anybody saw this? and is trying something printee on it lol? [www.kickstarter.com] https://reprap.org/forum/read.php?2,195973,195973#msg-195973 Sat, 06 Jun 2026 06:08:18 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?2,195973,240472#msg-240472 https://reprap.org/forum/read.php?2,195973,240472#msg-240472 -------------------------------------------------------
> Open loop PWM is only accurate when the motor is
> moving slowly. You need to measure the coil
> currents like chopper drivers do to get accurate
> microstepping during motion when the generated
> BEMF and inductive BEMF have a large effect.

Good point but I noticed that at least one of the currently used firmwares only does partial intermediary position calculations and assumes that the motors will follow correct paths between calculated xyz coordinates. On a Delta this could give some odd build grain. Slicer configurations can generally compensate for lead/lag by creating gcode requests for slower motion in the build portions with high acceleration/deceleration forces. I expect a good test would be to compare parallel 45 deg lines drawn in opposite directions at fixed distances apart with the same mechanics but different hardware, i.e. chopper drivers vs open loop PWM drivers.]]> grael Developers Wed, 28 Aug 2013 05:59:13 -0400 https://reprap.org/forum/read.php?2,195973,239820#msg-239820 https://reprap.org/forum/read.php?2,195973,239820#msg-239820 nophead Developers Mon, 26 Aug 2013 07:55:54 -0400 https://reprap.org/forum/read.php?2,195973,239793#msg-239793 https://reprap.org/forum/read.php?2,195973,239793#msg-239793 I have an STM32F103 (Arm Cortex-M3) based board I built for 3D printing and it's pretty fast already. STM do a Cortex M4 that would do everything my one is, even faster and with time spare for other things. The chips in common use in the popular 3D printer PCBs these days already do much of the work my cortex chip is doing, I only needed a fast chip because I'm directly controlling the coil polarities and doing microcontroller controlled PWM. Oh.. and I modified it to do delta calculations too.

The cortex M4 is plenty fast enough...

Graham.]]> grael Developers Mon, 26 Aug 2013 06:51:21 -0400 https://reprap.org/forum/read.php?2,195973,201262#msg-201262 https://reprap.org/forum/read.php?2,195973,201262#msg-201262
As for the FPGA, im actually working on something like this already.. basically for fun purposes only. if someone does feel like teaming up then let me know! but dont expect much from this.. i dont expect FPGA to be able to swap the MCU for this purpose - its too complex.]]> badmanjoe Developers Fri, 19 Apr 2013 18:33:05 -0400 https://reprap.org/forum/read.php?2,195973,198548#msg-198548 https://reprap.org/forum/read.php?2,195973,198548#msg-198548 There are open source FPGA stepper motor projects. Open Cores has open FPGA projects to suite most tastes.
Here is a link to a stepper motor project: [opencores.org]
I see that they say it is a beginner project;)]]> SouthT Developers Tue, 09 Apr 2013 11:33:59 -0400 https://reprap.org/forum/read.php?2,195973,196977#msg-196977 https://reprap.org/forum/read.php?2,195973,196977#msg-196977 Simba Developers Tue, 02 Apr 2013 23:05:43 -0400 https://reprap.org/forum/read.php?2,195973,196641#msg-196641 https://reprap.org/forum/read.php?2,195973,196641#msg-196641
One drawback to FPGA development is the lack of open source tools for them, they tend to be proprietary and manufacturer specific. I think there has been more interest in FPGA recently, maybe due to Bitcoin miners.

I draw comfort from Linux, it is a complex piece of software, and competes with billion dollar corps like Microsoft. In the case of Android, it beats Microsoft's offering and possibly Apple as well.

Cypress have some chips which combine ARM cpu with programmable logic blocks, also Microchip have some PICs with simple configurable logic cells. If these trends continue, we might see more CPUs with ability for programmable peripherals, and get the best of both worlds.]]> bobc Developers Mon, 01 Apr 2013 14:14:25 -0400 https://reprap.org/forum/read.php?2,195973,196606#msg-196606 https://reprap.org/forum/read.php?2,195973,196606#msg-196606 redreprap Developers Mon, 01 Apr 2013 12:26:47 -0400 https://reprap.org/forum/read.php?2,195973,196289#msg-196289 https://reprap.org/forum/read.php?2,195973,196289#msg-196289
Only thing is, FPGAs are not cheap. For the price of the Spartan 6 FPGA you can get a Cortex-M4 running at 150MHz with change, so if you were going to create a dedicated solution with an FPGA, it seems to be more useful and probably as effective to create one using an MCU instead.

I noticed that Trinamic do a 3-axis motion controller chip [www.trinamic.com], could be interesting.

In general though, for the type of control required for printing, a fast 32 bit MCU seems to be sufficient.]]> bobc Developers Sat, 30 Mar 2013 20:42:48 -0400 https://reprap.org/forum/read.php?2,195973,196198#msg-196198 https://reprap.org/forum/read.php?2,195973,196198#msg-196198 REPRAP SQUAD Developers Sat, 30 Mar 2013 12:42:15 -0400 https://reprap.org/forum/read.php?2,195973,195973#msg-195973 https://reprap.org/forum/read.php?2,195973,195973#msg-195973
[www.kickstarter.com]]]> redreprap Developers Fri, 29 Mar 2013 17:34:48 -0400