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PIC32MZ USB DMA

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c_bauer
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2017/07/22 03:19:11 (permalink)
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PIC32MZ USB DMA

Are there any Harmony samples that show how to use the DMA module when doing USB transfers?
 
Thank you!
Chris
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    RISC
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    Re: PIC32MZ USB DMA 2017/07/22 03:47:30 (permalink)
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    Hi,
    USB device ? USB HOST ?
    Which Harmony version ?
    What is your intent ?
    Regards
     
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    c_bauer
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    Re: PIC32MZ USB DMA 2017/07/22 05:02:01 (permalink)
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    I need a sample that runs the PIC32MZ in host mode for maximum throughput, for USB class <generic/vendor>.
     
    So afaik this poses at least three problems:
     - No vendor class USB Host sample in Harmony 2.03b
     - help_harmony.pdf has no section on how to implement a vendor-class Host yourself
     - USB module documentation "Section 51. Hi-Speed USB with On-The-Go (OTG)" is lacking vital info likewise
     
    For example if you look at project msd_basic, you have these functions
     - _DRV_USBHS_HOST_IRPTransmitFIFOLoad, and
     - _DRV_USBHS_HOST_IRPReceiveFIFOUnload,
     
    both decide whether or not to use DMA by calling _DRV_USBHS_HOST_GetFreeDMAChannel, which always return false, so they revert to manually loading the RX/TX FIFOs. Seems like a placeholder for later implementation.
     
    Our datalogger needs as much bulk bandwidth as possible, and it will be the only device connected to the PIC32.
    So we have a rather "dumb" device but it has Need for Speed(tm).
     
    Chris
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