LPC MicrocontrollersのトピックReasonable timeout in Mass storage class WaitForTransferComplete function

Reasonable timeout in Mass storage class WaitForTransferComplete function

ssudhir — Thu, 16 May 2019 13:53:20 GMT

Hi,

In Mass storage class – ehci.c file has a function called WaitForTransferComplete. This has a forever loop for bug catch and it gets invoked by HCDControlTransfer. So far it never got stuck there except today. We would like to add a reasonable timeout without compromising the normal operation. What would be the reasonable timeout?

Thanks

Re: Reasonable timeout in Mass storage class WaitForTransferComplete function

Alexis_A — Mon, 20 May 2019 15:55:35 GMT

Dear S.S,

Could you let me know which MCU are you using?

Best Regards,

Alexis Andalon

Re: Reasonable timeout in Mass storage class WaitForTransferComplete function

ssudhir — Tue, 21 May 2019 11:47:54 GMT

LPC4357

Re: Reasonable timeout in Mass storage class WaitForTransferComplete function

Alexis_A — Tue, 21 May 2019 17:39:11 GMT

Dear S S,

I was checking the example and this implementation was left blank.

This is depending of the implementation, in this example when using the commands to communicate with the device there's the next macro: MS_COMMAND_DATA_TIMEOUT_MS with the default value of 10000 ms.

Looking in other sources, the most common value is 5 seconds, so depending of your application you have a wide margin to implement this timeout.

Best Regards,

Alexis Andalon

Re: Reasonable timeout in Mass storage class WaitForTransferComplete function

ssudhir — Tue, 21 May 2019 18:27:31 GMT

Alexis,

Thanks for the response. When it times out, should it return any specific

error code or anything other than HCD_STATUS_OK is fine. Can we

return HCD_STATUS_TRANSFER_QUEUED?

Thanks

Re: Reasonable timeout in Mass storage class WaitForTransferComplete function

ssudhir — Tue, 21 May 2019 18:31:43 GMT

Alexix,

In the same file ehci.c beginning of the file there is a comment

// === TODO: Unify USBRAM Section ===

Any idea?

Re: Reasonable timeout in Mass storage class WaitForTransferComplete function

Alexis_A — Wed, 22 May 2019 19:59:32 GMT

Dear S S,

1-. Yes, you could try returning other status, only remember that the code will get stuck in the assert in the assert instrucction. Maybe after the timeout you could try a software reset or module reinitialization.

2.- It's important when a high speed stack is being used like USB or Ethernet that the storage is in a rapid access memory. That's why this buffers are being stored in the second section of SRAM

Let me know if this helps you.

Best Regards,

Alexis Andalon