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5 Pierogi Universal Infrared Remote Control
11 <img src="PierogiIcon.png">
13 <img src="PierogiIcon.png">
16 <h2 align="center">A Universal Infrared Remote Control App for the Nokia N900</h2>
18 <p>Welcome to the Pierogi website! This web page and the app itself are
19 still under active construction. Until I have time to construct a proper
20 home page, I'll just place a copy of the app's internal documentation below.
21 If you have any questions or comments, please post a note on the
22 <a href="https://garage.maemo.org/forum/?group_id=2286">Pierogi forum boards</a>
24 <a href="mailto:jpietrzak8@gmail.com">jpietrzak8@gmail.com</a>.
25 Thank you for your understanding.
28 <h1>Pierogi Documentation</h1>
31 The Pierogi universal infrared remote controller is a single self-contained
32 app capable of sending IR commands to a wide variety of devices.
33 At the moment, it is oriented towards television, VCR, DVD, and Blu-ray
34 devices, but a few other types of device have had their command sets entered.
38 In this app, each family of related infrared commands is collected into a
39 "keyset". As manufacturers commonly reuse a given set of commands rather
40 than re-invent the wheel each time they come out with a new product, many
41 devices can share the same keyset.
45 Pierogi also follows the classic concept of a universal remote, by having
46 a common set of buttons that are reused for each device. So, for example,
47 the "power" button has the same name and is located in the same position,
48 no matter what keyset is currently in use -- even if that keyset has a
49 different name for "power", or has no "power" command at all. (Check out
50 the <a href="http://en.wikipedia.org/wiki/Universal_remote">Universal
51 Remote wiki</a> for a description of universal remote controls, which
52 includes a special mention of the N900!)
56 So in short, to use Pierogi, you first select an appropriate keyset, then
57 press the appropriate buttons to control the target device. More detail on
58 the features of Pierogi is provided below.
61 <h2>Using Pierogi</h2>
64 The current Pierogi design is built around a tabbed window, each tab containing
65 a group of related buttons. Depending on the keyset that has been selected,
66 some of these buttons will be active, others inactive. Active buttons are ones
67 which have been associated with a command in the current keyset. Pressing an
68 active button will begin repeating the associated command; letting up on the
69 button will stop the command.
73 Keysets can be chosen using the "Select Keyset" option in the drop-down menu.
74 If you have a particular keyset you use often, it can be stored in the
75 "favorites" tab for quick access.
82 <img src="MainTab.png">
84 <p>The Main tab contains just the power, volume, mute, and channel buttons.
85 It is intended to be a quick way to get to the most important, commonly used
86 controls. The name of the current keyset is also provided in this tab.</p>
90 <img src="UtilityTab.png">
92 <p>The Utility tab contains a selection of commonly useful controls, such as
93 "Sleep", "Input", "Closed Captions / Subtitles", and the color buttons.
94 This tab is intended to be a quick way to reach the most frequently used
95 buttons; as such, the selection may be updated in future versions of Pierogi.
100 <img src="KeypadTab.png">
102 <p>This tab provides a numeric keypad and a handful of associated commands,
103 intended mainly for use with televisions. The "Prev Channel" button should
104 take you to the previously selected channel, if any. The "Dash" button
105 should allow you to specify a digital subchannel, as in "16-4". The "+100"
106 button is used for television sets which normally expect only two digits
107 per channel; using this button allows you to enter a third digit. The "-/--
108 Double Digit" button is used on very old televisions that normally expect
109 channels to be represented by just a single digit; pressing this should
110 allow you to enter a second digit.</p>
114 <img src="MenuTab.png">
116 <p>This tab contains buttons used to enter and exit a menu, navigate within
117 a menu, and select menu entries. The "Menu" button is meant to enter the
118 main system menu of a given device; "Guide" is a content-related menu available
119 on many modern devices; and "Disc Menu" is used to access the menu interface
120 provided with DVD and Blu-Ray media.</p>
124 <img src="MediaTab.png">
126 <p>Many of the most important playback commands are represented on this tab.
127 "Play", "Pause", and "Stop" are the most common ones, along with "Reverse"
128 (often called rewind) and "Fast Forward". A variety of other less common
129 navigation controls are included, along with the "Eject" command.</p>
131 <h4>Favorite Tab</h4>
133 <img src="FavoriteTab.png">
135 <p>As there are numerous keysets available in Pierogi, a "Favorite" tab has
136 been implemented. To add a favorite keyset to the tab, first select that
137 keyset from the "Select Keyset" window. Then, navigate to the Favorite tab
138 and press "Add Current Keyset".</p>
140 <p>Once you have added some keysets to the favorites list, you can tell
141 Pierogi to use one by simply selecting that keyset from the list.</p>
143 <p>A keyset can be removed from the list by selecting it and pressing
144 "Remove Selected Keyset".</p>
146 <h3>Select Keyset Window</h3>
148 <img src="SelectKeysetWindow.png">
150 <p>The Select Keyset window presents a list of all the keysets currently
151 available in Pierogi. As this list is fairly long, buttons have been added
152 at the top of the window to choose the make and/or type of device for
153 the product you are trying to control; all keysets not associated with
154 the chosen values will be hidden. To use a keyset,
155 simply select it from the list, and close the window (by pressing the
156 return arrow at the top right of the screen).</p>
158 <h3>Secondary Buttons Window</h3>
162 <img src="TVTab.png">
164 <p>This page contains several more TV-oriented buttons, including controls for
165 picture-in-picture, teletext, and some graphics and audio controls. The
166 content of this page is subject to change.</p>
170 <img src="Media2Tab.png">
172 <p>This is another page of media buttons, containing a mix of commands useful
173 for DVD players, VCRs, audio devices, and possibly other devices. The content
174 of this page may change in the future.</p>
178 <img src="InputTab.png">
181 Many devices have multiple sources for their data, whether it be television
182 signals piped in over the air or through a cable, or audio from a variety of
183 stereo components. It is unlikely that Pierogi will ever be able to list all
184 of the various possible input buttons, but this tab contains a few of them.
189 <img src="AdjustTab.png">
192 A handful of the various audio and video adjustment buttons are placed on
193 this tab. Actual volume controls will likely remain on the main window,
197 <h2>Design Rationale</h2>
199 <p>Here I collect my thoughts on the how and why of creating Pierogi.</p>
201 <h3>Hasn't this been done before?</h3>
203 <p>Yes, remote control software has already been written for the N900. In
205 <a href="http://irreco.garage.maemo.org/">Irreco / QtIrreco</a> project
206 creates beautiful virtual remote controls. I've also used the
207 <a href="http://thp.io/2010/raemote/">Raemote</a> widget to control my Apple
208 computers. But these programs have their shortcomings; in particular, they
209 are not universal. Each simulated remote control in QtIrreco is a completely
210 separate animal. I would like to have a standard set of buttons that I can
211 use on all sorts of different hardware.</p>
213 <h3>What's up with LIRC?</h3>
215 <p>Just as QtIrreco and Raemote do, I want to leverage the work of the
216 <a href="http://www.lirc.org/">Linux Infrared Remote Control</a> project.
217 The LIRC project is by far the most influential open-source effort working
218 with consumer IR. And the N900 comes with a device driver made
219 specifically for their server! But, you see, I have a problem. I
220 don't want to do things the way LIRC wants to do things.</p>
222 <p>The N900 is different from other Linux systems using IR -- rather than
223 being the machine at which you point a remote control, this machine <i>is</i>
224 the remote control. This is not what LIRC was designed for; the heart of the
225 LIRC project is a server that will sit and wait for messages to arrive from
226 the IR system. Although it can also broadcast IR data back out (when using
227 hardware that supports 2-way IR communication), that is not its primary
230 <p>I believe there are three disadvantages to using the LIRC server as it
231 currently exists. First, there isn't much point to running a daemon on
232 the N900 to manage the IR device; no messages are ever going to come in from
233 the output-only hardware on the N900, so why sit and listen for them?</p>
235 <p>The second problem is somewhat larger. LIRC uses configuration files to
236 describe the command set for each remote control. And there are a lot of them.
237 A whole lot. We're talking thousands of files here, and each file can describe
238 many remote controls. This is not a problem for Raemote or Irreco, as they
239 only need to deal with one config file at a time. But if you're aiming to
240 manage the whole lot of them, you need to find a way to deal with the
243 <p>The third problem is more subtle, but really tough to crack. You see, the
244 whole point of LIRC is to take the commands it receives from the IR port and
245 translate them into something recognizable. As such, each config file provides
246 a mapping from numeric commands to human-readable strings. This is a
247 serious problem, if your interest is in finding similar commands in
248 different config files! Take, for example, the "power"
249 button found on most remote controls. In some config files, the string for
250 this is "power". Others have "Power", or "POWER". You can also find "pwr",
251 "PWR", "ON/OFF", "ON-OFF", "ONOFF", "POWER_ON_OFF", "KEY_POWER", "Operate",
252 "Standby", and who knows what else. And, you've gotta be careful not to get
253 confused by strings like "SUBTITLE_ON/OFF" or "TV_ON_TIMER". How is an app to
254 know which key to map all these strings to?</p>
256 <h3>So how is Pierogi different?</h3>
259 Pierogi attempts to answer these problems. First, it talks directly to the
260 /dev/lirc0 device, no server middleman needed. Yes, you can use Pierogi
261 without the LIRC daemon running; in fact, there's no need to ever install it.
262 Second, Pierogi is built
263 around the concept of the "keyset"; all IR codes that can share the same
264 protocol without interfering with one another are combined into a single
265 family of related commands. In short, this reduces the quantity of data
266 available from LIRC config files to something much more manageable.</p>
268 <p>The third problem mentioned above is a bit harder to solve; I'm currently
269 mapping each LIRC string to a corresponding Pierogi key by hand. Naturally,
270 this process will be fraught with errors; I intend to keep updating Pierogi
271 as these errors are found and fixed.
274 <h2>Internal Design Notes</h2>
276 <p>If you're interested in the ugly details of the code, read on!</p>
278 <h3>What's up with the name of this app?</h3>
280 <p>Lately I've been naming my projects after tasty foods. In particular,
281 I've been working my way through the pasta-oriented dishes. (My previous
282 project, "Linguine", has gotten bogged down, so I moved on to this one...)</p>
286 <p>I'm a C++ kind of guy, it just makes sense to me to use a C++ kind of
287 interface. The Qt classes have everything you need to set up a decent UI,
288 and Qt Creator makes coding up a project for the N900 relatively
289 painless. Check it out for yourself at
290 <a href="http://qt.nokia.com/">the Qt webpage</a>.
293 <h3>The simplest device ever!</h3>
295 <p>If you ever wanted to learn how to work with device drivers on Linux, the
296 N900's infrared port is the device you want to start with. It's not
297 much more than a flashlight: You turn it on. You turn it off. You turn it on
298 again. You turn it off again. You really can't get much simpler than that.
299 Interaction with the "/dev/lirc0" device involves no more than handing
300 it an array of integers: the first integer being an amount of time to keep the
301 light lit (in microseconds), the second being an amount of time to leave it
302 switched off, the third on, the fourth off, and so on.</p>
304 <p>Well, ok, so it involves just a little bit more than that. You don't want
305 to leave the light stuck in the "on" state when you are finished, so the driver
306 demands that the last item in every array be an "on" amount -- after finishing
307 that timer, the IR will stay off until the next command arrives.
311 Also, in an attempt to weed out any confusing signals from natural IR sources
312 in the environment, consumer IR devices are "pulsed" at a particular
313 frequency. So you're really turning a strobelight on and off, not just a
314 flashlight. When the receiver sees that the light is coming from a strobelight
315 pulsing at the desired frequency, it can be assured that that signal came from
316 an actual remote control. The N900's device driver allows you to set the
317 frequency anywhere between 20000 Hz and 500000 Hz. 38000 Hz seems to the most
318 popular frequency used by modern remote controls, at least from what you find
319 in LIRC config files. Also, you can set how long each pulse needs to be held,
320 in terms of a percentage: 25% means turning the light on for just one quarter
321 of the pulse, 33% means leaving it on for one third, etc. This is called the
322 "duty cycle", and can be anywhere between 0 and 100 percent. LIRC's default
323 duty cycle is 50 percent.
326 <p>And that's about it. I've been using a
327 <a href="http://svn.jacekowski.org/host_mode/trunk/drivers/input/lirc/lirc_rx51.c">web page</a>
328 that lists the source code for the IR device driver. I'm not sure if there's
329 a better location out there for N900 source code, but this seems accurate
332 <h3>You did <i>what</i> to the LIRC daemon?</h3>
335 Well, ok, yeah, I've cannibalized the transmission code out of the LIRC
336 server and dumped it into my app. Sort of. I can't really keep my hands off
337 of code once I've seen it, so I've rewritten it in C++, reorganizing it in
338 an object-oriented manner along the way.</p>
341 As I have progressed in adding support for additional IR protocols, I'm
342 beginning to see why the authors of the LIRC made the attempt to compress
343 every possible IR protocol into a straightforward count of individual IR
344 pulses. The total number of IR protocols in use is amazing, and many of them
345 (through oversight or due to the longevity of their use) are mind-numbingly
346 complicated to deal with. Still, I believe that separating the major protocols
347 into their own code paths results in code that is easier to understand and
348 maintain; I'm slowly moving away from the LIRC's system to my own as time
353 In any case, I owe the LIRC authors a deep debt of gratitude for their
354 efforts. If you are one such author, thank you. As Pierogi is more-or-less
355 derived directly from their work, it is also licensed under the same terms,
356 the GNU General Public License (GPL) version 2 or later.
361 <p>I've fallen in love with the Gentleface Mono Icon Set. Of the creative
362 commons icon sets available, theirs stands head and shoulders above the rest.
363 Find their work at <a href="http://www.gentleface.com">www.gentleface.com</a>.
367 <p>A set of links to some resources I've used while writing the code.</p>
370 <li>The center of the Linux infrared world, the
371 <a href="http://www.lirc.org/">Linux Infrared Remote Control</a> project.
373 <li>A <a href="http://en.wikipedia.org/wiki/Consumer_IR">Wiki page</a> with
374 general info on consumer IR
376 <li>A <a href="http://www.sbprojects.com/knowledge/ir/index.php">good introduction</a>
377 to the theory and practice behind consumer IR devices
379 <li>A <a href="http://en.wikipedia.org/wiki/RC-5">Wiki for the RC-5 protocol</a>
381 <li>Some <a href="http://www.sbprojects.com/knowledge/ir/nec.php">Info on the NEC protocol</a>
383 <li>Some <a href="http://www2.renesas.com/faq/en/mi_com/f_com_remo.html">More info on the NEC protocol</a>
385 <li>An introduction to the <a href="http://www.sbprojects.com/knowledge/ir/sirc.php">Sony SIRC protocol</a>
387 <li>An excellent collection of <a href="http://www.hifi-remote.com/sony/">Sony command codes</a>
389 <li>Link to (what appears to be) source code for the N900's
390 <a href="http://svn.jacekowski.org/host_mode/trunk/drivers/input/lirc/lirc_rx51.c">/dev/lirc0 device driver</a>.
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