Thanks for the input. But I don't agree with your assessment. The cartridge needs a full set of standard connectors and this can be only achieved with the adapter board. The board is designed so that it can be plugged either to the top of the cartridge or connected to the cartridge with a standard IDE cable. The IDE cable allows more flexibility and safety when using a lot of wires.
You can still solder the music keyboard connector onto the cartridge board and use the audio socket for output. Then the only thing missing would be the MIDI, but you can still install the 4x2 pin connector and build the adapter using the female DIN5 plugs. Taking into account how many people are using MIDI these days we consider missing MIDI outputs an inconvenience rather than a problem.
But I still find the adapter board very ugly. It's an extra object on the table to mess up and mess up.
I still consider SD Snatcher's idea of using 3.5mm TRS for MIDI outputs a great idea, since the use of the 3.5mm TRS to DIN adapter cable is already considered a standard. Only two simple cables with a TRS 3.5mm pin and the DIN on the other end were dispensing with the complicated and annoying handle of flat cable of 40 tracks.
In addition this reduces the cost, not requiring two boards.
In SFG module the MIDI IN uses galvanic isolation, the design and the way DIN5s are connected to the ground and to the YM2148 chip has to be taken into account. Our engineer blasted the first expansion board draft where the DIN5s were not connected the same way as on Yamaha's original schematics. On the picture in my previous post the DIN5 connections are as close to the original design as possible. I doubt you can achieve this using the TRS connectors.
We will release the sources for the boards and then anyone can do whatever modifications he needs.
Thanks for all your hard work Alexey and bear service crew! I'm really excited to see the SFG become available to more people! I'm a big fan of the YM2151. Hope someone will produce a few batches of these soon!
Later. We are doing the cartridge based on the original SFG schematics from Yamaha. The only difference is that all the logic (except the chip for 4MHz generator) and YM2148 chips are emulated by Altera. And the amplifier was "borrowed" from the Carnivore2 cartridge to save space. All the rest is the same.
So if I read correctly, the "base" cartridge is a fully functional ym2151 cartridge with headphone out, and optionally you can use the adapter for midi/kb connection. So I don't really see a problem with the extra expansion board. If you are gonna use those ports you will add some extra cable anyway.
Maybe those who think it will be messy, can reduce the "mess" by using a round cable. I dont know how many connections the cable needs, I count 24, is that correct? maybe a db25 connector + cable? http://www.gearnuts.com/store/detail/GoldDB25-5
With ultra-rigid specifications Gold-plated DB25 connectors for only $154.95, the cable will
emphasizes the lovely sight between both boards.
Keep on the good work, Alexey and RBSC!
So if I read correctly, the "base" cartridge is a fully functional ym2151 cartridge with headphone out, and optionally you can use the adapter for midi/kb connection. So I don't really see a problem with the extra expansion board. If you are gonna use those ports you will add some extra cable anyway.
Yes, the base cartridge is a fully functional SFG module with the selection between 01 and 05 versions of BIOS and line out output via the 3.5mm socket. If you plan to use only the music keyboard with the module, you can solder the 20 pin right angle connector on the base board (with pins facing upwards). If you plan to use RCA output and MIDI together with the music keyboard, you will need the expansion board with its full size connectors.
We have finished prototyping and the first batch will be ordered next week if the boards pass the design review.
