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