Burning a new demo mode for the Boldport Club Stringy, with a Ruby gem for MusicXML conversion to PIC assembler.
A quick video of the the new demo...
So, a long time after building the Boldport Club String, I decided to read the source .. and discovered I totally missed the fact that it has a demo mode;-)
I was reading the source to learn more about what tricks James Hutchby used to implement the Karplus-Strong algorithm, but now I am distracted and decided first to make some new demo tracks.
It's great to see source code being released, thank you Boldport and MadLabs!
I'm using MPLAB X IDE v3.51 on MacOSX.
After loading the source files in a new project CustomDemo.X, my first build failed with two errors:
Error[151] LittleArduinoProjects/BoldportClub/stringy/DemoBurner/CustomDemo.X/stringy.asm 1426 : Operand contains unresolvable labels or is too complex
Error[151] LittleArduinoProjects/BoldportClub/stringy/DemoBurner/CustomDemo.X/stringy.asm 469 : Operand contains unresolvable labels or is too complex
It seems this is to do with addressing, so I switch to absolute mode:
.. and now it builds
make -f nbproject/Makefile-default.mk SUBPROJECTS= .build-conf
make[1]: Entering directory 'LittleArduinoProjects/BoldportClub/stringy/DemoBurner/CustomDemo.X'
make -f nbproject/Makefile-default.mk dist/default/production/CustomDemo.X.production.hex
make[2]: Entering directory 'LittleArduinoProjects/BoldportClub/stringy/DemoBurner/CustomDemo.X'
"/Applications/microchip/mplabx/v3.51/mpasmx/mpasmx" -q -p12f1840 -u \"LittleArduinoProjects/BoldportClub/stringy/DemoBurner/CustomDemo.X/stringy.asm\"
"/Applications/microchip/mplabx/v3.51/mpasmx/mplink" -p12f1840 -w -m"dist/default/production/CustomDemo.X.production.map" -z__MPLAB_BUILD=1 -odist/default/production/CustomDemo.X.production.cof build/default/production/stringy.o
MPLINK 5.08, LINKER
Device Database Version 1.34
Copyright (c) 1998-2011 Microchip Technology Inc.
Errors : 0
MP2HEX 5.08, COFF to HEX File Converter
Copyright (c) 1998-2011 Microchip Technology Inc.
Errors : 0
make[2]: Leaving directory 'LittleArduinoProjects/BoldportClub/stringy/DemoBurner/CustomDemo.X'
make[1]: Leaving directory 'LittleArduinoProjects/BoldportClub/stringy/DemoBurner/CustomDemo.X'
BUILD SUCCESSFUL (total time: 880ms)
Loading code from LittleArduinoProjects/BoldportClub/stringy/DemoBurner/CustomDemo.X/dist/default/production/CustomDemo.X.production.hex...
Loading completed
The stringy board has pin sockets for all the PIC pins (even in the same order as exposed from a programmer), so I'm guessing I can program this in-circuit?
| Programmer Port | PIC Pin | Encumberances? |
|---|---|---|
| 1: VPP | 4 MCLR | Normally-open S1. OK |
| 2: VDD | 1 VDD | Battery and regulator, OK if battery not attached |
| 3: GND | 8 GND | Battery OK if battery not attached |
| 4: PGD | 7 RA0/ICSPDAT | 1kΩ pull-down resistor. Hmm, should be OK? |
| 5: PGC | 6 RA1/ICSPCLK | 1MΩ pull-down resistor and "plectrum" leads. Make sure plectrums are safely isolated during programming |
Here's a PICkit 3 connected to the stringy, with some blu tack assist:
Connecting up the programmer, and I'm seeing the device OK..
And it programs without error..
*****************************************************
Connecting to MPLAB PICkit 3...
Currently loaded firmware on PICkit 3
Firmware Suite Version.....01.46.14
Firmware type..............Enhanced Midrange
Programmer to target power is enabled - VDD = 4.750000 volts.
Target device PIC12F1840 found.
Device ID Revision = 5
Device Erased...
Programming...
The following memory area(s) will be programmed:
program memory: start address = 0x0, end address = 0x49f
configuration memory
User Id Memory
Programming/Verify complete
Note that I've enabled powering the device, so I can test it without having to install a battery. Out of habit, I set the voltage at 4.75V instead of 5V, as the PICkit 3 is prone to errors otherwise.
Power up the stringy, and it works just fine. So far so good!
So the final thing I want to do for now is burn new demo track.
.. but I don't want to be transcribing/composing in assembler, so instead I "assembled" this workflow:
- score in Guitar Pro
- export to MusicXML
- convert to assembler for the stringy with a Ruby gem StringyFi
- compile with MPLAB X IDE
- program the stringy using a PICkit 3
Olé!
See the music sources in examples - *.gp is the Guitar Pro file, *.xml is the MusicXML export.
My first attempts were with some quite complex scores and I immediately ran into the major problem: the current stringy code only allows for 2-bits worth of note duration, which doesn't cut it for anything ranging from half notes to 32nd's, with dotted notes and ties!
So I limited myself and found a nice (appropriately named) candidate - the main riff from Deep Purple's Burn. I still had to simplify the transcription somewhat to encourage the stringy to play it decently, and I think the result is "OK" .. see it on YouTube.
Here's the simplified score:
I clobbered together some routines I'd used before into a simple converter packaged as the Ruby gem stringyfi.
It has to make a whole lot of assumptions like: only covert 1 part, 1 voice, and choose the closest duration.
It currently pays no attemption to original tempo, and doesn't support many notation features (such as tied notes).
There's a Gemfile waiting to install in this directory. Assuming you have a working Ruby environment:
$ gem install bundler # if not already installed
$ bundle install
Choose the XML to convert, and pipe the output into the demo.tun file
$ stringyfi ./examples/BurnIntro.xml > ./CustomDemo.X/demo.tun
converting ./examples/BurnIntro.xml..
shortest_fractional_duration: 0.125
octave_range: [3, 5]
.. done.
Now just recompile the CustomDemo.X project with MPLAB and program. Here's BURN getting burned:
*****************************************************
Connecting to MPLAB PICkit 3...
Currently loaded firmware on PICkit 3
Firmware Suite Version.....01.46.14
Firmware type..............Enhanced Midrange
Programmer to target power is enabled - VDD = 4.750000 volts.
Target device PIC12F1840 found.
Device ID Revision = 5
Device Erased...
Programming...
The following memory area(s) will be programmed:
program memory: start address = 0x0, end address = 0x49f
configuration memory
User Id Memory
Programming/Verify complete
The freshen_source.sh script grabs the original sources files (including the original demo) and replaces the sources in CustomDemo.X project.
Useful to:
- put the original demo tune back in place
- undo any modifications to the firmware and revert to "factory" mode
After investigating the original source, I've seen a few areas that might be worth working on:
- finer-grained duration control. 2 bits isn't enough for more complex scores
- running longer tracks. When I tried longer pieces, I suspect I ran into memory addressing limits or possibly timing bugs - not sure which yet, but 20 odd measures in, the stringy would go haywire.
- LEAP#323 stringy - my original stringy build and project info
- StringyFi - source for the MusicXML conversion gem
- Original String Source
- MPLAB X IDE
- Guitar Pro
- ..as mentioned on my blog