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Messages - GHinchliffe

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1
Discussion - Drivers / Poor throughput via USB Bulk transfer VNC2
« on: September 07, 2018, 11:15:40 AM »
Hi,
  I am building an adaptor device based around the Vinculum-II device.  This adaptor will need to maintain a throughput of around 170KB/s (bytes not bits), which should be easy via USB. 

However I am struggling to get anything above around 1.7 KB/s !!  If I strip out all mutex locks, semaphores and have the FTDI device simply throw away data it receives I manage to up that to about 10KB/s.  This is essentially just calling the IOCTL to read from the endpoint, in a loop with the maximum buffer size of 1024 bytes.  Data is being sent with a single libusb bulk transfer command from a linux host.

All USB tasks have a priority of 31, the task reading from USB is running at priority 20.  I have tried removing the vos_memset and vos_memcpy calls and this gets me an extra ~1KBs (but obviously renders the code useless)

Is there something obvious I could have overlooked? or is the VNC2 not capable of achieving the throughput I require? 


2
New Member Introductions / Hello
« on: July 27, 2018, 08:17:13 PM »
Hi,
  I am Graeme, officially I am a contractor (I prefer the term "code mercenary" :) ).  Have been writing code for far too many years, but always love working at low levels.  Spent a lot of time in my youth tinkering with assemblers on the 16bit home computers. 

  My current projects involve producing hardware and enhancements for old retro systems to improve development hardware for them or provide mechanisms to interface them with more modern technology, hopefully this will be the start of a line of interesting embedded projects.

  Recently I discovered the Vinculum-II device, and quickly acquired an EVAL board for them, the more I have read the more I have been impressed.  So here I am :)

3
Discussion - Software / Unable to allocate dynamic memory
« on: July 27, 2018, 08:10:02 PM »
Hi,
  I am having no luck in allocating any memory on a Vinculum-II device.  My code so far is very small, simply sets up a couple of test tasks, UART and then outputs strings via the UART. 

  When I attempted to use calloc to allocate some RAM (structure in question is 9 bytes), it returns a NULL.  I have tried with malloc also, same response even for a smaller value of 4.  I am linking in the stdlib.a library along with stdio.a ioctl.a errno.a uart.a and kernel.a

  I have also tried the call vos_malloc(4), which also returns a NULL.

A call to vos_heap_space gives me results of around 10KB for both free and maximum, so it seems like there is a heap configured and available.

Am I missing some crucial configuration command or option?  I assume that I should be able to allocate memory within a task?  I have also tried increasing the size of the task's stack (just in case :) ) and that has had no joy either.

Hope someone can point me in the right direction, thanks.

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