[sdiy] uC with mul

[mikko.a.helin at nokia.com]

Also there might be some external hardware multipliers that could be used
with any uC.

DIL package is plus for DIYers. If we must use some higher density packages
anyway then there are many alternatives like TI MSP430F14x 

http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=MSP430F1
49

which is 16-bit RISC mixed signal uC with hardware 16x16 multiplier, two
UARTs and 12-bit ADC having $99 EVM including programmer, assembler, linker
and a limited functionality C-compiler. Samples are free I think ...

-Mikko


> -----Original Message-----
> From: ext Theo [mailto:t.hogers at home.nl]
> Sent: 03. January 2002 8:20
> To: Jim Patchell; synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] uC with mul
> 
> 
> That's a rather large ROM.
> Considering the added costs it might be cheaper to migrate to a
> MegaAVR with mult or move to a ARM part right away.
> 
> Theo
> 
> 
> From: Jim Patchell <patchell at silcom.com>
> 
> >      Here is a thought for doing an 8x8 multiply...use a 
> look up table.
> > If you use a 128Kx8 ROM, you can put a look up table in it 
> to make an
> > 8x8=16bit multiplier.  All you need are two 8 bit 
> registers, and then
> > use one of the address lines to access the MSB and LSB parts of the
> results.
> >
> >    Anyway, just a thought.
> >
> >    -Jim
> >
> > Scott Gravenhorst wrote:
> >
> > > I did quite a bit of assembly programming with a MC6800
> > > MPU (not 68K !) which has no mult instruction at all.
> > > There are cases where you need to multiply a variable
> > > number by a constant.  In these cases, a short sequence
> > > of shifts and adds does the trick and can be faster than
> > > using a generic multiply subroutine.  So if you are
> > > stuck with a no-mult mcu, or if you have 8x8 and need
> > > 8x16 or 16x16, this technique can be useful as well.
> > > Much depends on how fast the builtin 8x8 is.
> > >
> > >>> -----Original Message-----
> > >>> From: ext John Loffink [mailto:jloffink at austin.rr.com]
> > >>> Sent: 30. December 2001 17:08
> > >>> To: Byron G. Jacquot; synth-diy at dropmix.xs4all.nl
> > >>> Subject: RE: [sdiy] uC with mul
> > >>>
> > >>>
> > >>> The multiply cycle on the 68HC16 is 8 cycles.  Other micros
> > >>> do have the
> > >>> multiply instruction, usually multi cycle instructions.
> > >>> These might be
> > >>> good enough depending on your application, particularly for low
> > >>> frequency stuff like note generation, envelopes, LFOs,
> > >>> control sources,
> > >>> etc., but for anything related to analog synthesis it's
> > >>> generally better
> > >>> to have 12-16 bits of resolution to avoid stair-stepping.
> > >>>
> > >>> John Loffink
> > >>> jloffink at austin.rr.com
> > >>>
> > >>> -----Original Message-----
> > >>> From: owner-synth-diy at dropmix.xs4all.nl
> > >>> [mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Byron
> > >>> G. Jacquot
> > >>> Sent: Saturday, December 29, 2001 10:29 PM
> > >>> To: synth-diy at dropmix.xs4all.nl
> > >>> Subject: RE: [sdiy] uC with mul
> > >>>
> > >>>> Motorola M68HC16 microcontroller series has a 16 bit
> > >>>> multiplier/accumulator.
> > >>>
> > >>> The "little brother" 68HC11 could also do 8*8 multiply, and
> > >>> (IIRC) 16/8
> > >>> division.  They were both kinda slow.  I think a 
> multiply took 12
> > >>> cycles,
> > >>> and the divide something amazing like 42.
> > >>>
> > >>> Byron Jacquot
> > >>>
> > >
> > > =========================================================
> > > - Government: The other religion.
> > > - The media's credibility should always be questioned.
> > > - Lambs who lie down with lions are lunch.
> > >
> > > -- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
> > > -- Linux Rex         | RedWebMail by RedStarWare
> > > -- FatMan: home1.GTE.NET/res0658s/TekLab_FatMan_WebSite/index.html
> > >
> > >
> > >
> > >
> > >
> >
>