Focusing on one channel<\/strong><\/p>\n We have two channels to switch and pass on to the appropriate speakers. In the following we consider them\u00a0two independent systems. So we are going to change the image of the speakers we saw in Part I a little bit:<\/p>\n We have red speakers 1-16 for right channel and blue speakers 1-16 for left channel. In the following we\u00a0focus on one channel, so that we can easily describe what’s happening:<\/p>\n Later (as you can also see in the image) we shift the channels: When left channel is high, right channel is low. So the sound is wandering from a left speaker to a right speaker, then to the next left speaker an so on. We are up and running.<\/p>\n <\/p>\n Finding the path<\/strong><\/p>\n Finding the path is one of the the crucial tasks in this programming. As you remember we are using many relays to connect the appropriate speaker to the amp. What finding the path<\/em>\u00a0now means is, that we have to tell the relays with status to take. Let’s consider one relays switching two speakers:<\/p>\n One channel consist of a cable with two wires. First wire we connect to\u00a0both speakers. Second wire we will switch using a relay. \u00a0If we command the\u00a0relay to switch to “left” one speaker will play, if we command it to switch to “right”, the other one will play.<\/p>\n With multiple relays\u00a0we need multiple commands.\u00a0We now just replace “left” with 0 and “right” with 1 and connect two\u00a0relays to the first one:<\/p>\n <\/p>\n Here we could\u00a0already switch 4 speakers and the “path<\/em>” would be left-left (00) or left-right (01) or right-left (10) or right-right (11). You already get it. It is a binary system. A good example of just how easy (and close to all-day-problems like ours) binary systems can be. (We could also talk about a watering system for plants, where you\u00a0guide a water flow multiple times\u00a0left or\u00a0right with multiple gates.\u00a0It’s the same problem, but we’ll stick to speakers, I think it is nearly as easy to understand.)<\/p>\n Let’s now draw\u00a0the whole setting, complete with path<\/em> examples and how to calculate speaker numbers from paths and the other way round:<\/p>\n It’s very easy: The speaker number is the decimal (our “normal” numbers, based on the factor 10) representation of the\u00a0binary number describing the path<\/em>. Only starting with 0, so that we have to add 1 in case we want intuitively understandable numbers. See the examples in the image above.<\/p>\n <\/p>\n What’s missing?<\/strong><\/p>\n One thing is still missing, though: We now know the path but do not yet know which of the relays are to be switched. So for\u00a0example path<\/em> \u00a01011 will lead us to speaker 12. We have to:<\/p>\n while path<\/em>\u00a0 0011 will lead us to speaker 4 but\u00a0we have to:<\/p>\n Of course thins information is hidden\u00a0in our setting:\u00a0if we set the first relay to right, second number of the path<\/em> will of course be referring to relay 3, whereas if we set the first relay to right to left, the second number of the path<\/em> will be referring to relay 2. Just check the image and you see that it is obvious. We just have to find out how to do the math to get this information.<\/p>\n Let’s have a\u00a0look at the path<\/em> parts going left only:<\/p>\n 2-4-8, 5-10, 3-6-12, 7-14\u2026 you see the pattern: Next relay number is double the actual relay number –\u00a0in case the according path<\/em> digit is\u00a00 (left). In case the\u00a0according\u00a0path<\/em>\u00a0digit is 1\u00a0(right) same rule applies\u00a0but the result is is incremented\u00a0by 1 afterwards:<\/p>\n![\"speakers_fortl_channels\"](\"http:\/\/aboutmedia.notyet.me\/wp-content\/uploads\/2016\/10\/speakers_fortl_channels.png\")
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![\"relays_2_speakers\"](\"http:\/\/aboutmedia.notyet.me\/wp-content\/uploads\/2016\/10\/relays_2_speakers1.png\")
<\/a><\/p>\n![\"3_relays_path\"](\"http:\/\/aboutmedia.notyet.me\/wp-content\/uploads\/2016\/10\/3_relays_path.png\")
<\/a><\/p>\n![\"relays_paths\"](\"http:\/\/aboutmedia.notyet.me\/wp-content\/uploads\/2016\/10\/relays_paths.png\")
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![\"which_relay\"](\"http:\/\/aboutmedia.notyet.me\/wp-content\/uploads\/2017\/02\/which_relay-300x298.png\")
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![\"get_relay_number\"](\"http:\/\/aboutmedia.notyet.me\/wp-content\/uploads\/2017\/02\/get_relay_number.png\")
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