rpi3, theoretically 125Mhz although I've not tested that yet. My plan is to use some TMC2660 Stepper drivers that can give a smoother waveform (quieter) and provide feedback on the amount of force the stepper motor is using, with an auto cut off if the force goes over a certain limit. If I were to try something like this then I'd guess I'd have to write some custom HAL modules etc. But I wanted to get any comments first from the folks here as to what they're thoughts might be for the hardware. Also btw I think the search box is broken on the machinekit website Many Thanks Richard -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. Visit this group at https://groups.google.com/group/machinekit. For more options, visit https://groups.google.com/d/optout.
