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USB Superspeed Peripherals

gean_3054931
Contributor II

Hello,

when fx3 is configured as slavefifo interface,if there is no data from the fpga(fpgs dont sends any data to fx3),what is the default state of buffer(the buffer which recieves the data from the fpga,i.e from p port)?

is it NULL buffer or is it contains some initial values?

regards,

geetha.

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1 Solution
YangyangC_06
Employee

Hello,

When you create a DMA channel by using CyU3PDmaChannelCreate, it will return the result. Once success, you will get a block of memory which is the DMA buffer. Every buffer created in the System memory has a descriptor associated with it.

In the DMA descriptor structure, the filed uint8_t *buffer is the pointer to buffer which will be used.

It is just like the case when you invoke malloc API in C language.

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3 Replies
YangyangC_06
Employee

Hi Geetha,

It is an empty area which without data. You could refer to chapter 5 of FX3 TRM

http://www.cypress.com/documentation/technical-reference-manuals/ez-usb-fx3-technical-reference-manu...

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gean_3054931
Contributor II

Hello,

it is an empty area,what empty area contains? or is it pointing to null?

regards,

geetha.

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YangyangC_06
Employee

Hello,

When you create a DMA channel by using CyU3PDmaChannelCreate, it will return the result. Once success, you will get a block of memory which is the DMA buffer. Every buffer created in the System memory has a descriptor associated with it.

In the DMA descriptor structure, the filed uint8_t *buffer is the pointer to buffer which will be used.

It is just like the case when you invoke malloc API in C language.

View solution in original post

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