Brain transplant! De-BOSS-ing a ME-70 with a Teensy 4.0

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Had too much time today and so I decided to cannibalize a braindead ME-70 I had already thrown into the junk box, because the 'customer service' at Roland prefers to p on users and charge 150 Euros plus shipping to reflash a faulty-by-factory firmware, which can not recover from a power outage that happens just while moving a potentiometer. Not again. I tracked down the Service Notes on the net, but no chance to reanimate the thing without reverse-engineering the firmware.

So I came to the idea of replacing a 11 year old ESC chip with a Tensy 4.0, which I guess would anyway dance circles around the oldie.

The board is better than one would expect:

AK4556VT codec (!)
nice preamp NJM2115V
nice power supply around a BD9850FVM
stereo headphone out with insert detection
stereo line out with mute circuit
6 detent pots and
19 smooth pots on muxes
1 analog foot pedal
4 footswitches
2 switch inputs
5 pushbuttons
14 LEDs and
2-digit-LED display on serial latches

I added some features:

Teensy 4.0 with USB, obviously
a MC34063A and stuff in app note config to provide 9V from USB and limit inrush/charge current to the board's many caps and filters
S-PDIF optical out
a 240x240 IPS with ST7789 over SPI, just because it is cool
two CD74HC4051 muxes to compensate missing inputs for Teensy 4.0 ;)

wires, more wires,
damping resistors (!) on all digital lines
glue to hold it all together

After the patchwire orgy, it just plays extremely well and now I have something to play on with Audio library.

More will follow, if you are interested.
My primary intention was to build a Teensy 4 stomp box pedal from scratch, but this is way cooler for now. The stomp box will follow once the software is complete.
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The ME-25 is a different device, so if you want to hack into that, you'll have to reverse-engineer that first, or find the "service notes" as Roland calls them or the service manual, as such papers are more commonly called.
 
Yes thanks I know that it is a much less capable device than your ME-70 which is why I am interested in what you have done with yours - it will be a more efficient approach than reverse engineering another Boss Guitar pedal.

Just taking a wild guess here - you would not have one of the Marshall Code 50 or 100 series amplifiers as well?
 
If your ME-25 is working, then leave it so.
My ME-70 was FUBAR, see inital post.

Now I've rebuilt all the functions of the original, plus another much better wah, on the Teensy 4.0 and still use less than 14% of CPU time if all is enabled. But the Audio Library just sounds a bit too dirty after some stages of effects, due to 16 bit. So I will rewrite the objects I need with more precision. I am just digging through this. Stay tuned for more.
 
Ah, just for the amp: I have built a 4xEL34 valve top from scratch, with some ECC92's in the FX section, etc. Something that is really NOT digital.
btw: the Marshall of a band member just vomited his cone as he tried to keep pace...
 
Deleted User said:
If your ME-25 is working, then leave it so.
My ME-70 was FUBAR, see inital post.

Now I've rebuilt all the functions of the original, plus another much better wah, on the Teensy 4.0 and still use less than 14% of CPU time if all is enabled. But the Audio Library just sounds a bit too dirty after some stages of effects, due to 16 bit. So I will rewrite the objects I need with more precision. I am just digging through this. Stay tuned for more.
Click to expand...

Staying tuned - Class D changed my long-held strong disposition for even-order second harmonic distortion amplifiers forever...
 
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