http://forums.leaflabs.com/topic.php?id=1943 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:08:49 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=1943#post-11419 Wed, 27 Jun 2012 11:42:40 +0000 manitou 11419@http://forums.leaflabs.com/ <blockquote><p> I think there are bugs in the way delayMicroseconds() works. That code is old and I don't understand it well, but I believe there may be a problem in the way we convert microseconds to busy-loop iterations (using STM32_DELAY_US_MULT in the current libmaple from Git). I seem to recall gbulmer picking apart the cycle timings in a post from a long time ago, so I'll try to dig it up and see if I can't find the bug. If anyone else wants to take a look at this, though, I'd really appreciate it. </p></blockquote> <p>The problem with a spin-loop for delayMicroseconds() is the jitter introduced by interrupts from systick, USB, and in this (IRremote) case the 50us-timer interrupt. For long delays (2400 us), then there are many cycles stolen from the spin-loop, and actual elapsed time will be longer than requested.</p> <p>There was another blog about passing 0 to delayMicroseconds() -- IRremote lib does make 0us requests in transmits for some IR devices -- and that is a problem with the delayMicroseconds() implementation because it does a us-- initially to account for function overhead ... </p> http://forums.leaflabs.com/topic.php?id=1943#post-11417 Wed, 27 Jun 2012 11:31:45 +0000 manitou 11417@http://forums.leaflabs.com/ <blockquote><p> Out of curiousity, would IrDA work for this purpose? Or it's not possible to use it like that? </p></blockquote> <p>I think not. I'm not real familiar with IrDA, but I think it is intended as a serial protocol between two IR devices -- baud rates, connections, link control ...</p> <p>The IR remotes don't have that kind of smarts and are hardwired with mark/space button encodings over 38 to 40 KHz carrier. </p> http://forums.leaflabs.com/topic.php?id=1943#post-11415 Wed, 27 Jun 2012 09:20:40 +0000 crenn 11415@http://forums.leaflabs.com/ <p>Out of curiousity, would IrDA work for this purpose? Or it's not possible to use it like that? </p> http://forums.leaflabs.com/topic.php?id=1943#post-11397 Tue, 26 Jun 2012 22:27:58 +0000 mbolivar 11397@http://forums.leaflabs.com/ <p>I think there are bugs in the way delayMicroseconds() works. That code is old and I don't understand it well, but I believe there may be a problem in the way we convert microseconds to busy-loop iterations (using STM32_DELAY_US_MULT in the current libmaple from Git). I seem to recall gbulmer picking apart the cycle timings in a post from a long time ago, so I'll try to dig it up and see if I can't find the bug. If anyone else wants to take a look at this, though, I'd really appreciate it. </p> http://forums.leaflabs.com/topic.php?id=1943#post-11389 Tue, 26 Jun 2012 18:11:12 +0000 manitou 11389@http://forums.leaflabs.com/ <p>Seems to work better by replacing delayMicroseconds(time) with<br /> <pre><code>unsigned int t1 = micros(); while((micros() - t1) &lt; time);</code></pre> <p>github was updated to reflect change. </p> http://forums.leaflabs.com/topic.php?id=1943#post-11388 Tue, 26 Jun 2012 17:00:36 +0000 manitou 11388@http://forums.leaflabs.com/ <p>This port of IRremote to maple may need further work -- the PWM timer duration for the IR transmit is controlled by delayMicroseconds() which seems to have considerable jitter. A call with 2400 results in a 2900 us delay. Such variations may or may not work with the IR equipment. I'll see if I can figure out effects of systick/USB on jitter.</p> <p>My initial proof-of-concept hack of the library (single C source file) was able to decode its own transmissions in a loop. But the full library implementation seems to have transmit timings out of tolerance for the decoder portion of the library. I'm still trying to figure that out... </p> http://forums.leaflabs.com/topic.php?id=1943#post-11361 Sun, 24 Jun 2012 18:14:46 +0000 manitou 11361@http://forums.leaflabs.com/ <p>Here is first cut at porting Arduino IRremote library to Maple. It uses a PWM timer for IR transmits and a 50us timer to sample IR input. Timers work for Maple RET6 -- change for your version of Maple.<br /> <a href="https://github.com/manitou48/maple-IRremote" rel="nofollow">https://github.com/manitou48/maple-IRremote</a><br /> Limited testing with Sony remote/VCR. </p> <p>Here is blog on Arduino library and current Arduino library<br /> <a href="http://www.arcfn.com/2009/08/multi-protocol-infrared-remote-library.html" rel="nofollow">http://www.arcfn.com/2009/08/multi-protocol-infrared-remote-library.html</a><br /> <a href="https://github.com/shirriff/Arduino-IRremote" rel="nofollow">https://github.com/shirriff/Arduino-IRremote</a> </p>