GR252 and the New Raptor Series of Drives

We are in the design phase of a new drive that will be a follow up to our most popular drives ever, the G250X and the G251X. We are designing around an ice5 FPGA and a new ultra-efficient MOSFET and gate driver pair that will let the drive run up to 50VDC and 7A, doubling the power of the current G250X and G251X. These new components are so efficient that the drive won’t need heatsinking at any current. Right now the features we will be including are:

12 - 50VDC and 100mA - 7A continuous operating power (10V dropout)
14 selectable resolutions, from half step to 256 microstep
Small size: 1” x 2” board size, or roughly the same surface area as the G251X
Split 3.5mm connectors in a similar setup as the G214 connectors
An onboard DIP switch for current and resolution setting
Razor thin: The MOSFETs on the bottom are only 1mm thick, meaning the drive will be ~1/2” thick in total

After we have these initial requirements laid out on the board we can add features that will fit. Our interest in this is twofold: to out-engineer the competition and to out-price the competition. The GR252 will be the first in our Raptor Series, quickly followed up by the GR214 with cool-running MOSFETs and performance improvements. Following those releases we plan on creating a family of drives, such as a header based variant that is meant to be plugged into a larger motherboard like the G250X currently does.

And now for the kicker: The price of this drive will be low. Like super low. We are shooting for a $30 price in OEM quantity and a single-unit price of under $60. The drive will still come with our free technical support, free 3-year warranty, and will be manufactured in California like the rest of our products. In order to get these out in the field as quickly as possible we plan on selling the first 250 of them for $15, with a limit of two per customer.

I will be giving design updates on here as this thing moves along. This will be a whirlwind of a design, and we are hoping to move on to prototyping and beta testing quickly.

We want to know what you need in a step motor drive. While we are in the design phase we can incorporate as many customer requested features as possible, so let us know what you want to see.

Stall detection and fault outputs, so if a motor stalls you can have the fault signal shut down the system.

Configurable current reduction.

I’ve been playing around with some of the trinamic driver chips and the one nice feature is the very quiet stepper motor operation. This happens only at low current and rpm speed though. For a lot of belt driven applications (3D printer), this works rather well. However I’ve already destroyed 2 of them while testing. Of the dozen or so geckodrivers that I use, never run into that problem.

Other wards a very low noise mode would be useful for me with the reliably and anti-resonance that geckodrives are known for.

What would be ideal for an adjustable current reduction? We have two paths we could go down: Either a DIP switch option that allows two choices of current reduction (i.e. SW1 ON = 100% current, SW1 OFF = 70% current), or use a trimpot. Part of the problem with a trimpot is just how big they are; we have smaller trimpots on our G251X and G250X that would work but they are a bit of a pain to adjust but still doable. This is really a one time adjustment so the small trimpot being used wouldn't be the end of the world.

Stall detection would work at high speed only because of how easy it is to detect waveform changes. Low speed stall detect would not be sensorless and we would be quickly running into space constraints and lack of available pins for an encoder. Right now, with a FAULT OUT we would have the following pinout for the low current section:

COMMON
STEP
DIRECTION
DISABLE
FAULT OUT
+12V OPTIONAL INPUT

The +12V optional input is one of our neat features we have been spitballing around with here. This would take the 12V regulator out of the picture and allow the 12V bus the option to be driven externally, meaning you can run the drive right down to +12VDC for the power supply input. This is useful for battery-driven applications and small motors that overheat easily, and would have a 10VDC dropout voltage.

jfong,

The reason the Trinamic chips are running quietly is likely due to a high microstep resolution; the GR252 will go up to 256 microstep so it will run very quietly at low speed. We will be doing a decent number of comparisons while this is in design and it should be as quiet as any other high resolution driver. The resolutions we are going to feature will be half step, 5uStep, 8uStep, 10uStep, 16uStep, 25uStep, 32uStep, 50uStep, 64uStep, 125uStep, 128uStep, 250uStep, and 256uStep. The coarser resolutions will be upscaled to a higher resolution on the waveform, meaning they will run smoother than they are set to while retaining the same resolution as far as your pulse source is concerned.

We also have a rough idea for the new logo for these new drives. What do you guys think?

Attachment 386260

The Leadshines I'm using have software configurable current reduction, which allows you to set it to any amount.

Having the drives be configured via software would be nice, but you'd probably need to add a serial or USB port?? And of course, write the software. :)

Yes, higher speed stall detection is fine? I think the Leadshines say above 300 rpm.

Quote:

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Originally Posted by CoAMarcus

jfong,

The reason the Trinamic chips are running quietly is likely due to a high microstep resolution; the GR252 will go up to 256 microstep so it will run very quietly at low speed. We will be doing a decent number of comparisons while this is in design and it should be as quiet as any other high resolution driver. The resolutions we are going to feature will be half step, 5uStep, 8uStep, 10uStep, 16uStep, 25uStep, 32uStep, 50uStep, 64uStep, 125uStep, 128uStep, 250uStep, and 256uStep. The coarser resolutions will be upscaled to a higher resolution on the waveform, meaning they will run smoother than they are set to while retaining the same resolution as far as your pulse source is concerned.

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I figured it has to do with the high microstep and maybe some other tech that is way over my head.

I do have some Parker E-DC stepper drivers that are configurable to something like 50800 microsteps. However I never really notice that much noise reduction when running them at 256 microstepping. At least nothing as quiet as the trinamics with the same stepper motor. Anyway looking forward to testing out the new drive. Thanks!!!

Quote:

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Originally Posted by ger21

The Leadshines I'm using have software configurable current reduction, which allows you to set it to any amount.

Having the drives be configured via software would be nice, but you'd probably need to add a serial or USB port?? And of course, write the software. :)

Yes, higher speed stall detection is fine? I think the Leadshines say above 300 rpm.

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So our drives currently have high speed stall detection but we don't advertise it because it only works above certain speeds and is about 75% accurate. This one will be designed with the intention of that being a feature.

Regarding standby current; we can do a programmable current set through an SPI interface but it would get to be a little higher-order than the drive is designed for. Our GM215 has user settable current through software and works just fine with that down to 10mA increments. The GR252 is meant to be as plug-and-play as possible initially but we could potentially do that with a later revision or version.

The trimpots that we stuff in our G251X and G250X come pre-set to the 12 o'clock position, which would make the default current reduction 50% on the drive. This is not a bad number and the user would not have to touch the trimpot at all if they did not want to. If they had a Z axis with a large weight on it they could turn that up to 100%, or if they have a battery driven application they could turn it down to 0%. I'm liking this idea a lot. Thanks!

Quote:

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Originally Posted by CoAMarcus

So our drives currently have high speed stall detection but we don't advertise it because it only works above certain speeds and is about 75% accurate. This one will be designed with the intention of that being a feature.

Regarding standby current; we can do a programmable current set through an SPI interface but it would get to be a little higher-order than the drive is designed for. Our GM215 has user settable current through software and works just fine with that down to 10mA increments. The GR252 is meant to be as plug-and-play as possible initially but we could potentially do that with a later revision or version.

The trimpots that we stuff in our G251X and G250X come pre-set to the 12 o'clock position, which would make the default current reduction 50% on the drive. This is not a bad number and the user would not have to touch the trimpot at all if they did not want to. If they had a Z axis with a large weight on it they could turn that up to 100%, or if they have a battery driven application they could turn it down to 0%. I'm liking this idea a lot. Thanks!

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Oh, I was thinking for the GR214

Sent from my SM-G955U using Tapatalk

ger21,

Gotcha. The G214 already has an adjustable standby current through its T2 trimpot, and the GR214 will retain that feature.

The GR252 project is coming together pretty quickly and we are already discussing the GR540, which will be an update to the G540 that features this drive as the heart of it. I may make a separate thread for it when we begin its design in earnest but right now I am curious what people would want to see in it as far as features are concerned. We are thinking of 8 inputs and 8 outputs (or 16 and 16) to allow more options for machine setup, and also having a six axis version called the GR560. What does everyone want on their multiaxis controls these days? Maybe a true torch height controller option built in? Or would that just limit it for non-plasma users?

For the GR540 I would love to see a Serial/USB based management, debug, stats and firmware update capability. This would make deploying hundreds of GR540/GR560 really simple as I could just apply a list of parameters. Currently, with the MX4660's, I have to go tweak all the switches.

For the high speed time line; get the GR540 out the door with Serial/USB firmware update capability, add management, debug, stats at a later date. Don't get bogged down with software. All I am after is a basic command line.

We want to know what you need in a step motor drive chasebank atm near me

While we are in the design phase we can incorporate as many customer requested features as possible, so let us know what you want to see.