LeafLabs Garden » Topic: Interesting dual-core ARM Cortex M4+M0 from NXP

LeafLabs Garden » Topic: Interesting dual-core ARM Cortex M4+M0 from NXP http://forums.leaflabs.com/topic.php?id=1065 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:18:07 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://forums.leaflabs.com/search.php gbulmer on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065&page=2#post-6677 Thu, 29 Sep 2011 17:02:53 +0000 gbulmer 6677@http://forums.leaflabs.com/ <blockquote>.. i would like it to have MIDI/OSC capability .. </blockquote> Do you mean you want USB and/or Ethernet? Or are you only describing some of the software you would like? <blockquote> ... i suspect i'm leaning more in Christian's direction audio quality-wise.</blockquote> I think that I am aiming for something at least as good as the MICrODEC and likely better. Minimum spec is CD quality, i.e. 44.1Ksps at 16bit, 48Ksps at 24bit, and more likely 96Ksps at 24bit. <blockquote>as for the Raspberry Pi, i strongly believe their heart is in the right place ...</blockquote> Yes, they seem to have a great attitude and are making progress at a terrific rate. I haven't been able to find the hardware specs. for GPIO, I2S, SPI and I2C yet, though. Some of the subsystem specs will never be available because the subsystems embody commercial secrets. Shame, I'd like to experiment with some of that hardware :-) metaphysician on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065&page=2#post-6657 Wed, 28 Sep 2011 12:33:56 +0000 metaphysician 6657@http://forums.leaflabs.com/ You're the moderator - so i'd guess unless i start a new topic out i probably can't rename Christian's topic... anyway, more to the point - whatever card or device that could be built along these lines i would like it to have MIDI/OSC capability to control most parameters as well as to have physical knobs or sliders. my MaxMSP setup comes with four fairly complex LFOs that can modify almost any parameter and i really like using it especially to get discontinuous fast changes in parameters. at that point the trick is modelling the control apparatus on a portable device like a tablet, while letting the card do the heavier lifting DSP-wise. at any rate your learning platform is interesting, as i am also a relative newbie, though i suspect i'm leaning more in Christian's direction audio quality-wise. as for the Raspberry Pi, i strongly believe their heart is in the right place, as they are a non-profit. they are really motivated to bring programming and electronics skills back to schools. in general, they've been pretty responsive to user inquiries, and i believe their answer on open sourcing was a wait and see thing. their concern was hobbyist builders not being able to order certain chips in small enough quantity to build the boards. Eben Upton one of the main guys has said in the past he'd love to have the Chinese copy his design and flood the market with clones. it sounds to me that you should perhaps inquire on their website, as it seems to me that you have similar aims, goal wise. i did buy an R4 Maple but it was borrowed by a friend who eventually bought an R5 for me to replace it and then borrowed that again, so i'm thinking for payback i might want to wait for a RaspberryPi instead. 700MHz is a pretty hefty bunch of cycles for DSP... scott gbulmer on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065&page=2#post-6651 Wed, 28 Sep 2011 09:28:35 +0000 gbulmer 6651@http://forums.leaflabs.com/ scott - thank you very much for the links and ideas. That is very helpful to me. I am impressed by the RaspberryPi (I actually touched one at the weekend :-) I think it is a very exciting piece of technology, but I am told there are concerns about how open it actually will be. I really don't know enough of the detail, so I apologise to all involved if I am mistaken. My focus is a platform to learn about programming, and some science, technology, engineering and maths (STEM), along the way. I run workshops for school children and adults to learn to program using microcontrollers. I believe that stripping the platform down to barest essentials helps people understand what is actually happening. So having an operating system around can obscure the visceral experience. Audio is interesting because humans have pretty good sensors, and processing of real-time 'events'. We also like music :-) So my goal is to help people understand programming through audio experiments (and a bunch of other experiments). Edit+Edit: Christian - Maybe we should rename this thread to something like "Interesting Cortex-M4 chips, especially for audio"? metaphysician on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065&page=2#post-6648 Tue, 27 Sep 2011 21:37:27 +0000 metaphysician 6648@http://forums.leaflabs.com/ I for one would be extremely interested in a higher power version of something like the MICrODEC. as the hardware gets reduced in size i become more and more interested in seeing if one could model my MaxMSP patch DSP functionality (which is basically a modular 5 voice sampler with a total of 75 stereo seconds of sampling or live processing split between 5 sample slots with resampling, LP filter, ringmod, delay and reverb) in a portable DSP device of some kind. i find myself casting looks at something like the Raspberry Pi which apparently is supposed to have an I2S port on its GPIO pins. would that give you the muscle and/or memory you'd need for the job, or am i not seeing limitations that a dual core ARM4 would be better at solving? possible interesting side projects to stir the pot - one high power one low: High power - BeepCat from Chris Randall of Audio Damage - makers of plugins. Check his proposal out. It's definitely on the higher end price-wise and based around a Beagle Board which i believe isn't included in the price. He mentions the Meeblip as an inspiration (another low power monophonic Atmel based DIY offering in the Mutable Instruments-Shruthi mode). <a href="http://www.analogindustries.com/blog/entry.php?blogid=1316213971302" rel="nofollow">http://www.analogindustries.com/blog/entry.php?blogid=1316213971302</a> Low Power - WTPA 8 bit sampler version 2.0 <a href="http://www.narrat1ve.com/forum/comments.php?DiscussionID=222&page=wtpa2-teaser" rel="nofollow">http://www.narrat1ve.com/forum/comments.php?DiscussionID=222&page=wtpa2-teaser</a> there's a lot of posts on this and the firmware is still in flux so it hasn't been released, but hopefully gives you a taste. whatever else happens i'd be very interested in what either of you two has in mind for an audio processing board. are there separate links or information for either of your ideas in this regard? best to all, scott gbulmer on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6639 Tue, 27 Sep 2011 11:57:58 +0000 gbulmer 6639@http://forums.leaflabs.com/ <blockquote>If I understand correctly, your use case is more aimed towards offering audio in addition to other aspects - blinking lights, robot control, etc - as a general teaching & experimentation platform? </blockquote> I apologise, I guess I am not expressing myself clearly. It is intended to be part of a general teaching & experimentation platform. It does not need all the facilities for all the experiments. A goal is to have high enough audio quality on this module so that users can do many of the obvious fun and interesting audio experiments, and more, but it is not an 'application specific' solution, so it won't have all of the controls that, for example MICrODEC has. It is intended to be extensible, so it should be able to blink LEDs, maybe control motors etc. for a robot. Yes, we are balancing different sets of requirements and tradeoffs. cbrunschen on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6636 Tue, 27 Sep 2011 09:17:54 +0000 cbrunschen 6636@http://forums.leaflabs.com/ If I understand correctly, your use case is more aimed towards offering audio in addition to other aspects - blinking lights, robot control, etc - as a general teaching & experimentation platform? That's quite different indeed from what I had in mind, so it's not surprising you'd prefer a different set of tradeoffs: Since my thoughts were more in the direction of a platform specifically for _audio_ generation & processing, and experimentation and playing with _those_, having a more predefined set of user controls (pots & encoders) would make more sense, even though for your use that would be too restrictive and at the same time adding needless complexity. Best wishes, // Christian Brunschen gbulmer on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6634 Tue, 27 Sep 2011 05:52:12 +0000 gbulmer 6634@http://forums.leaflabs.com/ <blockquote>If I read the datasheet correctly, the STM32F4 has an FSMC (Flexible Static Memory Controller) that allows connection of 4 banks of 128 MB (26 address lines, 16 bit wide memory bus => 128 MB) each of static memory (SRAM, Flash, or similar). The LPC4300 has an EMC (External Memory Controller) that allows connection of 4 banks of memory including SDRAM, 2 of which can hold 256 MB each, giving a much less expensive way to connect a lot more memory. </blockquote> I agree with your analysis. As I said, my use cases are different. Ideally I'd like to have the simplest board possible. That might mean no external memory, use a 64-pin part, and enable the kids to use the same board to make a robot or a music gizmo, or blink LEDs like KITT in Knight Rider. Minimise extras. <blockquote>If you want something simple, then I'm not sure you need something that has more than 2 inputs. Either way, both the STM32F4 and the LPC4300 have 2 I2S interfaces so you can easily go up to 4 inputs and outputs on each. </blockquote> I mean simplicity of hardware, not simplicity of concept or purpose. I don't need to do much to the ADC inputs other than make them accessible. I can make a board which carries a microphone, or small amplifier, or socket, and filter which the users can plug in. Similarly with output. If a kid (or adult) wants to try and sing a duet with a bat, and has a go at building it, I will be utterly thrilled. <blockquote>What do you mean by 'minimise fixed user interface'? If you expect there to be some set of inputs such as rotary encoders and/or potentiometers, ... </blockquote> I don't want to have anything more than gain-control on the analogue side. Ideally everything else is for the user to choose. A key goal is to provide an educational experience for people who have never programmed, or have done very little programming. A goal is to give them a something which provides the fewest constraints, and allows them to explore and discover. It is not a goal to give them a perfect audio solution out of the box. <blockquote>... (by the way, you're missing a 'C' at the end of 'MICrODEC ... </blockquote> Thank you. Sorry. <blockquote>You mention that your current design is simpler than the MICrODEC ... would you care to elucidate? </blockquote> May I delay that? We need to agree stuff, which may later change. I will say, take a *near minimal* usable stereo analogue audio chain (buffer, low-pass filters, gain controls), with normal audio-quality ADC/DAC, with an STM32F103, and accessible pins, and you are mostly there. An issue is external RAM. I am not currently intending to have more RAM than Native. Even that seems like too much of a luxury :-) Another issue is how ready-to-go is it. I like the "ready to go" argument to give a great 'out-of-the-box-experience'. I also like the minimalist "let them choose as much as possible" argument. My 'druthers' is as little as possible that will 'do audio' out of the box. I think that is plenty for a person to learn with, and has lots of potential. I am only one voice. We have a proposed process which generates evidence, so I am much happier getting some evidence than using 'gut'. If we discover it is too hard for our users to build a physical UI, then we can change. If we discover that building the physical UI is very interesting to some learners, and maybe they would like even more options, then that needs to be taken forward. Okay? (full disclosure: I am not a member of LeafLabs staff.) cbrunschen on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6631 Tue, 27 Sep 2011 02:18:05 +0000 cbrunschen 6631@http://forums.leaflabs.com/ If I read the datasheet correctly, the STM32F4 has an FSMC (Flexible Static Memory Controller) that allows connection of 4 banks of 128 MB (26 address lines, 16 bit wide memory bus => 128 MB) each of static memory (SRAM, Flash, or similar). The LPC4300 has an EMC (External Memory Controller) that allows connection of 4 banks of memory including SDRAM, 2 of which can hold 256 MB each, giving a much less expensive way to connect a lot more memory. The SPI Flash Interface also allows connection of supposedly-less-expensive serial Flash chips (instead of parallel ones). If you want something simple, then I'm not sure you need something that has more than 2 inputs. Either way, both the STM32F4 and the LPC4300 have 2 I2S interfaces so you can easily go up to 4 inputs and outputs on each. What do you mean by 'minimise fixed user interface'? If you expect there to be some set of inputs such as rotary encoders and/or potentiometers, I actually think that it's an easier model to handle for experimentation if the values from any available user interactions 'automagically' appear in variables that the program can simply use without having to factor in any particular delay in acquisition; so having the reading of values from encoders / potentiometers handled by a secondary processor - which the user never actually has to programs themselves! - actually would make things conceptually easier. You mention that your current design is simpler than the MICrODEC one (by the way, you're missing a 'C' at the end of 'MICrODEC') – would you care to elucidate? Best wishes, // Christian Brunschen gbulmer on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6626 Mon, 26 Sep 2011 20:36:38 +0000 gbulmer 6626@http://forums.leaflabs.com/ cbrunschen - my current STM32F103 design is simpler than the MICrODE. I am aiming for something with a 'softer' user interface because part of the goal is to enable children to create that too. I like Wolfson on I2S; as well as the WM8731, I've been looking at some slightly higher capability parts. I am aiming for something more flexible than the MICrODE. So, while the quality for the high-quality audio channels will be comparable, I am not aiming at a specialised use. Hence I think having upto 16 more input channels, and stereo DAC output as well as PWM output, to supplement the discrete audio CODEC seems much more fun to me. I agree with much of what you say about the second processor. But my target audience and some use cases are likely different. I prefer to minimise the amount of fixed user interface, so the Cortex-M0 would be less valuable. After all, human interaction is soft real-time, and rarely happens in under 10ms, and the audio I/O can use DMA. Plus, it is aimed at education, so having understandable problems is "a good thing". <blockquote>The main thing that makes me look at the LPC4300 over the STM32F4 </blockquote> They both have SDIO, both 16-bit external memory, so I are you referring to the "Quad SPI Flash Interface"? cbrunschen on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6610 Mon, 26 Sep 2011 06:51:19 +0000 cbrunschen 6610@http://forums.leaflabs.com/ I'd actually completely ignore the built-in ADC & DACs on the devices, because they're not really aimed at audio applications on either the STM23F4 or on the LPC4300; I'd use a dedicated stereo Codec, like the Wolfson WM8731 as is used on the OpenMusicLabs projects (see <a href="http://www.wolfsonmicro.com/products/codecs/WM8731/" rel="nofollow">http://www.wolfsonmicro.com/products/codecs/WM8731/</a> ), which also has a headphone driver. The LPC4300 and the STM32F4 both have I2S interfaces, which are specifically for digital audio I/O and which can be used with the WM8731 and its friends, so that makes things nice and straightforward - and equally so in both cases. The main thing that makes me look at the LPC4300 over the STM32F4 is the ease of connecting lots of memory, actually - both for storing pre-generated-or-recorded waveforms (in Flash) and for offering lots of space for delay lines or similar. But having a separate I/O processor would make it possible to have an environment where there was simply no question of I/O interfering with the audio generation and/or processing, especially if that I/O involved user interaction; even without using an LCD or similar, the I/O processor could handle any and all encoders, potentiometers, etc - interrupts, ADC, and all. In fact, imagine a simplified exploration environment, similar to the Arduino / Maple environment, where instead of a 'loop' function, you could simply write a 'generateNextSample' and a 'processSample' function perhaps, which would execute on the main processor, and would be called from the 'framework' code at suitable audio resolution – something similar to how the OpenMusicLabs AudioCodecShield does it when connected to an Arduino or Maple, perhaps. At the same time, the software on the I/O processor would be fixed and always remain the same, and simply write the values it read/processed from encoders, potentiometers, buttons and whatnot, into predefined well-known memory locations that could be exposed through well-documented variables or functions, since on the LPC4300, the main (M4) and I/O (M0) processors share the same memory and peripherals. This gives us the advantage that the main audio processor would never have to wait for an ADC conversion to finish, or have to handle interrupts when the decoder changes or a button is pressed, or similar, and instead focus entirely on the generation and processing of audio data in the presence of whatever values have already been processed bu the I/O processor. gbulmer on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6608 Mon, 26 Sep 2011 05:06:15 +0000 gbulmer 6608@http://forums.leaflabs.com/ cbrunschen - <blockquote> With something based on a more powerful chip ..., you could have a single box that does both jobs - and with enough power that you can use a simpler programming language & programming model than having to squeeze performance out of every cycle. </blockquote> Yes, that is exactly my approach. It is Soooo much easier to get something working when there is plenty of spare 'headroom'. <blockquote>The LCP43xx simply seem like they offer both a nice amount of power, including suitable DSP-like instructions for generating & processing audio, as well as allowing access to nice amounts of memory. </blockquote> Yes, that Cortex-M4 CPU is very similar to the Cortex-M4 in STM32F4xx (I haven't looked at the details of how LPC43xx caches flash memory so I can't say they are identical). The STM32F4xx ADC & DAC peripherals appear to be significantly faster, and STM32F4 has stereo DACs when compared to LPC43xx. So in that area, the STM32F4 part appears to be a better choice for audio applications. <blockquote>As an added bonus, they offer connectivity (USART, USB, Ethernet even), a possibility for a bit more of a UI (an LCD interface is included on some of the chips), ...</blockquote> The STM32F4 and LPC43xx seem to be comparable there. <blockquote>... and the secondary processor (the Cortex-M0 one) could be used to offload I/O, user interaction, etc, while letting the main processor focus on the audio generation & processing.</blockquote> So this is the key benefit for you? It sounds like a great idea, but I am very concerned that it will be hard to use, especially for new programmers. Have you any plans on how you'd make it easy enough for folks too use? Thank you for the pointers to Open Music Labs and Mutable. I'll have a dig around and get in touch. cbrunschen on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6605 Mon, 26 Sep 2011 03:21:35 +0000 cbrunschen 6605@http://forums.leaflabs.com/ My thoughts are really rather loosely plucked out of the air from looking at the MICrODEC (<a href="http://www.openmusiclabs.com/projects/microdec/" rel="nofollow">http://www.openmusiclabs.com/projects/microdec/</a>) and the Shruthi-1 (<a href="http://mutable-instruments.net/shruthi1)" rel="nofollow">http://mutable-instruments.net/shruthi1)</a>; both use microcontrollers, the Shruthi-1 to generate sound, the MICrODEC to process and filter it. With something based on a more powerful chip that also allows a fair chunk of memory, both persistent for things like waveforms to generate and transient for things like delay lins while processing the audio, you could have a single box that does both jobs - and with enough power that you can use a simpler programming language & programming model than having to squeeze performance out of every cycle. The LCP43xx simply seem like they offer both a nice amount of power, including suitable DSP-like instructions for generating & processing audio, as well as allowing access to nice amounts of memory. As an added bonus, they offer connectivity (USART, USB, Ethernet even), a possibility for a bit more of a UI (an LCD interface is included on some of the chips), and the secondary processor (the Cortex-M0 one) could be used to offload I/O, user interaction, etc, while letting the main processor focus on the audio generation & processing. I'd think the Open Music Labs people and the Mutable Instruments people would be good to talk to about anything microcontroller-audio-related. Best wishes, // Christian Brunschen gbulmer on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6591 Sun, 25 Sep 2011 15:09:38 +0000 gbulmer 6591@http://forums.leaflabs.com/ Chrsitian - I've been working on a sound card which may or may not get to production. My ultimate specification sounds similar to yours. I am happy to use STM32F1 as an initial step. I agree hardware floating point may make it much easier for people to program it without having to resort to fixed point, or more complicated tricks. But an STM32F1 is quite a lot of processing power. As I wrote I am most interested in providing a platform that both children and adults could program to create their own 'sound machinery'. Having watched some of the NXP videos, I am genuinely worried that it will be significantly harder to use than a STM32F4. I believe some of the work can be offloaded from the processor to DMA controllers. What sort of things do you think would benefit from the Cortex-M0, user interface? Are there any groups or people you'd recommend I should read or contact? poslathian on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6590 Sun, 25 Sep 2011 14:52:38 +0000 poslathian 6590@http://forums.leaflabs.com/ Sorry everyone! Marti merely propagated a lie/honest error I was floating around the office. I got confused for a moment and back of the enveloped the 8Mb Ram as allowing for 90Sec of 16bit 44KHz audio. Obviously I was off by a factor of 8. The actual value is 11.3 seconds. However, with the SD card, you could stash arbitrary stuff. The real question is whether or not you can read/write from the SD card and produce/capture audio at the same time. Using SPI and SDFat, the answer is "no" but just barely. Using SDIO (which doesnt have lib support) I bet it would just work. Use the DMA you are probably golden. You may have to clear flash pages in advance though, depending on what the wait is there. I suppose you could asynchronously clear flash pages, while writing to already cleared ones. I have been really wanting a more capable loop pedal, for storing several tracks simultaneously and providing a better interface to do so. A sampler would also be cool. cbrunschen on "Interesting dual-core ARM Cortex M4+M0 from NXP" http://forums.leaflabs.com/topic.php?id=1065#post-6580 Sun, 25 Sep 2011 04:05:37 +0000 cbrunschen 6580@http://forums.leaflabs.com/ Oh, I'm not saying that this chip would suit the Maple-or-similar target market, or that Leaflabs should switch. My thought is more something along the lines of the open music labs <a href="http://www.openmusiclabs.com/projects/microdec/">MICrODEC</a> or the Mutable Instruments <a href="http://mutable-instruments.net/shruthi1">Shruthi-1</a> - a programmable / hackable sound generation and processing platform, mostly self-contained; but with enough persistent memory (Flash) to be able to store a fair chunk of sampled waveforms for generating audio, enough RAM for delay lines and other storage for audio processing, enough processing power to be able to be able to both generate sound and process it while being programmable without having to resort to squeeze-performance-out-of-every-cycle tricks, and a nice set of connectivity (USB, MIDI, possibly even ethernet) to boot. I am of course making noises on the open music labs forum as well. I just thought I'd mention this chip here because of its rather interesting asymmetric dual-core approach (and put it into a context that sprang to my mind). Best wishes, // Christian Brunschen