http://forums.leaflabs.com/topic.php?id=74172 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:17:58 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=74172#post-104990 Thu, 28 Nov 2013 13:49:27 +0000 samtal 104990@http://forums.leaflabs.com/ <p>Thanks guys.<br /> I got it! </p> http://forums.leaflabs.com/topic.php?id=74172#post-104989 Thu, 28 Nov 2013 13:28:28 +0000 gbulmer 104989@http://forums.leaflabs.com/ <p>samtal - arithmetic works correctly even when the unsigned number 'rolls-over'</p> <p>Try:<br /> <pre><code>uint32 curTime = 1; uint32 prevTime = 0xFFFFFFF0; uint32 diff = curTime - prevTime; Serial1.println(diff);</code></pre> <p>The number printed is 17 (1+16) </p> http://forums.leaflabs.com/topic.php?id=74172#post-104988 Thu, 28 Nov 2013 13:12:51 +0000 mlundinse 104988@http://forums.leaflabs.com/ <p>millis rollover is not a problem, shure the starttime is greater than the endtime when the rollover occurs in the intervall, but the difference will become a small positive number, when converted to unit16 it will still give you the correct number of milliseconds. </p> <p>Example:<br /> start time 10 mills before before rollover t0 = 2^32 - 10<br /> end time 65 millis after rollover t1 = 65<br /> elapsed time t1 - t0 = 65 - (2^32 - 10 ) = 65 + 10 - 2^32<br /> The 2^32 is truncated when using 32 bit registers, so the result will be 65 + 10 = 75 as it should </p> http://forums.leaflabs.com/topic.php?id=74172#post-104987 Thu, 28 Nov 2013 13:01:05 +0000 samtal 104987@http://forums.leaflabs.com/ <p>Thanks mlundinse.</p> <p>Your proposed solution is easy, but, as I wrote, the use of millis() will roll-over at some time (after 49 days from start) and will give erroneous time, while my device is planned to run continuously for years.<br /> I need a timer with 1 mSec resolution that that will count up to 30 seconds, and will restart for each cycle of my device (this will happen every few hours).<br /> A solution could be my 1000 mSec timer and a 16 bits counter.<br /> I therefore try to use one of the ST32 built-in timers.<br /> I have done this in the past by low level programming (timers registers), and I now try to use the high-level IDE Timer().<br /> I just don't know how to do it right! </p> http://forums.leaflabs.com/topic.php?id=74172#post-104986 Thu, 28 Nov 2013 12:18:03 +0000 mlundinse 104986@http://forums.leaflabs.com/ <p>Your timer doesnt count milliseconds, it counts to 1000 and then restarts.<br /> Use mills() and a variable uint32 time0 to record the starttime of the current state: </p> <p><code><br /> void loop()<br /> {<br /> int index = 0;<br /> uint32 time0;<br /> do<br /> {<br /> state = digitalRead(15);<br /> time0 = millis();<br /> while (digitalRead(15)== state) { } //loop wait for state change<br /> time[index] = (millis()-time0)&amp;0xFFFF; //Use elapsed number of millis to add time stamp to array.<br /> index++;<br /> }<br /> while (digitalRead(16));<br /> int i;<br /> for (i=0;i&lt;10;i++) //Print the array (testing)<br /> Serial1.println(time[i]);<br /> }<br /> </code> </p> http://forums.leaflabs.com/topic.php?id=74172#post-104985 Thu, 28 Nov 2013 11:43:47 +0000 samtal 104985@http://forums.leaflabs.com/ <p>Hi,<br /> I have a digital input channel that change state every few hundreds millis.<br /> I need to collect the state change times in an array with 1 mSec resolution.<br /> I can not use millis() because I need to restart at 0 each time.<br /> I try to use a Timer, but it gives me a random series of times rather than the real times.<br /> I am probably doing something wrong.</p> <p>Here is a test code:(that does not work as I expect)</p> <pre><code>HardwareTimer timer(1); uint16 time[20]; //Time stamp array uint8 state; uint16 counts; void setup() { timer.setPeriod(1000); Serial1.begin(115200); } void loop() { int index = 0; timer.setCount(0); //Zero and reset the timer. timer.resume(); do { state = digitalRead(15); while (digitalRead(15)== state) { } //loop wait for state change time[index] = timer.getCount(); //Add time stamp to array. index++; } while (digitalRead(16)); int i; for (i=0;i&lt;10;i++) //Print the array (testing) Serial1.println(time[i]); }</code></pre>