Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.fsmpi.rwth-aachen.de!news-1.dfn.de!news.dfn.de!news.informatik.hu-berlin.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Joerg Newsgroups: sci.electronics.design,comp.arch.embedded Subject: Re: AREF bypass capacitance on ATMega2560? Date: Sun, 08 Sep 2013 15:57:29 -0700 Organization: Consultant Lines: 58 Message-ID: References: <87y579yr74.fsf@devereux.me.uk> <7xfvtggynf.fsf@ruckus.brouhaha.com> <4e6p29h94rt39naaue6p0k1gqra33h7vf0@4ax.com> <6imp291k8t3li7pa63ddj94dh3l21gqeqp@4ax.com> Reply-To: news@analogconsultants.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: individual.net sZB55Wczh32PcLh6fQH3ngEtZMdEKknZ1h1VCx++d1JILrxToC Cancel-Lock: sha1:pxl1QgUraX7D10er4JLPFRVYfzw= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.6) Gecko/20070728 Thunderbird/2.0.0.6 Mnenhy/0.7.6.666 In-Reply-To: Xref: csiph.com comp.arch.embedded:13403 krw@attt.bizz wrote: > On Sun, 08 Sep 2013 14:20:46 -0700, Joerg > wrote: > >> krw@attt.bizz wrote: >>> On Sun, 08 Sep 2013 09:34:38 -0700, Joerg >>> wrote: >>> >>>> krw@attt.bizz wrote: >>>>> On Sat, 07 Sep 2013 15:23:39 -0700, Joerg >>>>> wrote: >>>>> >>>>>> rickman wrote: >>>>>>> On 9/7/2013 4:46 PM, Joerg wrote: >>>>>>>> Paul Rubin wrote: >>>>>>>>> Joerg writes: >>>>>>>>>> I don't see how the equivalent of a TMS320 or a big MSP430 could fit >>>>>>>>>> into one of these small Lattice devices. >>>>>>>>> I had thought the parts of those processors that would bloat up badly >>>>>>>>> (instruction decode etc.) are pretty simple so the overall effect of the >>>>>>>>> bloat is ok in the scheme of things. The parts doing the most work >>>>>>>>> (memory, arithmetic) are done in the FPGA hardware (RAM and DSP blocks, >>>>>>>>> adders connected to the LUT's somehow) as efficiently as on the MCU's. >>>>>>>>> >>>>>>>>> I do think softcores seem like a silly idea a lot of the time, and am >>>>>>>>> looking forward to more low end FPGA's with MCU blocks. >>>>>>>> Much of it has to do with legacy code. Yes, some things could even be >>>>>>>> done more efficiently in the FPGA because you can actually streamline >>>>>>>> the HW to the task, something neither uC nor DSP allow. For example, why >>>>>>>> have a 32-bit HW multiplier when you know you'll never exceed 23 bits? >>>>>>>> But legacy code won't run anymore and you need FPGA specialists to make >>>>>>>> it all work. >>>>>>> No, you would need a DSP specialist. The FPGA designer only needs to >>>>>>> know how to code the FPGA. >>>>>>> >>>>>> So for this kind of solution in an FPGA you need a DSP specialist and an >>>>>> FPGA specialist? That would be a problem. >>>>> Pick ones that are in the automotive market. Support for fifteen >>>>> years is required. >>>>> >>>> That's a good point. How does one find out which ones those are? >>> Click on the "Automotive" tab on the applications page in their web >>> site? Look for the ACQ- compliance designations? >>> >> I usually go in via Digikey. No automotive tab in that segment but the >> temperature range gives it away. > > Not at all. Automotive and industrial temperatures are quite alike > but the qualifications certainly are not. Automotive needs 85C > ambient. What that does to Tj varies by component. 85C in a vehicle? Yikes. I would not dare to design that in. -- Regards, Joerg http://www.analogconsultants.com/