LPT to MIDI interface (first build, v.1.0.0.0)

[Jidis]

I was surprised he did what he did on a 16F84. :)

I always figured that was for smaller stuff. Still wondering about the half duplex thing though. ???

[buhler]

Is this still going strong?  any new developments?  i think i'm going to build one of these but i'm curious how Jidis is doing with his pcb. ;D

[Jidis]

Oh hey Buhler :)

Yeah, I've had mine a while, but didn't have much luck with it. I mailed Plog a couple weeks ago, but haven't heard anything and didn't want to bug him. From what I can remember of it, I was able to get certain signals coming off of it, but the output wasn't 100% solid, like I'd get pieces of controller messages while outputting notes and stuff, and I could send MIDI clock from it, but not MTC, etc.

I didn't see the input work, but my circuit was a bit of a "mod" and I haven't had the chance to try to strip it down and see if any of the extra stuff was responsible. I also used a 16F819 chip (which Plog said was OK), but it seemed to compile OK with a change or two to some labels or something that were named differently. Main difference with mine was just that I used the two MIDI in/out subcircuits like on the MB core board going to/from the relevant PIC pins in Plog's thing, and I had some power supply stuff onboard to get my 5volts.

Figures we get some fine soul who's capable of throwing together Windows driver code for a parallel MIDI interface and he goes AWOL on us. ;D  (...joking Plog, take your time and thanks again!)

George

If anyone else here tries one, I'd be interested to hear if it went the same way. 

[stryd_one]

Plog and I were chatting about multi-client support a little while back too, and I've been cooking some things up which I'll mention later.... It's still alive :)

[Jidis]

Stryd,

Try that Plog one if you've got the chips around. I'd really like to see if it does OK, and what limitations it may have for this sort of stuff. I'm definitely planning to get back on it soon, I've just piled up a few too many tasks lately and need to dig my way back to the surface. :-[

I'll likely want to build a bigger one if you guys work one out, but the small one could be pretty convenient if it works. He said it could be stripped down without the status lights and stuff (we usually do without that luxury anyhow), and I'm wondering if it could even be ported down to a smaller chip package or something (maybe built into the sub-25).

Take Care,

George

[buhler]

Oh hey Buhler :)

Yeah, I've had mine a while, but didn't have much luck with it. I mailed Plog a couple weeks ago, but haven't heard anything and didn't want to bug him. From what I can remember of it, I was able to get certain signals coming off of it, but the output wasn't 100% solid, like I'd get pieces of controller messages while outputting notes and stuff, and I could send MIDI clock from it, but not MTC, etc.

I didn't see the input work, but my circuit was a bit of a "mod" and I haven't had the chance to try to strip it down and see if any of the extra stuff was responsible. I also used a 16F819 chip (which Plog said was OK), but it seemed to compile OK with a change or two to some labels or something that were named differently. Main difference with mine was just that I used the two MIDI in/out subcircuits like on the MB core board going to/from the relevant PIC pins in Plog's thing, and I had some power supply stuff onboard to get my 5volts.

Figures we get some fine soul who's capable of throwing together Windows driver code for a parallel MIDI interface and he goes AWOL on us. ;D   (...joking Plog, take your time and thanks again!)

George

If anyone else here tries one, I'd be interested to hear if it went the same way. 

so if i do go ahead with one, i should do it Plog's way?  that's fine with me.  i have a Midi interface that won't run on my Win2000 machine and i like windows better for Mios.  this seemed like a great solution.  when i get the time, i may build one. ;D

[plog]

hi 2 all.

Jidis,  im glad that you finally got the CHIP :)

The main problem why, you can get your MIDI IN to work, i hope, is for F819  features. IT HAS BUILT IN RC OSCILLATOR.

So this chip can work without any external oscillators :)

Make sure, that you selected right mode, it need to be HS OSC2 or something like that, cause as i remember the default is internal_RC.

-

You must have exactly 20.000 Hz frequency.

My midi controller is based on PIC16F819, so here is my configuration line:

__CONFIG  _CP_OFF & _WRT_ENABLE_OFF & _CPD_OFF & _CCP1_RB2 & _DEBUG_OFF & _LVP_OFF & _BODEN_OFF & _MCLR_ON & _WDT_OFF & _PWRTE_ON & _HS_OSC

try to use this. :)

-

But first off all, do you get ON/OFF led near multiplexer when using the device in DAW app. ?

Do you get error led blinking while sending midi events to device and device is ON (mux led = OFF) ?

If so, then you definitely are using INTERNAL RC :) try to change your configuration and try again.

----------------

Next problem, MIDI OUT.

This is known problem :) cause it was made as backward capability =)

And i really do not recommend to use it, because:

1) i'm using KeStallProcessor() API to make 31250 bit rate.

2) i'm rising IRQ level to make sure that no ones interrupts my process (cause i need to send a bits in 32ms intervals, so i cant let CPU to do some operations while timing)

so at one MIDI BYTE, i need to send 10 bits (1 - start bit, 8 - data bits, 1 - stop bit), so it tooks 320ms to send a byte.

in that time, CPU IS FREEZED. so on every byte you lost 320ms of cpu time. the shortest midi event consists of 3 bytes,

so you lost: 960 ms of CPU time on midi event.

Its only theoretical calculations, but it should do sense in real world :-)

-------------

Why dont you get your MIDI OUT perfectly?

Im using 1.6Ghz intel celeron M. and i calibrated that  output loop which sends midi byte over LPT, exactly at 32ms.

( KeStallProcessor(TIME) + time of instructions), TIME - this is a constant, i'll add this variable into Property Sheet, when you could comfigure it as you wish. this value is  0 < TIME <= 32ms. it depends on CPU frequency.

Hope this help, helps you =)

Stryd_one, hi mate. I haven't seen you long time :) How is you doing ?

Do you do some further research on that project? maybe built some prototype -)

sorry that i cant join to it right now. i have a lot of midterm tests and to give an account of study. so i haven't spare time.

I didn't go to lectures so i need to learn the stuff of half-semester at home  ;D

i hope it don't run too long...

cya  8)

[stryd_one]

No sweat ploggy, I have been working on a few things while you were away. Work hard on your exams and good luck!! We'll see you soon :)

[C_04]

Hi

Is this device working? Where i may get schematics and firmware (if necessary).

Cheers

C_04