Remora - Rpi Software Stepping Using External Microcontroller via SPI

cakeslob wrote:

mhel wrote:

This is the beginning of my stand alone controller
what resolution is that screen you are using? 1080*640?
 

mhel wrote:

It's an 800x400, 7" it's too small if using Axis gui, but this github.com/UnfinishedBusiness/Xmotion is what I originally thought I'd use.
But I think the size is good enough for my (very distant) future DIY cnc lathe.
I'm eyeing on this one  www.buydisplay.com/10-inch-raspberry-pi-...river-board-1024x600, but budget is
a little tight right now

Cncninja wrote:

I guess i am lost a bit just like cakeslob wrote above, my understanding was the stepgen was handed off/offloaded to the microcontroller not software-driven. So your saying linuxcnc (software) makes a step pulse, sends it out well also feeding it back for a virtual encoder to see if the pulse was created. the software pulse is just passed through the microcontroller, not really generated by it. I thought the ext microcontroller was to offload the stepgen from the software where a RPI then can viably run Linuxcnc. Is this also how a FPGA like the mesa works?

In position mode, the values of maxvel and maxaccel are used by the internal position loop to avoid generating step pulse trains that the motor cannot follow. When set to values that are appropriate for the motor, even a large instantaneous change in commanded position will result in a smooth trapezoidal move to the new location. The algorithm works by measuring both position error and velocity error, and calculating an acceleration that attempts to reduce both to zero at the same time. For more details, including the contents of the control equation box, consult the code.

In velocity mode, maxvel is a simple limit that is applied to the commanded velocity, and maxaccel is used to ramp the actual frequency if the commanded velocity changes abruptly. As in position mode, proper values for these parameters ensure that the motor can follow the generated pulse train.

muvideo wrote:

Thank you Scott for your thorough reply, and many thanks also for this project.

• inversion: I still didnt update the firmware with the new content but tried to use 1 instead of "True" and indeed the inversion works correctly. 
• Steprate: ok so the maximum theoretical steprate Is coeherent with my experience, that's ok since I understand that your main target is 3D printers, the ability to use your project with a mill also very interesting. I lowered the steps per mm in the drivers configuration and lowered the maximum speeds and now the system is behaving Better. I still have to tinker with linuxcnc settings as I still have some overshoot problems.
• Feature request: it would be nice to be able to access board sd card trough USB as a generic disk storage. That would simplify initial configuration testings, for example for headless setups like mine, since I'm using vnc and the sd is not very accessible. The file would be accessibile directly trough os.

Zuo99 post=216678 userid=29932

Hi muvideo
I am also trying to use REMORA to control the milling machine, but there are still some problems. I don't know if it is convenient for you to publish and upload your ini and HAL files. At the same time, I want to know about some of your devices such as the connection of limit switches. thank you very much for your help. Zuo

{
    "Thread": "Servo",
    "Type": "Digital Pin",
            "Comment":                      "x limit and home",
            "Pin":                          "1.29",
            "Mode":                         "input",
            "Modifier":                     "Pull None",
            "Invert":                       "False",
            "Data Bit":                     0
    },

net X-min       remora.input.0  => joint.0.home-sw-in joint.0.neg-lim-sw-in