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Honored Contributor I
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read(10) with USB controller cy7c67200

Hello I use the cy7c67200 (EZ-OTG) on a fpga (Altera DE2-115). I successfully implemented The enumeration process and want to read now some data from a usb flash drive. But i have issues on that. Im not fully sure if I understand right how to do that, sadly i didnt found any examples which don't use high level frameworks and where i can see how i send CBWs (command block wrapper) and how i receive the CSW (Command Status Wrapper). 

 

Thats why i like to describe how i do it in the hope someone can tell me if I do it right in general . 

What i do is: i issue a bulk reset. 

 

Then i write a setup TD (Transfer Descriptor) which points with its BaseAddr to the CBW content. 

CBW (on position 0x50C): 

 

 

Signature: 

0x43425355 

 

 

Tag:  

0xfefefeed 

 

 

DataTransferLength 0x200 

 

 

Flags:  

0x8 

 

 

Lun:  

0x0 

 

 

Length: 

0xa 

 

 

CDB: 28 00 00 00 00 00 00 00 08 00 

 

My wMaxPacketSize as reported by the endpoint descriptor is 64 so i think I have to define the length in the CDB as 8 if i want 512bytes? 

 

 

TD (at position 0x500): 

base_addr: 0x50c 

port_length: 0x1c 

pid_ep: 0x12 

dev_addr: 0x2 

ctrl_reg: 0x41 

status: 0x0 

retry_cnt: 0x1b 

residue: 0x0 

next_td_addr: 0x528 

 

Then i write a (data) TD with PID_IN and point with the BaseAddr where i want the data should be written. 

 

TD (at 0x528) 

base_addr: 0x534 

port_length: 0x200 

pid_ep: 0x91 

dev_addr: 0x2 

ctrl_reg: 0x1 

status: 0x0 

retry_cnt: 0x1b 

residue: 0x0 

next_td_addr: 0x734 

 

Then i write a (status) TD which points with BaseAddr where i want to read the CSW 

 

 

TD(at 

0x734) 

 

 

base_addr: 0x740 

port_length: 0x0 

 

 

pid_ep:  

0x11 

 

 

dev_addr: 

0x2 

 

 

ctrl_reg: 

0x1 

 

 

status:  

0x0 

 

 

retry_cnt: 

0x1b 

 

 

residue: 

0x0 

 

 

next_td_addr: 0x0 

 

Then i set the CurrentTDPointer to 500 and wait until the HPI_STATUS register reports TDListDone. 

Then i read the data buffer at 0x534 where I expect the content from my usb device and i read the content 

from 0x740 where i expect my CSW content. 

 

But the data contains garbage, the csw signature for example is wrong and the csw tag is not equal to the value in my cbw. 

Also the data which should be the 512 bytes of the flashdrive from LBA: 0 are not identical with the contents from the flashdrive.
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