little-scale wrote:

The audio is not formatted at all - it's just an analog audio signal smile

In terms of signal conditioning, I've had to 1) Be careful about the range of voltages that I send in 2) Add compression, limiting and multiband compression to my audio output chain that is being sent to the Atari 2600 to squeeze the best out of the four bits...

WOW, are you pushing an analog sig into the Teensy's ADC? Or are we talking processing within M4L(?) sent to tha a26 in 4 bits?? Or is there  some special Little Scale magic in the 6502 kernel, using the Joyport's paddle tricks???
This is epic.

Nah, it's the simplest thing possible

Teensy ADC --> Joystick ports --> 6502 --> TIA

little-scale wrote:

Nah, it's the simplest thing possible

Teensy ADC --> Joystick ports --> 6502 --> TIA

Ooo K, Very Cool! (seem like I'm always saying 'cool' when you post:) )

Dynamite stuff!  Great work.

Here's another taste of what's coming in the next update:

http://little-scale.blogspot.com.au/201 … voice.html

"This is a demonstration of a custom waveform channel that can be used - to some degree - to overcome some of the limitations imposed on the Atari 2600 sound chip. The custom waveform is user-defineable and can be changed during runtime.

The custom waveform also allows for a much wider range of frequencies. Additionally, the custom waveform can be used at the same time as the main two oscillators, thereby - with some clever sequencing - giving rise to three-voice polyphony."

This is all great stuff!  I had started to port this to arduino, but it involved removing the guitar sample to make enough space for the code.  At first not a big deal, but with you adding extra features so quickly I'm not going to bother any more as I dont want to have to lose features because the arduino has limited code space.  So I bit the bullet and bought 5 teensy 2 boards, so I can build this asap and not have to wait the next time you have an awesome project I want to build.

I'm assuming this works with all versions of the 2600?  The 2600 jr is smaller and generally cheaper, and space is getting to be a real issue here.  Although nothing looks better than an original 'woody' the jr would be super portable.   I'm planning on modding mine so the midi interface is in the case, and I havent tried it yet but is should be possible to make the atari battery powered.  There is a 7805 regulator in there so you should be able to hook up a 9v battery holder in the case.

If it's a 7805, you could use 4 x 1.2V NiMH batteries or some sort of rechargeable situation, no? It would feel like a waste if it's a 9V battery --> 7805 --> 5V output if it can be avoided.

Porting to Arduino should be easy, and I will do so myself unless someone else is super keen once it's at A26F v101 or 102.

Just saves time smile

sadly no.  a 6x AA battery pack would work though.  78xx regulators require approx 2 more volts at the input than their output voltage to function properly.  They usually work for a while with fresh alkaline AAs, but rechargeables have a surprisingly wide voltage fluctuation, you probably wont get 7+ volts for very long.  But I have rechargeable 9v batteries anyway, and it would be just as easy to hook up an external battery pack with a suitable jack on it..  It was more for the aesthetic as I like the idea of a portable 2600 synth with all the hardware contained in the case.

As for the arduino porting I'm not super keen I can wait.  I just prefer to program a chip on a dev board and place it with a resonator and regulated supply, it seems a bit of a waste to use up a new dev board for every project.  ATMEL's generous free samples might have something to do with it too ;-)

I hear ya re: barebones micro setup with the hardware, especially for internal mods n stuff

Sorry I meant, 4 x 1.2V or 3 x 1.5V --> the 5V output pin of the 7805, by passing the regulator altogether? Unless the higher voltage is needed elsewhere in the circuit?

Presumably its just to ensure the processors got a stable supply, which would probably cope without. Not much point me removing it if im putting an arduino in as that needs 5v regulated anyway

analog monster wrote:

sadly no.  a 6x AA battery pack would work though.  78xx regulators require approx 2 more volts at the input than their output voltage to function properly.  They usually work for a while with fresh alkaline AAs, but rechargeables have a surprisingly wide voltage fluctuation, you probably wont get 7+ volts for very long.  But I have rechargeable 9v batteries anyway, and it would be just as easy to hook up an external battery pack with a suitable jack on it..  It was more for the aesthetic as I like the idea of a portable 2600 synth with all the hardware contained in the case.

Very interesting idea. As far as battery packs, you might look into re-porpoising cordless drill battery packs. Could even reuse the handle parts to allow quick change. I bet with a 12V pack you would have Days oi run time. This reminds me of BenHeck's case mods, handheld A2600s.

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Amazing, Seb! I just found my 2600 some days ago! smile

On another tangent, Little Scale, it occurs to me that using the ADCs, one could add expression pedals, pitch and mod wheels?!?!?

Keep posting demos! Sounds great.

On another tangent, could i suggest you modify the blog post to inform people you dont need to butcher 2 controllers, as the thought of good controllers being damged makes me wince. You can buy female db9 to female db9 (rs232 serial) cables for £1.50 on ebay that you could cut in half. I think you would need to do the pin labelling for each side seperately as some pins will swap within the cable.

Ive opened my 2600 jr up and there is plenty of space inside for extra pcbs once you remove the metal shielding under the external plastic case-ive had no problems leaving this off permanently. There is also plenty of space for adding the extra jacks youll want for prosound and midi. I plan on wiring directly to the motherboard instead of splicing controllers and adding a power toggle for the teensy/arduino so i can power it off and use normal controllers for gaming still.

Also curious if a few glitched graphics could be triggered along with notes, or will that raise the noise floor coming from the chip?
It would be cool to have a little of the raw bit video along with the raw bit sound.
Encouraged to watch progress.