Stopping Quartus using multipliers?

Question

I'm prototyping a design on an Altera NIOS evaluation board with an EP2C35. The design will eventually be targeted at a much smaller device, possibly an EP2C5.

I have a couple of FIR filters that I want implemented in the FPGA fabric rather than in the dedicated multipliers so I can guage the footprint/performance. Quartus keeps using the multipliers and I can't work out how to stop it.

Can anyone help?

Nial

---------------------------------------------------------- Nial Stewart Developments Ltd Tel: +44 131 561 6291

42/2 Hardengreen Business Park Fax: +44 131 561 6327 Dalkeith, Midlothian EH22 3NU

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Mike Treseler · Accepted Answer

Could you code something that uses up all the multipliers?     -- Mike Treseler

Slurp · Answer

In the multiplier megafunction (LPM_MULT) on page 2 there are switches available to turn off the use of the chips dedicated multipliers and use logic elements instead.Slurp

Nial Stewart · Answer

available to turn off the

I'm inferring the multipliers so don't have this control unfortunately.

Nial

---------------------------------------------------------- Nial Stewart Developments Ltd Tel: +44 131 561 6291

42/2 Hardengreen Business Park Fax: +44 131 561 6327 Dalkeith, Midlothian EH22 3NU

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Nial Stewart · Answer

I suppose I could Mike, but it's a lot of hassle for what will hopefully just be a switch/constraint.

Nial.

---------------------------------------------------------- Nial Stewart Developments Ltd Tel: +44 131 561 6291

42/2 Hardengreen Business Park Fax: +44 131 561 6327 Dalkeith, Midlothian EH22 3NU

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Henry Wong · Answer

How about settingAnalysis and Synthesis settings-> More Settings-> Maximum DSP Block Usageto 0?  (Default -1)

Nial Stewart · Answer

Thanks Henry, that did it.I mistakenly presumed that -1 was a lower number than 0 and sochanging this to 0 wouldn't have made any difference.Intuitive isn't it :-)Nial----------------------------------------------------------Nial Stewart Developments Ltd        Tel: +44 131 561 629142/2 Hardengreen Business Park       Fax: +44 131 561 6327Dalkeith, MidlothianEH22 3NU

KJ · Answer

Must've been an unsigned -1 which would make it > 0 ;)KJ

Stopping Quartus using multipliers?

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