Posts by little-scale (Page 3) - Forums

33 Reply by little-scale May 23, 2013 5:01 am

Re: [SEGA MD / GEN] GenMDM SEGA Genesis / Mega Drive MIDI Interface (1,383 replies, posted in Sega)

Hi RyuX,
I've tested your unit out with both USB and DIN MIDI connections, so I am confident that it *can* work.

Now, did you set the jumper on the GenMDM? If so, did you unplug the USB before doing so? And if so, once you connect the GenMDM to the SEGA (without USB but with the jumper) do you find that the sound comes on?

Cheers,

- Seb

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34 Reply by little-scale May 20, 2013 11:49 am

Re: [SEGA MD / GEN] GenMDM SEGA Genesis / Mega Drive MIDI Interface (1,383 replies, posted in Sega)

Speaking of time, I'm really looking forward to having some time to add the CSM stuff to GenMDM!

Go to forum: Sega Go to topic: [SEGA MD / GEN] GenMDM SEGA Genesis / Mega Drive MIDI Interface Go to post 34

35 Reply by little-scale May 20, 2013 5:08 am

Re: [SEGA MD / GEN] GenMDM SEGA Genesis / Mega Drive MIDI Interface (1,383 replies, posted in Sega)

Oh, I've already fixed the issue - I was shifting left by one too many bits, that's all! Just a typo

Yes, I know the bug you mean and actually I don't think of it as a bug at all but rather a feature to be used creatively... which I have done with some of my releases.

One man's trash is another man's treasure etc.

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36 Reply by little-scale May 20, 2013 2:30 am

Re: [SEGA MD / GEN] GenMDM SEGA Genesis / Mega Drive MIDI Interface (1,383 replies, posted in Sega)

Ah yes - the secondary decay rate is my mistake, I have fixed it now and it will be included with genmdm 103.

This will also be updated in the editors and in the docs.

Thanks for pointing this out! My apologies.

Go to forum: Sega Go to topic: [SEGA MD / GEN] GenMDM SEGA Genesis / Mega Drive MIDI Interface Go to post 36

37 Reply by little-scale May 20, 2013 2:28 am

Re: [SEGA MD / GEN] GenMDM SEGA Genesis / Mega Drive MIDI Interface (1,383 replies, posted in Sega)

The mute does not actually mute - i mean, the low level output is normal, at least with all hardware i have tested with.

I will look at the code for the secondary decay rate now!

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38 Reply by little-scale May 18, 2013 8:53 am

Re: [SEGA MD / GEN] GenMDM SEGA Genesis / Mega Drive MIDI Interface (1,383 replies, posted in Sega)

Yes, I have such a thing planned.

There are two ROM arrays that store sample data:

The first stores the actual samples as one long, 8 bit unsigned list

The second stores the length of each individual sound in samples, so as to be able to read as offsets into the long sample array and retrieve each sound separately.

Would it be of use for me to find these two arrays in the binary?

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39 Reply by little-scale May 11, 2013 12:51 pm

Re: LITTLE-SCALE SN76489 USB MIDI (53 replies, posted in Sega)

Samsung Galaxy S4 controlling SN76489 via MIDI directly:

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40 Reply by little-scale May 11, 2013 1:30 am

Re: Rechargeable DMG (Mods to be potentially added update) (36 replies, posted in Nintendo Handhelds)

Fantastic work.

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41 Reply by little-scale May 10, 2013 6:58 am

Re: LITTLE-SCALE SN76489 USB MIDI (53 replies, posted in Sega)

I was chilling in my lunch break.

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42 Reply by little-scale May 10, 2013 2:01 am

Re: LITTLE-SCALE SN76489 USB MIDI (53 replies, posted in Sega)

Aaaaand... arduino version: http://little-scale.blogspot.com.au/201 … 1-for.html

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43 Reply by little-scale May 10, 2013 1:37 am

Re: LITTLE-SCALE SN76489 USB MIDI (53 replies, posted in Sega)

The SN76489 USB MIDI 101 firmware includes the following changes:
• Support for traditional 5 PIN DIN Plug via an optional MIDI input circuit

Download the firmware here: http://milkcrate.com.au/_other/download … DI_101.ino

This firmware update changes the circuit of the Teensy and SN76489, as follows:
NEW PINOUT

==== DATA ====
Teensy PORTB 0 = Teensy Digital Pin 0 --> SN76489 Pin 10 (Data 0)
Teensy PORTB 1 = Teensy Digital Pin 1 --> SN76489 Pin 11 (Data 1)
Teensy PORTB 2 = Teensy Digital Pin 2 --> SN76489 Pin 12 (Data 2)
Teensy PORTB 3 = Teensy Digital Pin 3 --> SN76489 Pin 13 (Data 3)
Teensy PORTB 4 = Teensy Digital Pin 13 --> SN76489 Pin 15 (Data 4)
Teensy PORTB 5 = Teensy Digital Pin 14 --> SN76489 Pin 1 (Data 5)
Teensy PORTB 6 = Teensy Digital Pin 15 --> SN76489 Pin 2 (Data 6)
Teensy PORTB 7 = Teensy Digital Pin 4 --> SN76489 Pin 3 (Data 7)

==== CONTROL AND MIDI INPUT ====
Teensy PORTD 0 = Teensy Digital Pin 5 --> SN76489 Pin 5 (Write Enable)
Teensy PORTD 2 = Teensy Digital Pin 7 --> Receive data from MIDI INPUT CIRCUIT

==== POWER AND CRYSTAL ====
Teensy Ground --> SN76489 Pin 8 (ground)
Teensy Ground --> SN76489 Pin 6 (Output Enable)
Teensy Ground --> Xtal Osc Ground
Teensy 5V --> SN76489 Pin 16
Xtal Osc Signal --> SN76489 Pin 14 (Clock)

==== AUDIO OUTPUT ====
SN76489 Pin 7 --> Audio Output Signal
SN76489 Pin 8 --> Audio Output Ground

==== MIDI INPUT CIRCUIT (ONLY IF REQUIRED) ===
MIDI Input DIN 5 Pin 4 --> 4n28 Pin 1
MIDI Input DIN 5 Pin 5 --> 4n28 Pin 2
N4148 Diode (positive anode) --> 4n28 Pin 1
N4148 Diode (negative cathode) --> 4n28 Pin 2
4n28 Pin 6 --> 100k resistor (leg 1)
100k resistor (leg 2) --> Teensy Ground
4n28 Pin 5 --> Teensy PORTD 2 = Teensy Digital Pin 7
4n28 Pin 5 --> 3.3k resistor (leg 1)
3.3k resistor (leg 1) --> Teensy 5V
4n28 pin 4 --> Teensy Ground

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