Cypress Perform

Home > Design Support > Cypress Developer CommunityTM > Cypress Forums > USB Controllers > CY7C64713 : accessing endpoint RAM directly

Bookmark and Share
Cypress Developer CommunityTM
Forums | Videos | Blogs | Training | Rewards Program | Community Components



CY7C64713 : accessing endpoint RAM directly
Moderator:
RSKV

Post Reply
Follow this topic



CY7C64713 : accessing endpoint RAM directly

ossandust posted on 28 Apr 2009 3:31 PM PST
Member
6 Forum Posts
I'm using the CY7C64713, I only need Endpoint0 and Endpoint1..
I would like to use the 4KBytes of RAM, available for unused endpoints 2,4,6,8 as regular data RAM. Is this possible?
It seems like I can use following chunks without problem :
0xF000-0xF3FF
0xF400-0xF5FF
0xF800-0XFBFF
0xFC00-0xFBFF
I can't read/write correctly in the chunks
0xF600-0xF7FF
0xFC00-0xFFFF
Why is this? How should I configure the unused endpoints (EP2CFG ... EP8CFG) in order to enable use of the complete block of RAM?

Thanks!


Re: CY7C64713 : accessing endpoint RAM directly

ossandust posted on 28 Apr 2009 04:01 PM PST
Member
6 Forum Posts
Correction :
accessible/usable blocks : 0xF000-0xF5FF and 0xF800-0XFDFF
unusable blocks : 0xF600-0xF7FF and 0xFE00-0xFFFF




Re: CY7C64713 : accessing endpoint RAM directly

aasi posted on 29 Apr 2009 10:01 PM PST
Cypress Employee
1090 Forum Posts

you cannot convert endpoint buffers to usable blocks... 

Re: CY7C64713 : accessing endpoint RAM directly

ossandust posted on 29 Apr 2009 09:42 AM PST
Member
6 Forum Posts
Thanks for replying, Aasi!
Actually, I am already using most parts of the endpoint memory as regular data ram, this seems to work without problem. However I do notice that changing the endpoint configuration makes some parts of the memory unusable. I just can't find any logical relation between endpoint configuration and "freely usable" memory, and I wonder if there is a configuration which enables to use all memory (without using any endpoint functionality). I guess you are right, I might be using "unsupported" functionality which is not a wise thing to do - my current design unfortunately has grown so much that I'm in desperate need of extra data memory without doing a hardware redesign...


Re: CY7C64713 : accessing endpoint RAM directly

andrewsobotka posted on 29 Apr 2009 09:45 AM PST
Top Contributor
40 Forum Posts
See Chapter 8.5 of the Technical Reference Manual.

Endpoint buffers are always at least double-buffered. The problem you have uncovered is that in order to accurately support double-buffering, you only get to directly access half of the buffer.

So, for instance, Endpoint 4's buffer space goes from 0xF400-0xF7FF - 1024 bytes. Because you have EP4 configured as double-bufferd 512-bytes, you only get to access 0xF400-0xF5FF. The FX2 manipulates the other half of the buffer to provide the appearance of double-buffering.

You can try setting the EPxCFG bit 7 to 0 (the "valid" bit). This may or may not affect the situation.

Re: CY7C64713 : accessing endpoint RAM directly

ossandust posted on 29 Apr 2009 11:08 AM PST
Member
6 Forum Posts
Thanks andrewsobotka, you are spot on!
With this info of chapter 8.5 in mind, I had another look at the ram organization (fig.1-16 of the same manual) for the 12 possible configurations. There are a few configurations, which allow the CPU to access 0xF000-0xF3FF (EP2 double buffered 1024 bytes) and 0xF800-0xFBFF (EP6 double buffered 1024 bytes). Same for 0xF400-0xF5FF (EP4 double buffered 512 bytes) and 0xFC00-0xFDFF (EP8 double buffered 512 bytes). The 2 remaining memory regions are never used as "primary" memory in a double- or quad-buffered config. This must be the reason why I can't access exactly those 2 chunks, even when all endpoints are disabled ("valid" bit set to zero). Thanks for opening my eyes !




Re: CY7C64713 : accessing endpoint RAM directly

andrewsobotka posted on 29 Apr 2009 11:27 AM PST
Top Contributor
40 Forum Posts
You could also try configuring EP2 as quad-buffered 1024-byte and see if the memory opens up for you. Try doing it with the valid bit set and clear. It might be the case that quad-1024 will open up everything for access, and clearing valid will ensure that no activity causes the buffers to flip.

Re: CY7C64713 : accessing endpoint RAM directly

ossandust posted on 29 Apr 2009 04:36 PM PST
Member
6 Forum Posts
I believe I tried that before, but to make sure I retested this configuration (EP2 quad-buffered 1024) - it doesn't work. Which actually confirms what you pointed out earlier: I can only access the "first" memory chunk in a dual/triple/quad buffered configuration.




ALL CONTENT AND MATERIALS ON THIS SITE ARE PROVIDED "AS IS". CYPRESS SEMICONDUCTOR AND ITS RESPECTIVE SUPPLIERS MAKE NO REPRESENTATIONS ABOUT THE SUITABILITY OF THESE MATERIALS FOR ANY PURPOSE AND DISCLAIM ALL WARRANTIES AND CONDITIONS WITH REGARD TO THESE MATERIALS, INCLUDING BUT NOT LIMITED TO, ALL IMPLIED WARRANTIES AND CONDITIONS OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT OF ANY THIRD PARTY INTELLECTUAL PROPERTY RIGHT. NO LICENSE, EITHER EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, IS GRANTED BY CYPRESS SEMICONDUCTOR. USE OF THE INFORMATION ON THIS SITE MAY REQUIRE A LICENSE FROM A THIRD PARTY, OR A LICENSE FROM CYPRESS SEMICONDUCTOR.

Content on this site may contain or be subject to specific guidelines or limitations on use. All postings and use of the content on this site are subject to the Terms and Conditions of the site; third parties using this content agree to abide by any limitations or guidelines and to comply with the Terms and Conditions of this site. Cypress Semiconductor and its suppliers reserve the right to make corrections, deletions, modifications, enhancements, improvements and other changes to the content and materials, its products, programs and services at any time or to move or discontinue any content, products, programs, or services without notice.

Spec No: None; Sunset Owner: KXP; Secondary Owner: VWA; Sunset Date: 01/01/20