Dual PT2399 with tap tempo

[Marshall Arts]

http://uk-electronic.de/onlineshop/index.php?osCsid=e667159f6be43fc52b5fd9ee08751f34

This looks to be an all around good option for components, almost independent of your location. I have'nt completed an order yet, but I have a cart full that I need to go ahead and close on.

I know Uwe's shop, very reliable, I can recommend him. Did not know he had the digital pots already! Thanks for the hint!

[Jebus]

This is really interesting! I still need to get some digital pots so I can look into this Great work!

[Marshall Arts]

Planning the layout... I will reduce from three preset buttons to one, that can cycle through three user specific presets and an additional multicolor led for the presets. Everything except the 3 foot switches (tap tempo, subdivision, presets) can be pcb mounted. A 10 mm hole will give access to the USB port ;-)

[Marshall Arts]

...the nano will most likely have to go on the bottom side, given its height compared to the encoders.

[solderfumes]

Very very cool!  How much storage does the code use up on the Arduino?  Like others, I'm wondering about attempting to use an ATtiny chip or a bare uC, but the Arduino Nano looks like it would probably be just as small in the end.

[Marshall Arts]

The program uses like 26% of the nano's storage. But a lot of it is for modulation, rotary pot reading and such. I guess it would be possible to strip it down to just tap tempo - one button, one LED, that is all (besides one digital pot, some caps, an oscillator and such). Calibration might be tricky (you would need the connection for the footswitch and the LED while running the calibration program, upload the main program and than connect the footswitch and the LED).

[Marshall Arts]

Meanwhile, I am making progress with the PCB. There will be three rotary encoders (left to right: delay, mod freq, mod depth), two multicolor LEDs (left to right: preset, tempo - will change that, as the tap button will be left and the preset button will be right), three buttons (from left to right tap, subdivision, preset). Modulation on/off will be a SPDT somewhere on the left side (or even the rear of the unit) and there will be one TRS-Jack connection for +9V (left or rear), GND and of course pin6-control to my delay. It might be necessary to solder the nano in (rather than socket it), given it's height; it therefore is placed in a way, that the usb-port is accessible from the right (through a 10 mm hole in the enclosure).

The lower picture shows how the PCB will be placed in a landscape 1590B.

I am on vacation for a week and did not bring the breadboard, so I haven't programmed / tested the change from 3 preset buttons to one preset button. It will probably be a (solvable) prorgrammers nightmare to have one button and an RGB-LED (with only blue and red connected,as I ran out of pins) for cycling through and storing presets:

Storing a new setting should work like this: Press the button long: preset led starts blinking. Press the button short (once or twice) to go to the preset location (red, blue, purple(=red and blue)). Press the button long again to save it there (LED stops blinking).

[Soup39]

Gotta say,  while I don't fully grasp it all. It is cool as hell and I want one!

[Marshall Arts]

Gotta say,  while I don't fully grasp it all. It is cool as hell and I want one!

I will clarify with Brian, if a group buy is ok for him - if yes, I will sell leftovers there...

[Marshall Arts]

Even without a breadboard around, I sorted out the one-button-three-presets issue...

https://123d.circuits.io/circuits/1841053-one-button-three-presets

Start simulation (top left corner), press black button short for preset changes, press button long to change into store mode (LED blinks), select store position with short presses, press button long again to store on selected location and change back to preset mode.

[Marshall Arts]

Time to order my sample PCBs.

[Marshall Arts]

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[selfdestroyer]

Nice, I etched up a proto PCB that storyboardist made me and just waiting on one of the digital pot ICs from mouser. I got it breadboarded and tests seem to work well. This has been a fun project for sure, so far.

Cody

[Marshall Arts]

Great. I hope I get this soldered over the weekend!


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[nzCdog]

pcb looks awesome man, can't wait to hear more aout your progress