Digitech JamSync - How does it work?

[calde]

@Nikogo, the arduino sketch needs only the serial out and serial in.

But:

attiny85 clock is internal and I have some doubt about the stability to sync to midi signal

attiny85 has very low memory

attiny85 (I think) supports the serial communication by external library, that eats some memory

However someone could try to compile and see the size ...

[calde]

Hi,

I've tried to compile the sketch for AtTiny85, but I've got this:

Sketch uses 5414 bytes (264%) of program storage space. Maximum is 2048 bytes.
Global variables use 266 bytes (207%) of dynamic memory, leaving -138 bytes for local variables. Maximum is 128 bytes.
Sketch too big; see http://www.arduino.cc/en/Guide/Troubleshooting#size for tips on reducing it.
Error compiling for board ATtiny25/45/85.

I have added the board:
https://raw.githubusercontent.com/damel ... index.json

And I have added at top:

Code: Select all

#include <SoftwareSerial.h>
const int rx=3;
const int tx=4;
SoftwareSerial Serial(rx, tx);

I think that Attiny85 isn't suitable for this scope.

[teebee]

Finally it works, this is super cool, it opens up a whole bunch of new possibilities! I don't know exactly what was wrong in my first attempts, I guess there were a couple of concurrent things causing trouble: MIDI clock was unintentionally switched to MIDI thru on my source device, MIDI out plug was loose, and the MIDI in connectors on my arduino were swapped (well, I swapped them at one point). @calde: thanks so much for your help!

Now, to push this project a little further: I could imagine to use the jamman as a master device in some situations. How would that work?

[Nikogo]

@Teebee: The proposed Attiny85 schematics could be modified to have the MIDI style output. My initial doubts were about the internal clock stability and the program compatibility.
@Calde: Enrico, muchas gracias for your research, the code, and your advice.
I have ordered a few Arduino Nano and am impatiently waiting for a slow boat from China.
Meanwhile in a search for a compact design I found that the Nano can be placed inside the BeatBuddy under the display PCB. I would need 6 wires to connect it.
Two wires for 9V DC could be taken from the DC power connector or from the PCB (it has nice big soldering pads);
Two wires from MIDI Out could be taken from the PCB near the MIDI connector to be an input for Nano;
Two wires for the output from Nano could be connected to the two empty contacts of MIDI PS/2 connector. So the MIDI Input and Output of BeatBuddy would be still available but for connection to a JamMan I would need a special cable. I made such a cable from the old mouse PS/2 connector and the headphone cable with 3.5mm stereo plug.
I will keep the MIDI shield circuits. But I guess the optical isolator may not be even needed. Because the ground is common and the 5V DC power is the same for BB and Nano it would be enough to connect the MIDI Out from BB with a single wire to Nano's RxD and the TxD through 220 Ohm resistor to JamMan (using the 5VDC through 220 Ohm from the MIDI Out). The only doubt is if the BB MIDI out would be overloaded when the real MIDI connection is used (the Nano would be still connected inside).
Please give your opinion.

[calde]

Hi Nikogo,

I am not so expert in electronics to help you with optical isolator.

About the Midi out, I think that is safer disconnect the midi out connector of the BeatBuddy and change it in MIDI THRU. You can find schematics online.

good work!

[Nikogo]

An update for installation of Arduino Nano in BeatBuddy for synchronising with JamMan Solo XT.
The Nano is connected inside BB with 4 wires (30 AWG) and need only 2 headers (2 pins each) soldered into last holes of each row on Nano board (GND, VIN and Rx0, Tx1). The shield boars is a piece of a breadboard 18x8 mm with 2 female headers and a single 220 Ohm resistor. The GND is connected to the ground tab (-9VDC) and VIN - to +9VDC tab where the BB power connector is connected to its board.
The Rx0 Nano input is connected to the MIDI output pin on MIDI connector. If looking on left external side of BB it is the right pin in top row. The MIDI connector's bottom left pin is MIDI ground, bottom right - not connected, the middle row pins are MIDI input, the top left is +5V thru 220 Ohm resistor of MIDI output.
The Tx1 Nano output thru the 220 Ohm resistor (on shield board) should be connected to the MIDI connector's bottom right pin.
I made the synchro BB-JM cable from a headphone cable with 3.5 mm stereo jack plug and the old PC mouse connector. It connects the BB MIDI top left (+5V) pin to the ring and the bottom right BB MIDI pin (Tx1) to the tip of 3.5 plug.
Such connection allows to use the BB MIDI connector for MIDI purposes without restrictions. The BB MIDI output that I connected to Rx0 has a buffer on OpAmp follower and can easily drive two parallel ports, so the Rx0 Nano input does not affect its functionality. Between the OpAmp and the MIDI pin there is a 220 Ohm resistor. The Nano input could be taken before or after that resistor.
I wrapped Nano with Kapton tape for insulation.
And it works.
Thank you all

[Guitar Rabbit]

Hi all, I just wanted to say thanks for this great project!
It makes the Jam Man so much easier to use for looping when connected to a drum machine, in my case the iOS app "Patterning".
This was my first Arduino project and it worked with a cheap clone and a midi breakout board with the Jam Man Solo XT.

Here is a shopping list for anyone interested:

XCSOURCE® UNO R3 Rev3 Board Development Board ATmega328P CH340G AVR Arduino Compatible Board +Cable for Arduino DIY TE113 £5.99
from https://www.amazon.co.uk/dp/B00SR4FLMI/ ... 11_TE_item

5 Pin DIN Plug 5DIN-PLUG £0.44 1 £0.44
MIDI Breakout Board MIDI-BB £6.00 1 £6.00
3.5mm Stereo Jack Plug STEREOJACK £0.40 1 £0.40
from http://www.hobbytronics.co.uk/

At first I was unsure about aforementioned voltage dividers which seem to be unnecessary, it works fine without.