MidiALF!


#481

@altitude
I always cut a frame from 3mm plexi that leaves space for all things on the PCB that are higher than 5mm (Pots, Chips etc…) and glue this to the 1,6mm 2Ply Top. This way you have a sturdy Panel with all the benefits of a nice engraving….


#482

@altitude – “What would it take to add an analog clock in?”

One way to do this would be to use I2C port expander, for example MCP23008, adding it to hacking area on MidiALF/CV board. I2C bus is available on CV board if you connect it using 6x2 pin header. You will also need to add input port protection circuitry to shape incoming analogue clock signal into 0-5V range: two Shottky diodes with resistor and a cap (see MidiREX foot switch input schematics for an example).

Then you’ll have to add I2C port extender polling to Timer2 interrupt handler which may be a bit tricky since timing is already pretty tight there.

Another way is to use MIDI IN port pin: no need to mess with I2C and achieving great timing is trivial. You can even make it interrupt driven. You loose MIDI IN though.


#483

@fcd, Slick idea. Ponoko doesn’t do 2 ply at the US hub but Outfab in Texas does and I’ve been looking for an excuse to give them a whirl. They also charge by total area units instead of laser time which seems like a more affordable price scheme for laser cutting

@kvitekp, I like the midi in port approach, having two firmwares for midi or analog clock in seems like a reasonable comprimise


#484

@altitude – if you’re OK with loosing MIDI IN you may also use yet another approach: add ATTiny MCU that would time the analogue clock port and generate MIDI Clock events. You can also add handling for analogue Start/Stop signal that would generate MIDI Start/Stop events. Then you’ll have a single SPDT switch that would switch MidiALF MIDI IN connector from DIN5 socket to ATTiny MIDI OUT port.


#485

A Trigger to MIDI converter using a PicAxe 20x2 takes about 2hrs……


#486

yeah, thats the direction ill be looking, adding a playground to the cv board was a good idea


#487

@kvitekp
Would this little Trigger to MIDI Gadget interpolate MIDI Clock Events to full 24ppqn or could you do an “external Sync” mode where 0xF8 just means a Trigger pulse is registered and its up to the MidiALF to handle this right?

If so…… I’m in. Its not really much to do if i derive the Codebase from this:

Its just a Transistor and a 20X2 - maybe ill add a 4051 to switch the MIDI stream and some buttons as i would have plenty of free Pins on the PicAxe


#488

@fcd72 – me thinks that Trigger2MIDI front end should be dumb and leave clock division handling to MidiALF. Otherwise Trigger2MIDI will have to implement some sort of UI to specify division factor, which is not desirable. MidiALF already has clock divider UI, so it would handle incoming clock nicely w/o any firmware modification.


#489

@kwitekp
How about small PCB with MIDI In circuit/Trigger In Circuit a Button and 2 LEDs to indicate which mode is chosen that outputs MIDI directly to the MIDIalf MCU via flying wire or drives the Onboad Oprocoupler?
I could just route MIDI In thru the PicAxe with 0,5mS latency to get rid of a Switch….


#490

@fcd72 – sounds good! I don’t think going through another opto makes sense, midi streams from MidiALF’s on board MIDI IN circuitry and from Trigger2MIDI could be “merged” at the MCU RX port with two diodes. Of course using both ports simultaneously will not be possible, but that’s fine.


#491

@kwitekp
So all whats left ist a Trigger2MIDI thingie??? Let me check if i can do this with a smaller chip….

EDIT:
I’m pretty sure i can do this with a 08M2 Chip (tiny 8 Pin) + a simple Transistor Inverter…… wheres a free Breadboad?


#492

Loving the radioactive fish on the midi trigger converter.


#493

I now designed the serial Output of the Trigger2MidiALF Converter to be MIDI compliant so you can route it with a Diode to the Input of the Optocoupler.

As the 20pin 20X2 is just 2€ more than the initial projected 08M2 Chip i will go for these, especially because i have then much faster Hardware Interrupt that can bring down lag to about half a ms instead of 1,7ms for the 08M2.

Nice thing is i have an addition Trigger input left - what should it be used for? Options are Run/Stop on trigger pulse, Run on Trigger high/Stop on trigger low, both with LED Indicator.

Another question is shall i implement a small 7905 PSU or will we just draw power from the +5V Rail of the MidiALF?

And where should the 2 extra jacks go to?


#494

I love that Blinky the Fish panel. I must have it…


#495

I guess id get sincere problems with Untied Labels here in germany….


#496

I say just run it off the +5 vreg, its already routed to the playground.


#497

…have it made it two pieces by two different manufacturers!

Plus, Blinky belongs to us all (*killed by Fox Corporation sniper fire)


#498

It would be nice if such things were less uptight, but that’s not in the cards. You have to keep such stuff on the down low.


#499

You know Frank, now that I think about it, you’ve got a pretty hot number there… A simple uC circuit that will take an analog clock/analog start/stop and convert to midi? Probably a small audience for this but a REALLY useful device IMHO. I would base it on Roland’s dinsync, that way you can make the midi in a dual purpose connector since s/s and clock are on pins 3 and 1 which are not even used with midi. Some diodes to isolate the ground would be a good idea. A clever implementation of a midi connector after 40 years would be nice.


#500

Heres the Firmware for the “simple” 08M2 Version… its really complicated and absolutely hides the magic of the Simplicity coding with PicAxe