STM32F105 USB Speed, Fifo size

elgerta · ‎2011-12-14

Posted on December 14, 2011 at 20:52

Dear all,

I've not found a related topic.

Right now I've checked with the demo of mass storage device the possible maximum transfer speed.

And it looks like ~500kByte/s, for writing to the device.

The define at usb_conf.h shows a RX_FIFO_SIZE of 128.

I thought I can increase the transfer speed by increase the RX_FIFO_SIZE, but with a value of e.g. 256, the USB init fails at while (bDeviceState != CONFIGURED);

So, is there a mistake from my side? Or to change other parts of the code to increase the transfer speed.

Target will be the value of ~1MByte/s.

Regards

Achim

rosarium · ‎2011-12-14

Posted on December 15, 2011 at 06:41

By only changing the fifo size is not enough.

You have to look into the state machine of BOT.

Do you capture any USB trace of your problem.

elgerta · ‎2011-12-18

Posted on December 18, 2011 at 20:27

I've forgotten that I use the demo from STM32_USB-FS-Device-Lib_3.3.0.

After your comment, I've look at the different functions from EP2_OUT_Callback(), Mass_Storage_Out(), USB_SIL_Read() and so on up to Write_Memory().

And at the end, Write_Memory() has a loop to add 8 times 64 bytes and then call MAL_Write().

So, it looks like that everthing transfer only 64 bytes.

I've measured the time for each function call of Write_Memory() but without writing to the mass storage.

Each 64 bytes, or each function call takes approx. 150µs.

8 functions calls with 64bytes takes approx. 1ms, which results in approx. 512kbytes/s.

Means I can't take every package during the 1ms frame.

If I'm right, fullspeed has 1ms frame time and max. 19 packets, and ~53µs for each packet?

But how many time between each packet?

If you mean a software like USB-Trace, right now no.

Has someone more experience with the STM32F105 and increased FIFO size together with BOT?

Is it possible to reach a transfe speed of ~800..900KBytes/s?

Regards

Achim