DSP/uControllers

[cherler]

I was curious what you all like using!

Listening to the Alexander, DRod, and UC podcast and thinking about spin chips. I've done some DSP work in school, we used some esoteric TI development board. I've thought about getting into it, but I'm a little hesitant.

I'm way more versed in just regular uControllers, I work in a robotics lab and we've used tons of different chips. I'm using PIC right now, just cause it's convenient for now, i.e. the chips and programmer are lying around haha. Just because I'm more familiar with uC's, I'm tempted just to throw some high quality A/D and D/A chips in the circuit and just running with that. What do you guys use/think about all this?

[drolo]

Some people seem to be using 32 bit PIC's for DSP these days, at least in the diy world. I vaguely remember reading sonic crayon mentioning that (but my memory is not reliable ...)
The fv1 was my first ever experience with programming actually and I still find it hard wrapping my head around certain concepts of the spin assembly (and DSP in general)
I have been having the urge to take some time to learn the basics of DSP, particularly audio.
Been trying to learn come C and it seems way more intuitive than the spin asm. I hope I can find some time to do all these things :-)

[cherler]

Yeah we use C for everything and it is really nice once you own it. We only did a little inline assembly in class and even that felt way more obtuse than just C, which on a chip running at 72 MHz is probably (hopefully) fast enough haha.

I kinda want to get into STM, but the support doesn't seem that great? Damn good hardware though.

[eatyourguitar]

DSpic is the hot shit the only question is if you need all the ram you can get with arm STM and external ram on the pcb. I think reverb in FV1 is more because people have done it before than because it is the ideal choice. most but not all manufacturers of microcontrollers are charging $400 to $4000 for the dev kit that gives you the optomised compiler you really need to make the chip scream. when you wan't to use free software to program a well documented architecture you can narrow it down to like %20 of everything that is available. I looked at NXP in DIP8 the specs were great but the software was expensive. same is true for analog devices black fin. If I was a big business I would do everything on black fin. this is where electro harmonix is at for %80 of the DSP based pedals. if you can buy a used monome aleph you can get started compiling with the free tool chain on a linux machine. tool chains are a pain in the ass. so much can break the installation. I think there is a ready made distro for the aleph that has it all setup already. it would be nice if we could use the free black fin toolchain to program all the black fins and not just the specific hardware that comes with the aleph.

[cherler]

Yeah PIC is perfect for me right now, no DSP just controlling stuff. I found a chip with built in zero crossing detection to solve that muting problem I posted about awhile ago. It's good to hear their 32bit stuff is actually well received for DSP.

This is the first I've heard of black fin, looks pretty sweet. There's a relatively cheap dev board on digi-key right now it looks like.
http://www.digikey.com/product-detail/e ... hgodFTMClQ

[Dr. Sherman Sticks M.D.]

black fin is also i'm pretty sure what the op1 is powered by.

[cherler]

Well that's pretty neat, maybe this is worth getting into.

[cloudscapes]

just different ways of doing stuff.

blackfins etc are good for simulating the physics of reverbs/delays when you're REALLY trying to nail a sound. like you want the natural resonance of the metal chassis of the tape delay to be calculated/simulated. crazy advanced stuff like that, blackfins are good at that, but the learning curve is huge.

but you can do reverb/delay just fine with general purpose microcontrollers. you just have to forget the physics stuff and just let the inherent sound of your circuit define your sound.

I used pi32's to make a mid/hi-fi delay.

[cherler]

Yeah I'm not into the physics type stuff at all. I'd rather just fuck around with an idea till a sound I happen to like pops out. Maybe I'll just stick to PICs. I'm assuming pi32 is pic32?

[cloudscapes]

yeah sorry I meant pic32. can do a lot with it. even though it's not a dedicated DSP, done bitcrushers/samplerate reducers, waveshapers, ugly digital distortions, delays, loopers, ringmods, pseudo pitch shifting. I'm sure I could do some kind of reverb too if I actually tried.

[cherler]

Yeah that's pretty convincing haha, I'm gonna stick with pic for a while. Thanks!

[multi_s]

this is only my 2 cents, but from someone that used to use microchips devices a lot i would look into something else when you go to the higher end. their 8 and 16 bit devices are decent enogh but the pic32 based on MIPS is really lacking compared to other 32 bit devices on the market right now. Also you have to pay for code optimization with micorchip where as the compilers are free and optimization also free with several other manufacturers.

as a test look up the length of a pic32 flavor errata sheet adn then loop up an stm32 errata sheet. this will be enlightening.

also i think you can find a recent open letter on microchips website where they state thet since acquiring atmel they have major issues meeting the fab demand for atmels designs but no problem meeting the demand for microchips devices. ie people don't want them, they want atmel designs.

[cherler]

Yeah I took a look at that and I definitely see your point. I've found a few resources for getting started on stm32, how did you get going on it?And thanks for the input!

[Strange Tales]

What resources you got for starting with stm?

I've got a few ideas I'd like to implement.

[cherler]

I haven't had the time to dig through these yet, I just found them after a little googling, so no promises anything here is good or what I think it is...

Seems a little dense but has info on a bunch of different available toolchains
http://www.st.com/content/ccc/resource/technical/document/user_manual/group0/d0/f7/45/d7/3b/96/47/b3/DM00285842/files/DM00285842.pdf/jcr:content/translations/en.DM00285842.pdf

A little more step by step less breadth
http://electronut.in/stm32-start/

Another more step by step kind of deal
http://jeelabs.org/2016/12/getting-started-with-stm32/

I'm not super confident in this stuff but it seems like a good place to start, maybe at least find out more about what I need to find out more about.