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Stopping Quartus using multipliers?

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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Reply to
Nial Stewart
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Could you code something that uses up all the multipliers?

-- Mike Treseler

Reply to
Mike Treseler

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

Reply to
Slurp

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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Reply to
Nial Stewart

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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Reply to
Nial Stewart

How about setting

Analysis and Synthesis settings

-> More Settings

-> Maximum DSP Block Usage

to 0? (Default -1)

Reply to
Henry Wong

Thanks Henry, that did it.

I mistakenly presumed that -1 was a lower number than 0 and so changing this to 0 wouldn't have made any difference.

Intuitive isn't it :-)

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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Reply to
Nial Stewart

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

KJ

Reply to
KJ

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