Some time ago I started a small project to connect opl2/3lpt to Atari ST/f030. From pcb it looks like it started it last year .
In general I've rewired pins a little and created two test boards (with and without diodes (one version for easier debugging of Centronics/Printer port), second one for standard user). I'm not electronics expert, so sorry if anyone sees something very offensive. This is the very first PCB in my life, so probably isn't the best in the world. I've tried my best to not kill both opl3lpt and Atari (values of resistors are from ceiling on schema, so see photos for actual value, I use one type).
Wiring looks like this:
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OPLxLPT CENTRONICS F030 ST 1: A0 -> /Strobe CTRL-0 1 /STROBE 1 /STROBE 2: D0 <-> Data0 2 /DATA0 2 /DATA0 3: D1 <-> Data1 3 /DATA1 3 /DATA1 4: D2 <-> Data2 4 /DATA2 4 /DATA2 5: D3 <-> Data3 5 /DATA3 5 /DATA3 6: D4 <-> Data4 6 /DATA4 6 /DATA4 7: D5 <-> Data5 7 /DATA5 7 /DATA5 8: D6 <-> Data6 8 /DATA6 8 /DATA6 9: D7 <-> Data7 9 /DATA7 9 /DATA7 14: /RD -> /Linefeed CTRL-1 +5V +5V 16: /WR -> Init CTRL-2 11 /BUSY 11 /BUSY 17: A1 -> /Select CTRL-3 17 GND (OPL3LPT only)
Real thing like this (it's not final, because I will make it more condensed and nicer to connect):
I've got an issue with dev adapter and diodes. OPL3LPT is powered up from usb adapter and I stole 5v from pin 1 of usb port and wired it via resistor to pin 14 on OPLxLPT side, so it is in high state all the time (connected via resistor just to be safe).
When usb power is connected on opl3lpt side:
With connected D1 diode it light s up and is bright, but all other diodes don't light up at all.
With removed D1 diode. All diodes begun to turn on/off according to signal from lpt port(as expected), but are very dimmed (like current was really low and blue diodes, which are more power hungry don't lit at all - my test program which turns on/off data lines lits every diode beside blue ones).
With usb power is disconnected on opl3lpt side:
Everything works as expected, but d1 isn't lit, because it isn't powered up from pin 14. Diodes are bright.
Here is without usb power (state on f030 boot, /strobe and /busy set to high):
Here is with usb power (state on f030 boot, /strobe and /busy set to high):
So, I've got several questions here.
1) Anyone more electrically competent could tell me what I'm doing wrong here and how to fix those issues with dimmed leds?
2) Data lines / signals are not suitable for powering diodes (bare wires), how I could protect them (psg and computer) better when attaching diodes? I imagine resistors aren't good enough.
3) There is no possibility to switch opl3lpt to read state right now, there is not enough signals on Atari side. Maybe anyone has suggestions how to overcome this? But it isn't very relevant, just nice thing to have.
Only f030 can enable opl3 features, because Select In line can be set to low/high. On ST there is no possibility to enable opl3 features right now.
Any suggestions welcome, still working on test programs/drivers for it. Unfortunately I haven't managed to produce any sound with it yet, so it's still work in progress (I've adapted sample tune replay by Daniel Illgen targeted for cartridge port, but still it isn't working as expected with this adapter, probably bad timings and/or still something hardware related I'm not sure).
Here are some better pics of adapters and opl3lpt with mods I mentioned above: