A faster ARM controller

As RAMPS-FD v2 is nearing tape out, I have been wondering if we can take advantage of some of the faster ARM cores around, and get some more bang for the buck.

Of particular interest are the Cortex-M4 with hardware FPU, and other DSP like features. The two I have been looking at closely based on availability and cost are STM32F4xx and LPC43xx.

The STM32F407VET6 has an M4F core at 168MHz, 1MB Flash 192KB RAM, USB in a 100 pin LQFP package, about $11 one off. There is a also a dev board for $15, the STM32F4Discovery. For an extra $2 there is an ethernet variant.

So that would be a pretty fast chip compared to the Due.

NXP have something even more interesting, a dual core chip with a Cortex M4F and a Cortex M0. Both clock at 204Mhz. The LPC4333JBD is 144 LQFP also about $11.

The dual core architecture allows the M0 to be dedicated to driving the steppers and doing acceleration profiles, while the M4 handles the user interface and number crunching. We could use separate M4F and M0/3, but having them in one die means they can share memory and avoids the need for high speed comms interface, and one package is easier to deal with physically.

Another advantage of these chips is that some of them have an external memory interface, which allows several MB of RAM to be attached. This would allow some very long lookahead buffers.

Overall, I think the LPC4300 series is the best available at the price point and the most interesting at the moment. Freescale also have some good value chips in the M4/M0 range.

From the software point of view, NXP, Freescale and STM all seem to be throwing their hat into the mbed arena. If anyone hasn't used mbed, it's like a much better version of Arduino.

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Q: Are you looking at an 'all-in-one' board version of RAMP-FD -basically adding the CPU on the board itself?

If so, I'm interested in this as well. In fact, that was sort of my reason of getting involved with your RAMPS-FD project in the first place.

I was thinking of a base board to replace the Due, and reuse the RAMPS-FD, or RADDS, or perhaps Decapede?

Although the modular approach requires some compromises, having to respin the stepper drivers, mosfets, thermistor is time consuming, and it allows to concentrate on just the CPU board. I also figure the field is quite well served with all in one ARM boards, R2C2, Smoothieboards, 4pi, Duet.

However, I have an open mind at this stage, especially if collaboration is involved to share workload, my timescale is "2014" so it's quite relaxed

I also noticed today while I should have been working, that Freescale have "Vybrid" VF3 series, which has Cortex A5 266MHz, double precision FPU, 1.5MB on board RAM, in a 176 LQFP, I think it requires external Flash. Farnell have them listed at £11 singles.

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Well, there is no reason we can't create a base board (especially if at the time we can somehow address the USB ground loop issue that it seems almost all Arduino variants seem to suffer from with an external PS in use), and then later look at turning it into an "all in one" design as a "next generation" thing.

With the Beagle Bone Black costing a mere $45 for a Cortex A8 1Ghz, 512MB RAM, etc does it even make sense to try to make something to compete with that? The BBB is actually cheaper than an official Arduino Due, although there are Due clones in the $30 region.

I don't know if Replicape is shipping yet, but it seems to have been a long time in development. In theory it should be relatively easy to adapt RAMPS-FD for the Beagle Bone. The official guidance for cape developers is a bit more complicated, I haven't digested all of it, but there are probably some things that are not strictly necessary.

However, with a ATmega2560 costing around $10, there are more cost effective chips. If Chinese shops can sell an Arduino Mega2560 clone for little more than $15, then in theory they could sell a board with an LPC4333 for a similar price. This would still be a better low cost alternative.

I'm still liking the LPC4333. Even if we just used the M4 part, it would be pretty good.

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I found a dev board for the LPC4337 on ebay which is similar to the LPC4333 but with with more Flash [www.ebay.co.uk]. I've ordered one to play with, the price is about $40 which gives an idea of much a base board could cost.

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Why not back parts supported by libopencm3? It makes for a decent HAL for Cortex M3/M4/M0 parts from ST, TI, NXP, and Atmel. It's rough around the edges, especially in support for non-STM32 parts, but unlike Arduino or mbed it's easy to contribute patches.

I think that the short board now is printer firmware . The popular 3D printer firmwares do not support 32bit MCU well .Now only repetier and aprinter support normal coordinate , delta coordinate and coreXY coordinate and 32bit MCU . For delta coordinate ,firmwre need interpolation, so 32bit MCU is so hunger ,and I am working hard on it.

can People can develop firmware for ardino due and DUET on arduino IDE which has a user friendly GUI and lots of lots of lots libs.... Base on that reasons ,I think Atmel SAM3X is an option ...

Edited 1 time(s). Last edit at 01/30/2014 03:30AM by sakunamary.