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Is MbSID STM_32 planned ?


Kyo
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Hi,

I wonder if Midibox SID will benefit from STM_32 core in a future version.

Underlying question is:

What is the best choice ? Build a MB-6582 or build a modular SID V2 so that new cores can be plugged in when this new version would arise ?

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Well, I think I should let TK speak for himself (I rarely take part on any conversation in here anyway so who am I to reply?), but according to this post there will be another version at some point: http://www.midibox.org/forum/index.php/topic,12673.msg106686.html#msg106686

However TK probably wants to say something about this as well  :)

That said something I can speak about: I decided to go for MB-6582. My original intention was to make a version of my own with some modifications, but the ready made PCB is just priced fair enough so I thought to save my precious time for another time and go with a known good design. Plus it's alot less hassle compared to building the thing from a separate modules - again saves my precious time.

However I'm still thinking about implementing part of the mods I've had in my mind (to try them out if they make any sense). When/if there will be MBSID V3, I will start from scratch and re-make the synth with the new design. I'm actually all thrilled about the STM32 core (wonder if I could collaborate somehow).

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I guess the question is, what would 32-bit do for SID?

The obvious:

  • Faster
  • C programming is easier (what else would you add? More sequencers?)
  • "unlimited" memory using external cards


    The negative:

    • Can't use CAN buss and USB simultaneously, so any multi SID setup couldn't be controlled over USB etc.


      It's a tricky one. Does the PIC SID V2/MB-6582 do enough for you? If so, go for it!
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What about letting one Core control more than 2 SIDs?

Wouldn't be surprised if one Core could handle all the SIDs. These beasts are quite different type of league... Btw, here's another post by TK that popped on my mind: http://www.midibox.org/forum/index.php/topic,12632.msg106231.html#msg106231

I don't know if 32-bits give any unconditional advantage over PIC (MBSID is just great thing already!), so it's also something up to the end user to decide. But sure it gives alot of freedom for new features (although the original HW design may be also limiting this but dunno, the STM32 does not have external bus anyway). I think the biggest down sides in 32-bit designs are the fine-pitch SMD cases and somewhat more complicated development tools. But nothing that one couldn't survive!

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MB-SID V3 is still a long way in the future... I won't even hypothesize about actual hardware design... some people might recall that MB-SID V2 was going to use PIC18F4620 and require two IIC_MIDI modules, which is how I designed the original MB-6582 "prototype"... and then that got superseded by PIC18F4685 and CAN bus master/slave comms. Luckily TK didn't change his mind on how stereo SID pairs would be controlled by one PIC. :)

However, I am fairly confident that there will be an "upgrade path" for MB-6582, so people can upgrade their MB-6582 to MB-SID V3 firmware running on (I assume) an STM32... i.e. using a Core32 "module" as an expansion board. It seems very unlikely that such a thing won't be possible.

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However, I am fairly confident that there will be an "upgrade path" for MB-6582, so people can upgrade their MB-6582 to MB-SID V3 firmware running on (I assume) an STM32... i.e. using a Core32 "module" as an expansion board. It seems very unlikely that such a thing won't be possible.

This would be really great. It is really amazing to see MBHP and derivative projects (like MB-6582) are offering such pro and open solutions.

Anyway I made up my mind over the week end. I will go for a MB-6582. If the STM32 upgrade is possible great. If not I could still sale it on the flea market with no SIDs :p

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MB-SID V3 is still a long way in the future... I won't even hypothesize about actual hardware design... some people might recall that MB-SID V2 was going to use PIC18F4620 and require two IIC_MIDI modules, which is how I designed the original MB-6582 "prototype"... and then that got superseded by PIC18F4685 and CAN bus master/slave comms. Luckily TK didn't change his mind on how stereo SID pairs would be controlled by one PIC. :)

True words! ;)

Currently I would say, that connecting a MBHP_CORE_STM32 module to a MB-6582 via CAN will give us the most powerful options, since PICs can be used to access the SIDs while STM32 is doing the sound engine, communication and user interface work.

If more than two SIDs would be connected to a single STM32 w/o the usage of additional microcontrollers, the firmware would mainly be busy to transfer data to the SIDs and wouldn't have so much time to calculate modulation sources and pathes - the problem: write accesses to SIDs have to be synchronized to the 1 MHz clock, this costs 2..3 SID cycles. While for a PIC this means the loss of 20..30 instructions, for a STM32 this means a loss of ca. 200 instructions per write access!

Another advantage of using PICs: STM32 could send some "background jobs" to the PICs which are handled in parallel. E.g., FM modulation or playing samples. They could be handled with incredible high speed (e.g. 20 kHz - note: a C64 usually accessed the SID with 50 Hz) without loading the "master processor".

There are two options I'm planning to evaluate in the next months before starting to program the firmware.

1) (over)clocking the SIDs with 2, 4 or 8 MHz! This would result into faster transfers. Disadvantage: lower frequencies cannot be played accurately anymore, and VCA envelopes are faster (*). Advantages: this could allow to handle 8 SIDs from a single STM32 w/o such a high performance loss. This could also allow to apply the ADSR workaround much faster, which means, that such an option could lead to the world-first "real SID" synthesizer with perfectly working ADSRs ;)

Note that this option would work with PICs as well, which means that re-using the PICs from an existing MB-6582 is again the most powerful solution, everything else is only a cost-saving measure.

/edit: (*) can also be seen as an advantage!

2) STM32 introduced a new connectivity line with derivatives which contain USB, two (!) CANs and an ethernet controller (unfortunately w/o PHY layer) beside of other useful peripherals.

Two CANs means even higher bandwidth, USB can be used in parallel, and integrated ethernet controller is the cherry at the top (MIOS32_OSC is already up&running, in addition it would be possible to download new patches directly from the internet ;))

These chips are not available yet, but it will be possible to prepare the firmware for such an upgrade option, which could be used for the final design.

Best Regards, Thorsten.

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  • 4 years later...

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