AnsweredAssumed Answered

USB transfers slower with MQX 4.2 vs. MQX4.0

Question asked by Matt Housey on Jun 5, 2015
Latest reply on Apr 25, 2016 by isaacavila

I recently switch to MQX 4.2 from MQX 4.0 and the USB transfers have slowed considerably.

 

I modified MQX 4.0 per this link: https://community.freescale.com/thread/320155?q=usb%20transfer , which is changing delay_const in khci.c and USBCFG_DEFAULT_MAX_NAK_COUNT in host_cnfg.h. This sped up the USB transfers. I also did this with MQX 4.2 but it is much slower than 4.0.

 

I used _time_get_ticks to measure the time to open, write and close files on the USB with the following results:

                  

MQX            4.0          4.2

File open:     70 ms      80 ms

File write:     350 ms    1270 ms

File close:    0 ms        50 ms

 

How can I modify MQX 4.2 to perform as MQX 4.0 does?

 

Thanks,

Matt Housey

 

 

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