Options to MIDI Sync the NES? (Page 1 of 4)

Famislayer plus FamiiDI

Has been explored, and would probably work, I know I'm interested.

Hi Yogi!

Yep I've reached a similar conclusion after Mrwinner provided some links. I think FamiSync + PowerPak + FamiDI would work well! I wonder if I can sort of combine efforts and use 1 Arduino for both ArduinoBoy and the pulse output to the NES. It's too soon to say though. I use a stage-hardened custom ArduinoBoy with a noise rejection circuit for the GB called StageBoy and being able to add in NES support in a revision 2 would be awesome, and also keep things less cluttered on stage.

Anyways don't want to get off-topic - this solution sounds like it is exactly what I'm looking for! I still need to read through all the information but yeah it looks like a workable solution exists. That makes me stoked! I love the GB and LSDJ but I've been missing that NES sound for our live shows and have been really wanting it back.

I'm not entirely sure what that thing actually does Is it listening to audio and then matching BPM to a sync out?

Our setup is kinda complex - we use a GameBoy (LSDJ) with a MidiBox SID and MidiBox FM and then also do live playing of (usually acoustic) instruments on top. As a result, I need some level of MIDI sync, which is usually handled right now via Reaper. I'd like to switch to using a hardware playback device, like a MidiBox MIDIO128 but I haven't made too much headway on that yet.

Adding in the NES to the MIDI chain won't be really a big deal. As it's just clock sync I'll probably mod my current StageBoy to see if I can use MIDI Thru and then hook up whatever interface I end up with on the NES to that. The primary blocker was an NSF player that could respond to a clock, preferably with some transport controls (so it starts playing when it sees the first clock pulse).

Yeah I'm trying to compile all this somewhat disparate data together. It looks like most solutions are just sending pulses? So all I would need is to add in the NES output section to the routine that handles LSDJ slave output to the GameBoy, maybe plus start/stop - I think

While I've made some updates to the ArduinoBoy code to better fit my needs for my custom one, I haven't dug super deep. But it looks like there is room to spare as far as code size and processing power to add in the NES functions.

Last edited by m00dawg (Jun 27, 2014 4:44 pm)

Well I was thinking that by watching the bytes sent out (if midi Thru is part of Arduinoboy code) a sync function would work with both the Arduinoboy in Master or Slave mode. Otherwise you will only output sync when the GB is slave, which may be fine also (?).

The basics of the timing:
Most NSFs are played within the NMI at a refresh of 60Hz. which works out to 3600 calls to the play frame address per Min.
This is the same as a Midi clock running at 150 BPM. The midi Clock messages occur at 24 ppqn, so at 150 BPM: 150 x 24 (ppqn) = 3600 tick bytes per Min. What I'm driving at is with a Clock running at 150 BPM your NSF should sound 'normal'. So there is no heavy math in the firmware, just detect the Midi Tick byte and pulse the trigger button.

The other issue is the connection to the CD4021 in the GamePad. The Buttons are active low logic; I.E. when 'Open' a 10K R pulls the pin high, Closed to GND. So to drive the 4021 pin we need to setup our uC for Open Drain: a 1 = Pin as Input, 0 = active GND. To press a button we Output a 0 and to release, idle the Pin as a Input (neither sourcing or sinking);
1. During Init, set output Pin latch data to 0 for each GamePad button we want.
2. Then switch Pin between Input and Output for triggering a button (output to trigger, input for release). Beware: with the PIC, there are issues with the Read-Modify-Write structure of the ports, but I don't think the AVRs suffer from this.

For Start/Continue/Stop just need to switch the 2nd Pin direction according to the received message; Start/Continue = button pressed, Stop = Button released. FamiSync handles this manually but its a easy change.

The Tick pulse width is still up in the air, but I am starting with 2-3mS. It really depends on the NES code; how responsive the code is reading the controller. Once I get all the hardware running together I'll have a better idea.

The ASM  for my 'F628 is like 400 words and uses about 5 ram bytes ATM. So I would guess the Arduino code would be similar.
Yogi

Wow thanks so much for all that awesome info, yogi!

Hmm so timing wise, if I'm at a BPM other than 150, I should generally be ok although going above 150 I might have issues? I actually don't know how much of the timing has been looked at in FamiSlayer or how much that would be an issue.

I'm also a bit confused on having to set the pin to INPUT or OUTPUT mode - is this is due to the CD4021? Bypassing it won't necessarily fix the issue directly will it and just hitting the serial interface directly?

Good call on Midi Thru. I new it was a simple mod, though I've never actually had to do it yet

+1 to everything yogi said, just have one comment to make...

The 'resistors' (actually just lumps of 'resistive material') in a NES GamePad are actually 38K, not 10K. Here's an old Ben Heck article with some more detail:

http://www.extremetech.com/extreme/7468 … ent-system

and here's an example of 10K resistors not working in a project:

http://forums.modretro.com/viewtopic.ph … mp;t=10742