LPC 43XX USB DMA Engine Bulk Transfer maximum size ?

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LPC 43XX USB DMA Engine Bulk Transfer maximum size ?

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Contributor III

I have a LPC4357 design with USB0 as the USB host. I'd like to do 65K byte (128 block) BULK reads and writes to the SD cards i have attached. Seems i can get 63 bock size xfers (31K) thru fine - but nothing bigger. Ideally i'd like to get 64 (32K) or 128 (65K) Block read and write transfers to work. Is there a USB0 DMA engine limitation i'm missing ?

The USB0 xfers just don't complete when i tell t to do a 64 or bigger block size to the EHCI controller. 

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NXP TechSupport
NXP TechSupport

Kevin

From USB protocol, Bulk transfers are only supported by full and high speed devices. For full speed endpoints, the maximum bulk packet size is either 8, 16, 32 or 64 bytes long. For high speed endpoints, the maximum packet size can be up to 512 bytes long.The FS Max. bulk out packet size is 64 bytes.

Have a nice day,


Have a great day,
Jun Zhang

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Contributor III

The DMA size for BULK endpoints seems to be 16K. Its based on the number of bits in the xfer reg. Would be nice if it supported 65K like some other arm chips.  

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