Miracle Piano Final Thougts

I finally had time to probe a few pins inside the Miracle Piano.

AS0012 - Pin 21 (PWM)
It turns out this pin controls the master volume and NOT the envelope as I had originally assumed.
Turning on the keyboard, this pin defaults to about 50%, but as you can see, it is not exactly 50%. How odd.
When the volume is reduced, the pulse width is widened and when the volume is increased, the pulse width is reduced. That is because the integrator, U4A is inverting the output.

Each photo has the scope set to 10 microseconds per division:

Default Volume:



Highest Volume:



Lowest volume:



U4 - Pin 1
This pin goes to the LM13700 to control the master volume, or gain of the sound. It appears as a DC voltage and is remarkably solid. There is no visible ripple as would be expected from an integrator.
No photo is needed of this signal.

J004 - Pins 21-24 (OUT1-OUT4)
The signals from these pins are too small to view on my scope, so I chose the amplified versions from U10. Pins 1, 8, 7 and 14 respectively.

OUT1 is not active for all sound samples, apparently. When Harpsichord and Synthesizer are selected, nothing comes out at all.
When the other four sounds are selected however, the waveform is perfectly clear.

OUT2 is the opposite. Only when Harpsichord and Synth are selected, do we see any activity on this pin.

OUT3 mimics OUT1 exactly, or at least as far as I can tell.

OUT4 on the other hand does not seem to react to any button or key. It simply outputs a DC voltage which measures 5.03v at pin 14 of U10.

I can speculate as to why there are three OUT pins. While probing both Pins 8 and 14 of U4 which has the mixed and filtered outputs split to both left and right output terminals, the waveforms are identical for Harpsichord and Synthesizer but are not identical for the other four sounds. It would seem that Harpsichord and Synthesizer were recorded and digitized in mono while the other four sounds were recorded and digitized in stereo.

I am a little saddened that the envelope is not broken out to any specific pin or sub-circuit.

Some other Notes

J004 - Pin 40 (Bus Strobe)
This pin reacts differently for different sounds, however, when the key is pressed with a sound that has an attack and release; the pin will strobe for the full length of the sound and go to 0 when the note is finished.
For a sound that ends only when the key is released, the pin strobes at key press for a moment, then goes to 0 and strobes once again when the note is released.

I could use this pin for creating a gate and trigger, but it would require that I charge a capacitor then feed it through a comparator and set up some logic to keep the signal high when the key is pressed and low when the key is released. This wouldn't require too much effort, but the function would change from sample to sample since the envelopes are all different. I don't thin the modification is worth it in this case.

"Piano" sample is very hard to photograph since the amplitude changes so rapidly in software. It looks very similar to "Organ, but is more rounded whereas the Organ is more triangular.


"Organ:"



This photo shows a sample that is identical on both sound channels. Trust me, they are identical but the channels are not being displayed the same way.


These two photos show sounds that are not identical from OUT1 and OUT2.



PS: Yes, the reflection in my oscope is naked. Deal with it.

Fun with the Sega Genesis - Ultimate Portable Game player

Found a crazy deal on fleabay for one of these and had to have it. I had heard stories of how badly they are made, and how miserable the audio is.
All very true, but I think it can be improved a little.

The video is great, the size a too small, the sound from the speaker is crap but the sound from the headphone could be worse.
I immediately took it apart after opening the box. I was THRILLED to see only one epoxy-chip and several SOP's! :D

I want to believe that the audio issue is because of the amp/filter they have used. Through headphones, it sounds ok, but also a little clipped and shallow. This could also be because of the power supply, which is very weak. The battery is 3.7v and droops when the PSG is loud.




Its like a portable MP3 player considering all the titles that have sound tests. :p
You know, except horrible sounding.

Do not stay at the Guest Quarters Hotels - Dumping The Miracle Piano Teaching System

I had my Willem programmer pulled out for some Sega Genesis programming stuff and decided to finally dump the eprom inside of the Miracle Piano teaching System Keyboard. If you recall from a previous post of mine, it contained a 27c256 OTP eprom. It also contained many proprietary ICs of which I may never figure out. We may never know what microcontroller they used or what language the machine code is suppose to be written in. z80, 6502, etc.

In any case; with many vintage computers and other devices containing ROM, the authors always find the space to sign and date their work and in rare cases they may even decide to add a little easter egg. Although I cannot locate a date, here is some clear text I found in the ROM image:

"This Eprom contains code created by Mike Collins. Anne Graham and Ray Livingston. Do not stay at the Guest Quarters Hotels. Keep that Coke classic and that Piping hot coffee coming."



I got a real kick out of reading that. For anyone who knows what to do with it, here is the binary file:
http://www.mediafire.com/download/eo3zujca7jvw44f/MPTS_ROM.zip

Populating the GB-Programmer (Jazz-Assembly #1)

The board has been designed to accommodate different methods of programming the Atmega8515 (hereby simply called 8515). Once programmed, you may never choose to reprogram it again because there may never be updates to the firmware anytime in the future.

Step 0.
Admire your beautiful new toy. 

It shall prove to be very useful regardless of your individual purposes. Also, at no time should you power your board until I say so.

Step 1.
Soldering both SMT ICs

The picture below is of two board prior to me cutting them apart. To reduce cost, I panelized my design.




You may choose to solder one IC at a time or both at once depending on your skill and resources. It would be highly suggested to use either a hot air gun or some type of oven and solder paste. Soldering by iron is perfectly possible, but creates more chance for failure. If you are a frequent reader, you should know that I now own an awesome hot air station, so I also bought a tube of solder paste.

Simply apply a very small amount of solder paste to the bare pads and carefully place your IC over top of them. Make sure that it is aligned as closely as possible, not forgetting to orient pin 1 in the right direction. Pin 1 is designated by the white circle on the board.





Once you finish both ICs, make sure that there are no shorts in places that they may not be. If you find one, attempt to draw the solder off of the pins with your iron or solder wick. Check it again and once satisfied, move on.

Step 2.
Through-hole components.

As much as I had hoped not to use any through-hole components, my audience insisted. The through-hole components required include:

2x 0.1uF ceramic capacitors (may be labelled 104)
1x 4.7uF electrolytic capacitor
1x 10K ohm resistor
1x 1K ohm resistor
2x 220 ohm resistors
2x LEDs (two colors)
1x female USB type B connector
1x gameboy cartridge connector

For the time being, do not populate C4, R6 and R7. These are not relevant at this time. You may choose to use a 6MHz ceramic oscillator, but I suggest saving the money and moving on. If you do though, cut the trace leading from it to the FDTI chip.

Start by placing the leads into the holes and bending them away from center so that they stay in place. Sodler each component on the underside and clip the legs at the board. Some people would suggest to clip them before soldering though.

Also make sure that the electrolytic capacitor (C3) faces negative lead down as shown below. Each components has the appropriate value marked on the board, so you cannot go wrong. Seating the gameboy cartridge connector may be the most difficult through-hole component. It has the most pins and each of these pins could be slightly bent from originally removing it. Take your time and do not stress.



The LEDs can be any color you like, but know that the one farthest from the resistor is power and the other one is activity. I prefer my toys to have a green power LEd. ;)




Step 3. 
PC Connection

Check your SMT soldering ONE MORE TIME. If and only if there are no shorts between pins, connect the board to your PC and cross your fingers... IF all is well, the LED should light up and a driver should automatically install for your device. It will also be given a COM port number.




Step 4.
Programming the FT232RL and 8515

Thats right, you're going to program both ICs. There is only one modification that needs to be made to the FT232RL (hereby simply called 232) which is to make it output a 6 MHz clock rate. This is for the 8515 to run on.

First, the 232's internal eeprom must be modified. To do this, we will use FT_Prog found on the FTDI website here:
http://www.ftdichip.com/Support/Utilities.htm#FT_Prog

Only one modification must be made and that is to change the CBUS0 pin to act as a 6 MHz clock. We will not worry about the other pins because they are all unconnected. CBUS0 is one of five programmable I/O pins and there are many options to choose from, but I am not going to cover these here.

Install FT_Prog and run it. You'll be greeted by a well designed GUI ... just don't touch anything. plug in your device and it should install a driver if it has not already. Once "Your device is ready to use" go ahead and click "Scan and Parse" which looks like a magnifying glass. Your device should pop up in the dialog box under device tree like this:



You can see that your device is already programmed, but we must now change one function. Expand the device tree as such:
FT EEPROM -> Device Specific -> IO Controls -> C0
Use the drop-down to select CLK6 in the C0 bus only. The other pins are all useless as they are not connected to anything. Ignore them.



Click on the lightning bolt which is the program button, make sure your device is selected and press "program" if and only if you are positive you did not change any other settings.
The bottom of the window will say finished and then ready. Close the window and close FT_Prog, then disconnect your programmer.



Reconnect your device once more and it should install the drivers again and give it a new COM port. You can now move on, but if you were to open your device in FT_Prog again, you would notice that C0 is still set to CLK6. Good job!

Just a note, but the reason you should not touch any other options in the eeprom settings is because there are too many settings that can be set incorrectly. For example, if you were to program your device to use an external oscillator, it would be rendered useless and you spent a lot of time and energy soldering that chip perfectly! So be careful!

Step 5.
Programming the 8515.

The easiest way to program the 8515 is via FTDI BitBang. It is a totally new concept to me, but incredibly useful considering how much people want to charge for ordinary ICSP programming kits. It may be a tad bit slower at programming, but since you will only program the 8515 once, it does not matter.

I put together a file-pack to get you started. This pack  includes AVR_DUDE, my custom config file special for this programmer and the hex file which needs programmed to your 8515. I am writing the guide on the GUI version of AVR-DUDE. Everything is easier with a GUI, though you have to show a little love for the tried and true command prompt. ;)

Download it here:
http://www.noisechannel.org/wp-content/uploads/2013/09/GB-Progger-kit.zip

Lets get started.

Go ahead and hook up your programmer if it is not already. Open avrdude-GUI.exe.
1. Direct the first box to your avrdude.exe
In our case, we will be using the avrdude-serjtag that you downloaded.
2. Pull down the "Programmer" Box and select the "FT232R Synchronous BitBang for Jazz (GBProgger)."
3. Leave the port drop box blank.
4. Locate "ATmega8515 (m8515)" under the "Device" drop-down.
5. Type "-P ft0 -B 4800" in the "Command line Option" box. It should look just like this below:




6. Click the "Read" button under Fuse. This will show you the fuse bits on your 8515 which must be changed. It does not matter what they are now.




7. Change the fuse bits to C910 as pictured and hit write. It will be very fast and just ask you if it went well.




8. Now erase "-B 4800" from the "Command line Option" and browse for the hex file under Flash then hit write. It is also fast, too fast for me to get a screenshot even.




9. Exit and done. Disconnect your device and reconnect it. If all went as planned, you now own a GB Programmer and Dumper for whatever needs you may have.

Lets test it out, shall we? That is another blog post, for another time. See you then! :D

 Cheers,
Jazz

A New Soldering Station and a New Confidence

I SPENT REAL MONEY!

 Being as underemployed as I am it is very hard to allocate funds such as this, but I threw 80 bucks at a new soldering station because this is no longer a hobby. I may only make a little here and there, but soldering and designing electronics is now a profitable experience.

I thought to myself "If I wish to further my abilities, then I had better stop limiting myself with this horrid Radio Shack iron..." So I did. :)

I researched and asked and polled for the best station under $80 and the 'nearly' unanimous response was the Kada (or similar) 852D+ 2-in-1 SMD rework station. The one I picked up is by XPower, but it uses the same iron and case as other clones; it probably even has the same 'stolen' program as Kada's.

So far, my experience has been very positive. I haven't given it any extensive use as of yet, but my Gameboy Programmer Boards will be arriving soon! If you've read that post, they have some surface mounted IC's and I am just dying to try out my new hot air gun! I have watched a few videos on how to apply SMT chips and components with a hot air gun and solder paste. It seems as simple as if I were to glue them on and blow dry it!

Once the boards and parts arrive, I may make a video on the completion of one board. The video will also be a review of the station so that others may learn before they buy. (Though I suggest any self-respecting modder should) ;)

well here she is:




I REALLY need to clean off my desk...This should fit well at the back but I still have to build my solder-smoke filters to rest underneath. Those will be another post soon enough.