Marlin menu navigation slow while printing


My Kossel Mini printer (delta) has RAMPS1.4/Arduino Mega electronics configured to use a standard 20x4 LCD display with Marlin during printing.

Often, navigating the menus during print can be painfully slow, and I occasionally end up making the wrong selections due to lag.

Without starving the actual printing process of CPU resources, is there any way of speeding up the menu navigation?

Tormod Haugene

Posted 2016-01-14T06:54:46.547

Reputation: 3 919

What speed are you printing at? If I understand correctly, Marlin's interrupt frequency for stepping is based on the print speed (more correctly the necessary steps per second). – nanofarad – 2016-01-14T11:28:29.850

@hexafraction I don't think the interrupts are the problem, as they're very fast. The problem is that the planner is simply very slow, because delta's require complex arithmetic. – Tom van der Zanden – 2016-01-14T11:34:14.637

@TomvanderZanden Ah, I didn't realize Kossel is a delta. I should have googled first. – nanofarad – 2016-01-14T11:34:53.023

@hexafraction I added "delta" to the description so that you don't have to google next time. :) – Tormod Haugene – 2016-01-14T12:02:02.273

@TomvanderZanden, are you suggesting that it could be is the path planning algorithm that occasionally require too much processing? In that case, I believe the menus would be slower for complex movements, such as circles or polynomial paths. I will investigate that tonight, but I believe you might be right about that. – Tormod Haugene – 2016-01-14T12:20:28.787

@TormodHaugene No. Even a straight line is "complex" for a delta to print, because straight lines do not correspond to linear movement of the carriages. – Tom van der Zanden – 2016-01-14T12:32:56.887

@TomvanderZanden, you are right, of course. My bad. If I remember my radial math correctly, I believe it rather would be the other way around... – Tormod Haugene – 2016-01-14T12:42:35.833



A Delta printer requires constant complex calculations to produce straight lines while printing. The firmware, therefore, spends most of its time figuring out the step and timing sequence, and only the little remaining time between interrupts and these calculations is given to the user interface.

Marlin doesn't document any configuration parameters that would improve the user interface responsiveness, and in any case such improvement must necessarily come at the cost of printing speed and/or accuracy. The processor is being used to its maximum capacity. The only thing you might be able to do is dig into the firmware and try to change it yourself, as this is not a clear option within Marlin.

If working with the user interface while printing is important to you, your next step should probably be to change to a faster 32 bit processor. There are a few firmwares available for ARM and other architectures which may resolve your situation.

Adam Davis

Posted 2016-01-14T06:54:46.547

Reputation: 1 793

Thank you for taking your time with this. I have had this suspicion for some time, but not really known where to start. I don't think fiddling with the firmware really is the way to go, as that could be a huge time investment! At some point I might upgrade the electronics, but for now I will just accept that it is somewhat slow at times. – Tormod Haugene – 2016-01-14T16:30:02.160