> From: Jon Elson [mailto:el...@pico-systems.com] > On 04/29/2020 12:54 AM, John Dammeyer wrote: > > > > Here's my question for you. If the asynchronous pulse > > generator from your $1 chip has just created a pulse and > > the SERVO_PERIOD now wants to a new rate how do you set up > > the frequency generator so that the next pulse is > > correctly spaced from the previous one? Or do you just > > hope it works out? > The trajectory planner uses a specified acceleration rate to > change the commanded velocity in small increments. Remember > this is typically recomputed 1000 times a second. So, there > will not be huge jumps in commanded velocity. Therefore, > the change in time between steps will not be large, so the > motor can follow it properly. > > Jon
Thanks Jon, My ELS included most of that trajectory planning, step pulse generation and the LMD18245 micro-stepping control all inside what would be called the BASE_PERIOD thread in LinuxCNC. That's because 14 years ago two LMD18245's and the associated parts cost less than any 3A 55V micro-stepping driver out there. Now you can get that for the price of only one LMD18245 so that hardware is redundant. Which means I've been rethinking how I'd do things. Interesting too how motion.c which I'm seeing for the first time is very similar to what I did in my ELS code. I've ported the ELS from the PIC18F to a PIC32 and for the most part it's working. And that interrupt routine that used to take about 35 microseconds now takes under 2 uS. And I want to run everything under the PIC32 version of FREE RTOS. John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
