Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Joerg Newsgroups: comp.lang.forth,sci.electronics.design Subject: Re: ball-hours Date: Thu, 16 Oct 2014 11:58:25 -0700 Lines: 66 Message-ID: References: <5sho3adpfhed897nb8jdju99897ouhrvrv@4ax.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: individual.net 89LeV5GQkm6NHkjc9i50DA92YTIz74FpFrxeAcF/HMOXpe+C8X Cancel-Lock: sha1:mIK2AhcY5kt5t90vjzfwwW2xVLo= 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.lang.forth:33949 rickman wrote: > On 10/15/2014 11:42 PM, Raimond Dragomir wrote: >>>> ... Your other post seemed to be >>> >>>> talking about bitbanging the I2S port to the CODEC. How does that work >>> >>>> into the 100 MHz need? Bitbanging a serial port of any kind can be CPU >>> >>>> cycle intensive. >>> >>>> >>> >>> >>> >>> Yes, it is a major concern. We might need to hang an FPGA in there at >>> >>> least for TX, as a buffer, because essentially we are writing sine >>> >>> waves. Doesn't work on RX though, that's time-varying stuff. I hope I2S >>> >>> works for us, somehow. Got to find out. >>> >> Probably I'm plain wrong because I don't know anything about your >> application, but there are plenty ARM Corthex-M chips with I2S ports. >> For example, my LPC4088 has I2S with internal FIFO, separate PLL, etc. >> I can generate 48kHz 16bit audio stereo only with interrupts, no even >> need for DMA. My system runs at 120MHz. > Thanks. It doesn't mention TDM but could be a candidate if the arbitration in the I2S section is efficient. http://www.nxp.com/documents/data_sheet/LPC408X_7X.pdf > You only replied in the c.l.f group so he won't likely see your > response. I'm sure he is reading this in the s.e.d group. > > Some other devices have been mentioned to him already. Joerg is an > engineer with a lot of "preference". He won't use MCU parts from a > company he feels doesn't give good support so many of them are not in > the running. I know he has mentioned STM as a no-go. I don't know > about NXP. I do know that NXP ARMs have a huge and very active > community which can give good support. > A community is great and very useful. However for a product in a regulated market (on this one the FDA will have a say) sometimes it is necessary to obtain a written statement from the manufacturer. End of last year I had a case where NXP omitted something in the datasheet. It took major rattling of the cage to obtain an answer. That left a sour aftertaste. > I find it interesting that he wants to use a CODEC with an I2S port > which requires 8 channels (not always supported even if there is an I2S > port), but hasn't considered that in his selection criteria until now. > Well, I didn't start the search before yesterday and assumed that modern ARM processors would have no problem with that. Now I know that some do. -- Regards, Joerg http://www.analogconsultants.com/