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Re: DSP like MCUs, or MCU like DSPs?

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On 23/12/2022 09:14, Rick C wrote:
> On Friday, December 23, 2022 at 1:31:55 AM UTC-5, Paul Rubin wrote:
>> Rick C <gnuarm.del...@gmail.com> writes:
>>> I was just curious about what people have used for DSP
>>> applications, but in particular if anyone had used one of the
>>> "crossover" parts. So far, the answer has been "no".
>> I've done some audio stuff on ordinary CPU's, that in an embedded
>> system would probably go on something like a Cortex M4, if that's
>> what you call a crossover part. The next thing after that is
>> probably a GPU or FPGA, either of which contains a stupendous
>> amount of parallel MAC's. As others have said, dedicated DSP's are
>> now pretty niche.
>> 
>> FPGA's may have displaced general purpose processors for some
>> realtime applications as well, since you get low latency and
>> deterministic timing without having to go crazy worrying about
>> caches and interrupts.
>> 
>> I didn't personally work on it, but spent a while studying a 
>> cryptography app that ran on the now ancient Motorola DSP 56000
>> series. The model number came from the architecture's 24 bit words
>> and 56 bit MAC accumulator. The app wasn't particularly connected
>> with realtime or with signal processing. Rather, the 24*24->56 MAC
>> came in handy for high precision arithmetic used by the crypto
>> algorithm.
> 
> At that time there were generally, 16 bit fixed point DSP, and 32 bit
> floating point DSP.  Neither was appropriate for audio work.  16 bits
> is not enough resolution for high quality audio and 32 bit floating
> point was overkill, using extra power and burning extra dollars.
> Motorola came out with 24 bit devices as the sweet spot for high
> quality audio work.
> 

Yes.  There are many manufacturers of 24-bit DSPs, and they almost all 
have a background in audio.

Motorola (then Freescale, now NXP) also had a peripheral they called the 
TPU (Timer Processing Unit), found in microcontrollers aimed at engine 
control and advanced motor control usage.  The original version was 
16-bit and programmed in a weird kind of assembly, but the later 
versions were 24-bit and had a specialised C compiler.  It turns out 
that 16 bits is often not quite enough for many high resolution timing 
tasks, and again 32-bit would have been overkill.

(Now, of course, you just use the 32-bit - the millidollar difference in 
hardware costs is worth it for the added convenience.)

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DSP like MCUs, or MCU like DSPs? Rick C <gnuarm.deletethisbit@gmail.com> - 2022-12-21 09:30 -0800
  Re: DSP like MCUs, or MCU like DSPs? David Brown <david.brown@hesbynett.no> - 2022-12-22 14:36 +0100
    Re: DSP like MCUs, or MCU like DSPs? Grant Edwards <invalid@invalid.invalid> - 2022-12-22 15:54 +0000
      Re: DSP like MCUs, or MCU like DSPs? David Brown <david.brown@hesbynett.no> - 2022-12-22 21:56 +0100
        Re: DSP like MCUs, or MCU like DSPs? Grant Edwards <invalid@invalid.invalid> - 2022-12-23 01:40 +0000
          Re: DSP like MCUs, or MCU like DSPs? David Brown <david.brown@hesbynett.no> - 2022-12-23 09:38 +0100
    Re: DSP like MCUs, or MCU like DSPs? Dimiter_Popoff <dp@tgi-sci.com> - 2022-12-22 19:45 +0200
      Re: DSP like MCUs, or MCU like DSPs? Rick C <gnuarm.deletethisbit@gmail.com> - 2022-12-22 11:57 -0800
        Re: DSP like MCUs, or MCU like DSPs? Dimiter_Popoff <dp@tgi-sci.com> - 2022-12-22 22:24 +0200
        Re: DSP like MCUs, or MCU like DSPs? David Brown <david.brown@hesbynett.no> - 2022-12-22 22:03 +0100
          Re: DSP like MCUs, or MCU like DSPs? Rick C <gnuarm.deletethisbit@gmail.com> - 2022-12-22 17:11 -0800
            Re: DSP like MCUs, or MCU like DSPs? David Brown <david.brown@hesbynett.no> - 2022-12-23 10:48 +0100
              Re: DSP like MCUs, or MCU like DSPs? Rick C <gnuarm.deletethisbit@gmail.com> - 2022-12-23 03:44 -0800
        Re: DSP like MCUs, or MCU like DSPs? Paul Rubin <no.email@nospam.invalid> - 2022-12-22 22:31 -0800
          Re: DSP like MCUs, or MCU like DSPs? Rick C <gnuarm.deletethisbit@gmail.com> - 2022-12-23 00:14 -0800
            Re: DSP like MCUs, or MCU like DSPs? David Brown <david.brown@hesbynett.no> - 2022-12-23 10:54 +0100
              Re: DSP like MCUs, or MCU like DSPs? Clifford Heath <no.spam@please.net> - 2023-01-17 12:15 +1100
  Re: DSP like MCUs, or MCU like DSPs? dalai lamah <antonio12358@hotmail.com> - 2022-12-23 15:07 +0100

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