add article about KSP Hack

content.org

@@ -1,3 +1,6 @@
+:PROPERTIES:
+:ID:       5116403f-0c79-4ccf-a33a-fdcc66f08bcc
+:END:
 #+hugo_base_dir: site
 #+hugo_section: posts
 #+STARTUP: logdone
@@ -2758,6 +2761,108 @@ Butterfabrik benutzten, ehemaligen Schiffsmotor!
 
 Und jetzt gehts schlafen.  Bis nächste Woche in Deutschland.
 
+** Hacks                                                    :@Hacks:
+***  Converting a Kawai KSP-30 to pure MIDI
+CLOSED: [2021-08-27 Fri 21:57]
+:PROPERTIES:
+:EXPORT_FILE_NAME: converting-a-kawai-ksp-30-to-pure-midi
+:END:
+
+My Kawai KSP-30 digital piano has been on its last leg for some time
+now. To get it to work at all, I had to unplug the amplification
+circuit whose interface on the main PCB was burnt out. Of course is
+wasn't of much use by itself after that bit of crude surgery but
+worked fine as a midi keyboard.
+
+#+CAPTION: The main PCB.
+#+DOWNLOADED: screenshot @ 2021-08-27 18:05:08
+[[file:static/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-05-08_screenshot.png]]
+
+There must have been some creeping currents because the piano got more
+and more unreliable requiring hectic powercycling to boot and finally
+not booting at all. Looking for spare parts on eBay didn't bring up
+anything so I decided to scan the keyboard directly with a
+micro-controller and do away with the rest of the innerts of my trusty
+Kawai entirely.
+
+First I had to find out how the keyboard matrix was scanned. Luckily I
+had a logic analyzer lying around to test the ports on the keyboard
+connector [fn::Before I remembered having a logic analyzer however, I
+fried my Raspberry Pi with the 5V logic :P.]
+
+#+CAPTION: Figuring out the keyboard matrix.
+#+DOWNLOADED: screenshot @ 2021-08-27 18:15:55
+[[file:static/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-15-55_screenshot.png]]
+
+Furthermore, I found the service manual for the KSP on =archive.org=
+and with a little trial and error was able to puzzle it together.
+
+#+CAPTION: The keyboard connector.
+#+DOWNLOADED: screenshot @ 2021-08-27 18:26:41
+[[file:static/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-26-41_screenshot.png]]
+
+The keyboard matrix has eight columns that can be read through =KD0=
+through =KD7= [fn::Annoyingly the KDX numbers are shifted by one at
+other places in the manual]. To scan all 88 keys three multiplexers
+are employed that can be enabled individually by the =SA4= and =SA6=
+ports (see figure above). The other three =SAX= connectors select one
+of eight rows through the currently enabled multiplexer. Because the
+piano is velocity sensitive, each key actually has two sensors with
+one triggered shortly before the other. The time difference between
+these signals can be measured to obtain the key velocity. Therefore
+the =KDX= ports are split into two groups =S1= and =S2= that
+correspond to the two triggers.
+
+#+CAPTION: The two-switch mechanism.
+#+DOWNLOADED: screenshot @ 2021-08-27 18:35:47
+[[file:static/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-35-47_screenshot.png]]
+
+Putting all this together one arrives at the following matrix.
+#+DOWNLOADED: screenshot @ 2021-08-27 18:37:23
+[[file:static/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-37-23_screenshot.png]]
+
+In practice one just cycles through the multiplexers while running a
+counter to obtain the correct note because they are consecutive.
+
+Having ascertained all this knowledge I began the realization of the
+actual project by sawing out the port for the keyboard connector from
+the PCB because the connector is not compatible with the usual jumper
+spacings.
+
+#+DOWNLOADED: screenshot @ 2021-08-27 18:42:56
+[[file:static/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-42-55_screenshot.png]]
+
+Then I soldered jumper cables to one side of the connector (a real
+hack job :P) and done was my not-too-fragile interface which I
+promptly connected to an Arduino Nano clone I had to spare.
+
+#+DOWNLOADED: screenshot @ 2021-08-27 18:47:12
+[[file:static/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-47-12_screenshot.png]]
+
+And finally the nasty hardware part was done and I could begin to
+prototype the software on the Nano while waiting for a Pro Micro with
+native USB capabilities to arrive. It suffices to say that it worked
+:) with key velocity and all. After the Pro Micro arrived I even got
+the sustain pedal to work :).
+
+#+CAPTION: The final assembly.
+#+DOWNLOADED: screenshot @ 2021-08-27 18:51:45
+[[file:static/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-51-45_screenshot.png]]
+
+With the Pro Micro set up I went on to calibrate the key sensitivity
+which was less of a hassle than I thought and the project was
+finished. Happily I went back to making music ever after.
+
+The end.
+
+Of course there remains some cleanup to be done (datatypes in the
+source code). Most urgently I want to implement release velocity.
+You can find the code and my personal documentation for the
+project[fn::In the file named =project.org=]
+over on [[https://github.com/vale981/KSP-30_Hack/][GitHub]].
+
+Maybe this was of interest you. If not, then thanks for reading this
+far anyways :P.
 ** Uncategorized                                            :@Uncategorized:
 *** Neuseeland Restauration
 CLOSED: [2021-08-03 Tue 14:53]
@@ -2813,7 +2918,6 @@ Ein wenig python verwandelte das Ganze in das neue Blog format.
 
 Und damit koennt ihr nun unter [[/categories/neuseeland][Neuseeland]] die alten posts lesen.
 [fn:5] =ctime=, creation time
-
 * Local Vars
 # Local Variables:
 # eval: (org-hugo-auto-export-mode)

site/content/posts/converting-a-kawai-ksp-30-to-pure-midi.md

@@ -0,0 +1,93 @@
++++
+title = "Converting a Kawai KSP-30 to pure MIDI"
+author = ["Valentin Boettcher"]
+date = 2021-08-27T21:57:00+02:00
+categories = ["Hacks"]
+draft = false
++++
+
+My Kawai KSP-30 digital piano has been on its last leg for some time
+now. To get it to work at all, I had to unplug the amplification
+circuit whose interface on the main PCB was burnt out. Of course is
+wasn't of much use by itself after that bit of crude surgery but
+worked fine as a midi keyboard.
+
+{{< figure src="/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-05-08_screenshot.png" >}}
+
+There must have been some creeping currents because the piano got more
+and more unreliable requiring hectic powercycling to boot and finally
+not booting at all. Looking for spare parts on eBay didn't bring up
+anything so I decided to scan the keyboard directly with a
+micro-controller and do away with the rest of the innerts of my trusty
+Kawai entirely.
+
+First I had to find out how the keyboard matrix was scanned. Luckily I
+had a logic analyzer lying around to test the ports on the keyboard
+connector&nbsp;[^fn:1]
+
+{{< figure src="/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-15-55_screenshot.png" >}}
+
+Furthermore, I found the service manual for the KSP on `archive.org`
+and with a little trial and error was able to puzzle it together.
+
+{{< figure src="/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-26-41_screenshot.png" >}}
+
+The keyboard matrix has eight columns that can be read through `KD0`
+through `KD7`&nbsp;[^fn:2]. To scan all 88 keys three multiplexers
+are employed that can be enabled individually by the `SA4` and `SA6`
+ports (see figure above). The other three `SAX` connectors select one
+of eight rows through the currently enabled multiplexer. Because the
+piano is velocity sensitive, each key actually has two sensors with
+one triggered shortly before the other. The time difference between
+these signals can be measured to obtain the key velocity. Therefore
+the `KDX` ports are split into two groups `S1` and `S2` that
+correspond to the two triggers.
+
+{{< figure src="/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-35-47_screenshot.png" >}}
+
+Putting all this together one arrives at the following matrix.
+
+{{< figure src="/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-37-23_screenshot.png" >}}
+
+In practice one just cycles through the multiplexers while running a
+counter to obtain the correct note because they are consecutive.
+
+Having ascertained all this knowledge I began the realization of the
+actual project by sawing out the port for the keyboard connector from
+the PCB because the connector is not compatible with the usual jumper
+spacings.
+
+{{< figure src="/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-42-55_screenshot.png" >}}
+
+Then I soldered jumper cables to one side of the connector (a real
+hack job :P) and done was my not-too-fragile interface which I
+promptly connected to an Arduino Nano clone I had to spare.
+
+{{< figure src="/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-47-12_screenshot.png" >}}
+
+And finally the nasty hardware part was done and I could begin to
+prototype the software on the Nano while waiting for a Pro Micro with
+native USB capabilities to arrive. It suffices to say that it worked
+:) with key velocity and all. After the Pro Micro arrived I even got
+the sustain pedal to work :).
+
+{{< figure src="/images/Converting_a_Kawai_KSP-30_to_pure_MIDI/2021-08-27_18-51-45_screenshot.png" >}}
+
+With the Pro Micro set up I went on to calibrate the key sensitivity
+which was less of a hassle than I thought and the project was
+finished. Happily I went back to making music ever after.
+
+The end.
+
+Of course there remains some cleanup to be done (datatypes in the
+source code). Most urgently I want to implement release velocity.
+You can find the code and my personal documentation for the
+project[^fn:3]
+over on [GitHub](https://github.com/vale981/KSP-30%5FHack/).
+
+Maybe this was of interest you. If not, then thanks for reading this
+far anyways :P.
+
+[^fn:1]: Before I remembered having a logic analyzer however, I fried my Raspberry Pi with the 5V logic :P.
+[^fn:2]: Annoyingly the KDX numbers are shifted by one at other places in the manual
+[^fn:3]: In the file named `project.org`