http://forums.leaflabs.com/topic.php?id=1151 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:21:46 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=1151#post-7091 Sat, 05 Nov 2011 11:30:43 +0000 robodude666 7091@http://forums.leaflabs.com/ <p>Hopefully this has proven to be stable. Rastapopolos, it would be really awesome if you could send leaflabs a pull request on github or send them a diff patch so they can roll this into a future release. The boost in performance would be a great addition to the usb changes in the works.</p> <p>The <a href="http://leaflabs.com/docs/libmaple/contributing.html">docs</a> discuss how to contribute to libmaple. </p> http://forums.leaflabs.com/topic.php?id=1151#post-7085 Fri, 04 Nov 2011 12:17:40 +0000 gbulmer 7085@http://forums.leaflabs.com/ <p>Rastapopolos - Thank you for posting. This is a very big improvement, making a bunch of projects feasible. </p> <p>Hopefully LeafLabs will fold this into the next release. </p> http://forums.leaflabs.com/topic.php?id=1151#post-7084 Fri, 04 Nov 2011 11:38:49 +0000 Rastapopolos 7084@http://forums.leaflabs.com/ <p>Now, Windows but mostly Linux.<br /> How do i test the transfer rate ? Simply count the bytes per seconds and see if the<br /> data in the packets is the data i put in there.<br /> The transfer rate looks continuous but i haven't look into it. </p> http://forums.leaflabs.com/topic.php?id=1151#post-7083 Fri, 04 Nov 2011 09:41:49 +0000 gbulmer 7083@http://forums.leaflabs.com/ <p>Rastapopolos - thanks, found it.<br /> Yes, strange.</p> <p>AFAIK, VCOM_TX_EPSIZE is only used in the USB descriptor and that code, so it is a bit difficult to see what else it might be interacting with.</p> <p>700KBytes/second is very impressive. It is as quick as the best results I've seen for FTDI.</p> <p>What OS are you using?</p> <p>How are you testing the transfer rate? Is it continuous (i.e. exactly as you posted), or a burst? </p> http://forums.leaflabs.com/topic.php?id=1151#post-7082 Fri, 04 Nov 2011 04:47:14 +0000 Rastapopolos 7082@http://forums.leaflabs.com/ <p>I am using the latest source from git hub. You can find the same code in the IDE in "usb.c". </p> http://forums.leaflabs.com/topic.php?id=1151#post-7081 Fri, 04 Nov 2011 04:38:48 +0000 gbulmer 7081@http://forums.leaflabs.com/ <p>Rastapopolos - Which version of the Maple IDE are you using?</p> <p>I can't find the file 'usb_cdcacm.c', but I am using Mac.</p> <p>(Full disclosure: I am not a member of LeafLabs staff.) </p> http://forums.leaflabs.com/topic.php?id=1151#post-7080 Fri, 04 Nov 2011 04:03:24 +0000 Rastapopolos 7080@http://forums.leaflabs.com/ <p>Using SerialUSB to test the usb speed.</p> <p>// -- USB speed test --<br /> unsigned char buffer[64];<br /> void loop()<br /> {<br /> SerialUSB.write(bufffer, 64);<br /> }<br /> //---------------------</p> <p>I only got a 32kB/s transfer rate. :-(</p> <p>Looked into the code and found this:</p> <p>usb_cdcacm.c:<br /> --------------</p> <p>...<br /> #define VCOM_TX_EPSIZE 0x40<br /> ...</p> <p>// We can only put VCOM_TX_EPSIZE bytes in the buffer<br /> /* FIXME then why are we only copying half as many? */<br /> if (len &gt; VCOM_TX_EPSIZE / 2) {<br /> if (len &gt; VCOM_TX_EPSIZE / 2;<br /> }<br /> ...<br /> ------------------------------------</p> <p>Changed to: if (len &gt; VCOM_TX_EPSIZE) len = VCOM_TX_EPSIZE;</p> <p>And now with the same test i get 700 kB/s. :-)</p> <p>Changing the VCOM_TX_EPSIZE to 0x20 also works.<br /> this results in 600 kB/s.</p> <p>Doing two calls of 32 bytes doesn't work, only 32 kb/s.<br /> SerialUSB.write(bufffer, 32);<br /> SerialUSB.write(bufffer, 32);</p> <p>It seems that only when the buffer is filled completely to the VCOM_TX_EPSIZE in<br /> one go you get the high transfer speed. </p> <p>I am no usb expert but i think when the buffer is completely filled in one go<br /> it allows to send multiple packets per usb frame. </p>