- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
hello
i'm working on a data acquisition using the FX2LP chip , i have to make sure the data can be transfered at 20MHz per second last for at least 30 seconds , with no interrupt or delay. what transfer mode do i need ? can bulk mode be used in this situation?
thanks!
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
You should use ISO streaming. BULK transfer is handled by the OS if no other USB transfers are on the way. BULK is fast (40MB/s max) but can be interrupted by the OS. We measured up to 100ms idle with Windows XP....Windows 7 is better, but the problem is the same. If you use BULK, you have to add large hardware buffer for continous streaming. I think ISO streaming is better for you, with ISO you can transfer up to 24MB/s with guaranteed bandwith.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
thanks very much!
if i use bulk mode in this situation ,how large the hardware fifo do i need ? is there a method to caculate the deep of the hardward fifo?
and what is the best configeration of the fx2 slave fifo,512*4 or 1024*2 or others ?
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
Go with Iso only if your design can work with data loss bcoz iso does not do retry if packet is corrupt. Otherwise use interrupt endpoint, it has the guaranteed bandwidth like isochronous and retry if packet is corrupt.
Regards,
Anand
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
In terms of buffering, the more the buffering the better the performance.
Regards,
Anand