http://forums.leaflabs.com/topic.php?id=585 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:24:25 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=585#post-3240 Mon, 27 Dec 2010 17:31:41 +0000 mbolivar 3240@http://forums.leaflabs.com/ <p>millis() does use systick, as crenn said. however, delay() is currently implemented in terms of delayMicroseconds(), which is just an empirically determined busy-wait in assembly. see time.c for the details:</p> <p><a href="https://github.com/leaflabs/libmaple/blob/0.0.9/wirish/time.c" rel="nofollow">https://github.com/leaflabs/libmaple/blob/0.0.9/wirish/time.c</a></p> <p>the timers are initialized by default in init(), starting on line 68:</p> <p><a href="https://github.com/leaflabs/libmaple/blob/0.0.9/wirish/wirish.c" rel="nofollow">https://github.com/leaflabs/libmaple/blob/0.0.9/wirish/wirish.c</a></p> <p>since a timer's prescaler and reset values are shared across all channels, altering those will affect pwm on all pins associated with the timer. here is a table you may find useful:<br /> <a href="http://leaflabs.com/docs/timers.html#caveats" rel="nofollow">http://leaflabs.com/docs/timers.html#caveats</a> </p> http://forums.leaflabs.com/topic.php?id=585#post-3232 Mon, 27 Dec 2010 09:20:02 +0000 gbulmer 3232@http://forums.leaflabs.com/ <blockquote><p>Any reason for them to be turned on by default if they dont do anything?</p></blockquote> <p>Maybe partly because that's how the Arduino is set up. All of its timers are up and running. I am in favour of this because setting up the hardware is often one of the biggest hurdels for a beginner to overcome.</p> <p>I imagine it also makes some of the other code, like pwmWrite, a bit simpler if it can assume the timer is already going.</p> <p>Finally, the timers are doing something, they are running!-)<br /> So it is pretty straightforward to go look at a running timer to get a value. IMHO, this is very beginner friendly, and makes 'foraging' around the peripherals easier to get started on. </p> http://forums.leaflabs.com/topic.php?id=585#post-3230 Mon, 27 Dec 2010 06:17:51 +0000 General Tree 3230@http://forums.leaflabs.com/ <p>Great, thanks.</p> <p>Any reason for them to be turned on by default if they dont do anything? </p> http://forums.leaflabs.com/topic.php?id=585#post-3229 Mon, 27 Dec 2010 05:57:54 +0000 crenn 3229@http://forums.leaflabs.com/ <p>All of them are available to tweak. </p> http://forums.leaflabs.com/topic.php?id=585#post-3228 Mon, 27 Dec 2010 05:57:06 +0000 General Tree 3228@http://forums.leaflabs.com/ <p>By tweak I mean to change the period of the counting, or the prescaler, or even turn it off, without it hurting the functions mentioned above. </p> http://forums.leaflabs.com/topic.php?id=585#post-3225 Mon, 27 Dec 2010 05:46:53 +0000 crenn 3225@http://forums.leaflabs.com/ <p>I believe that the systick timer is used for delay() and millis(). What do you mean by tweak? </p> http://forums.leaflabs.com/topic.php?id=585#post-3224 Mon, 27 Dec 2010 05:42:10 +0000 General Tree 3224@http://forums.leaflabs.com/ <p>Hi everyone.</p> <p>Iv'e been playing with the timers, and saw that upon startup, timers 1-4 are already running by default.<br /> I was wondering which ones of them are used for functions like delay(), millis() etc.,<br /> and which ones are there for me to tweak.</p> <p>thanks </p>