The maximum speed for the interrupt transfer for USB 2.0 full speed is 64kbytes/s. LPC2148 is used in device side. Is there a possibility of increasing the interrupt transfer speed by increasing the packet size. In that case generic device class wont support the device. Is there any possibility of moving to custom hid driver
Two things.
1) Who would claim your required bandwidth? Just make sure that you don't connect through a USB hub and no other device should be there to steal bandwidth on the cable.
2) Firewire allows allocation of way more bandwidth. Yes. Much more expensive. But you get what you pay for. If you do not want to take the cost of a bus designed to allow you to allocate x Mbit/s of dedicated bandwidth, then you will have to settle for what you can get from the standards you do pay for.
3) Or you may look into ethernet together with QoS.
Hello Westermark, Thanks for the reply. The problem in using bulk trnsfer is that application will be tested in the stress condition loading the PC with many other applications and it is expected to meet both guarantied data and time. Thats why the interrupt transfer was chose. So your opinion is the maximum packet size cannot be increased from 64bytes for interrupt transfer in any method? Our present scope is using usb 2.0 full speed only. Your suggession will be very helpful to me.
s/Two/Three/
Hello Westermark, Thanks for the reply.USB 2.0 full speed is the only scope. If we go for custom driver also the packet size increasing is not possible? Thanks in advance.
OK, Per. He is hard :-)
> The problem in using bulk trnsfer is that application will be tested in the stress condition loading the PC with many other applications and it is expected to meet both guarantied data and time. Thats why the interrupt transfer was chose.
Under stressed condition of PC, any transfer type can't guarantee transfer timing. No difference for bulk from interrupt. The interrupt bandwidth is guaranteed just on the USB wire. If PC device driver or your application can't pass transfer requests to the host controller in time, the guaranteed bandwidth is lost in vain.
> If we go for custom driver also the packet size increasing is not possible?
It can't. USB spec defines wMaxPacketSize of interrupt as up to 64 bytes in full-speed.
If you want to guarantee such a high transfer speed on full-speed, run it on bulk with a separated host controller (add-on PCI card for USB), so that the device can occupy full bandwidth. Or, insert a multi-TT hub between the bulk device and the PC.
Multi-TT hubs Belkin F5U234V1, F5U237v1 etc.
Tsuneo
Hi Tsuneo Thanks for the reply.For our application even if other devices are there in the USB bus it should guaranty data correctness and time. Thats why we chose interrupt transfer instead of bulk transfer. But we could find that the speed of interrupt transfer is not sufficient for our application. Any other possible solution? Thanks for helping me out Tsuneo.
Hi All, We are planning to buy Bulk based USB Driver. Can please you suggest me some.