7 Replies Latest reply on Mar 7, 2012 6:21 AM by anandsrinivasana_

what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint?

userc_44095 Mar 7, 2012 6:21 AM

Hi,everyone,

in the enfpoint descriptor, wMaxPacketSize's bit 12:11 is the number of transaction in one microframe for isochrounous endpoint .

so what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint? does it have the same meaning?

if so, when i set it to be 0x1c00---3 transactions in one microframe and 1024 maxpacketsize, the interrupt endpoint can't transfer anyword even i use the cyconsole.exe to test.

if the wMaxPacketSize's bit 12:11 for interrupt endpoint doesn't has the same connotation as the isochronous endpoiunt, the binterval define the minimum interrupt period as 125us. so 68013's interrupt endpoint can only transfer one packet in one microframe. obviously this is not right.

so i'm perplexed on the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint.

should somebody tell me? thanks a lot!

1. Re: what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint?

anandsrinivasana_ Mar 6, 2012 7:35 AM (in response to userc_44095)

If you send more than 1 packet in the microframe for iso and interrupt they're called high-speed high-bandwidth endpoints and the connotation is the same. How many packets are you trying to transfer and what is the behavior shown by Cyconsole.

Have you tried modifying the cystream firmware and have screamer/streamer do the transfer?

Regards,

Anand
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2. Re: what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint?

userc_44095 Mar 6, 2012 8:02 PM (in response to userc_44095)

Hi,Anand,

I'd like to send 3 packets in one microframe,

In the MaxPacketSize, bit15:13 must be 000b, bit12:11 represent the packets in one microframe, so if I want to transfer 3 packets I would set it to be 11b, bit10:0 represents the maximum size of one packet, if I want the packet size is 1024, so the bit 10:0 should be 10000000000b. so in my case it would be 1c00h.

but if i set the MaxPacketSize to be 1c00h in the endpoint descriptor, from the cyconsole.exe i can't even see the pipes/endpoints.

later on i read the code of cystreamer, it sets the  MaxPacketSize to be 1400h. and it do works well.

furthermore, i have read the code of the cystreamer several days ago, then i developed my application software, amazingly the speed approach 49MB/s with bulk transfer. ^_^

so i try to sue it in iso or interrupt transfer, but the interrupt only has 23.2MB/s.

anyhow, the 68013 is an excellent chip. ^_^

Best regards,

FuChy Ian
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3. Re: what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint?

anandsrinivasana_ Mar 6, 2012 8:53 PM (in response to userc_44095)

Even though iso and interrupt endpoint have guaranteed bandwidth you would be able to get a maximum of around 24 MB/s only per endpoint (limited by spec). Bulk on the other hand doesn't have guaranteed bandwidth but as long as the USB doesn't have too many devices connected you should be able to speed around 48MB/s. Maximum possible for Bulk as per spec is 53MB/s (taking overhead into account) but most controller can't transfer this much.

Regards,

Anand
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4. Re: what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint?

userc_44095 Mar 7, 2012 12:59 AM (in response to userc_44095)

Hello,Anand,

I know that the transfer theory about the iso and interrupt, and also the highest theoretical speed is 53.248MB/s.

I'm perplexed on the maxpacketsize in 68013. Although it matters little, I am still would like to grasp it.

Best regards,

Fuchy Ian
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5. Re: what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint?

anandsrinivasana_ Mar 7, 2012 2:50 AM (in response to userc_44095)

Please clarify your doubt regarding the maxpacketsize of cy7c68013 so that I can clear it.

Regards,

Anand
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6. Re: what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint?

userc_44095 Mar 7, 2012 5:47 AM (in response to userc_44095)

I'd like to send 3 packets in one microframe,

In the MaxPacketSize, bit15:13 must be 000b, bit12:11 represent the packets in one microframe, so if I want to transfer 3 packets I would set it to be 11b, bit10:0 represents the maximum size of one packet, if I want the packet size is 1024, so the bit 10:0 should be 10000000000b. so in my case it would be 1c00h.

but if i set the MaxPacketSize to be 1c00h in the endpoint descriptor, from the cyconsole.exe i can't even see the pipes/endpoints.
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7. Re: what's the connotation of bit12:11 in wMaxPacketSize for a interrupt endpoint?

anandsrinivasana_ Mar 7, 2012 6:21 AM (in response to userc_44095)

00 is for 1 packet per microframe

01 is for 2 packets per microframe

10 is for 3 packets per microframe

Regards,

Anand
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