Dear Experts, I am using PDIUSBD12 from Philips in my embedded device. I am able to successfully enumerate the device from a Windows driver. I am using end point 1 IN/OUT for my data communication. I have successfully been able to write data from the device to Windows. But this was only one bytes at a time i.e. I write one byte to the end point buffer and issue the Validate Buffer command (0xFA) - work fine. Now in order to improve the throughput, I started writing 2 bytes at a time - works fine. But the moment I start writing 3 bytes in one shot, the communication stops and the Windows driver reports that the device responded with a BUFFER OVERRUN error (I get the following error code in the Windows driver - USBD status = C000000C (USBD_STATUS_BUFFER_OVERRUN). I understand that the buffer size in PDIUSBD12 is 16 bytes in size. Then why this buffer overrun? For your information I have a circular buffer into which the application software on my embedded device puts data. The the USB firmware pics data from this buffer and transmits it. Most of the data transmission happens from within the EP1 transmit ISR with the first byte being forcibly written by the application software to trigger a chain of interrupts causing the rest of the data bytes in the buffer to be transmitted. I want one more information - when a EP1 transmit ISR fires does it mean all the data bytes in its buffer have been transmitted or only one byte has been transmitted. Regards, Ganesh Okade Sunlux Technologies Ltd.
- posted
19 years ago
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