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Hot!DSPIC33EV256GM104

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RonGer
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2019/08/22 23:05:53 (permalink)
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DSPIC33EV256GM104

Dear all,
 
does anybody knows where I can find the RAM access time for the mentioned DSPIC33/ the time it takes to save 16bit on the RAM in the datasheets? Additionally I would require the information how this time gets extended by using a DMA.
 
Kind Regards
 
Ron
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4 Replies Related Threads

    JPortici
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    Re: DSPIC33EV256GM104 2019/08/23 00:11:52 (permalink)
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    I knew i should have told you on the other thread: use meaningful titles.
    It is annoying as hell and extremely confusing, as it is the same exact title as the other one.
    If this forum had any hint of moderation both your threads would have been closed and deleted without anybody helping you.
     
    Answering on the other one with the little i know
    #2
    RonGer
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    Re: DSPIC33EV256GM104 2019/08/23 00:20:27 (permalink)
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    Okay. Sorry I minded to late.
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    NKurzman
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    Re: DSPIC33EV256GM104 2019/08/23 00:46:17 (permalink)
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    The data sheet should list the number of cycles for each opcode.
    The same for DMA. Some chips have dual port ram. With those the DMA doesn’t slow down the main bus.
    #4
    du00000001
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    Re: DSPIC33EV256GM104 2019/08/23 01:28:59 (permalink)
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    RAM access time is a single Tcy, maybe 0.5 Tcy.
    DMA might take 2 Tcy for each transfer (as each transfer consists of a read and a write).
    Even if DMA takes 2 cycles and uses cycle stealing, this will be hardly recognizable unless you implement block transfers.
    Accessing SFRs doesn't account for a cycle as the DMA controller uses peripheral bus cycles not required by the CPU. (Unless you initialize all SFRs with the same value, the DMA peripheral bus will be available for DMA for a minimum of about every 2nd cycle.
    More is in the DMA chapter in the datasheet and in the FRM about DMA.

    PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
    #5
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