Getting the genesis online

[Archer]

I already talked about my project in my first topic. I am going to connect an ENC28J60 ethernet module to the controller/EXP port of the megadrive. I plan to use this thread as a log for the project. Thanks to devster's serial bootloader, i can finaly start development without swapping the SD from my everdrive for every change in the code.

I started last night and continued until around 03:00 in the morning, but i got some first results. I connected some LED's to the port and when i saw them blink i knew the project has started

UPDATE: 25-01-2011:
I just had a great idea, I think it would be awesome to create something like SEGA Channel that uses a site or PC in your network to download mini-games into RAM and VRAM. Another use can be uploading graphics to VRAM from the PC, and see how the real hardware displays it on TV. Even move sprites and backgrounds around the screen. Would really help development and understanding of the VDP. Or try a sound sample with the actual sound hardware. I don't know if this might be possible, since sample data goes into RAM.

For streaming i think the connection is too slow and CPU intensive, but access to the VDP must be possible

[madcrow]

Very cool. BTW, I noticed that you're attaching the Ethernet thing through the controller port. Do you think that maybe that could be developed into a multiplayer system?

[Anonymouse]

Wow this is awesome. I have recently been thinking about such a development, though I personally do not have the skills to do so. I was thinking it would have been more possible through adding a usb port to an everdrive device which connected to a pc/laptop and accessed the internet from there. Obviously you have more knowledge on the matter. Im very very interested in seeing how this develops.

[Archer]

@madcrow: I think multiplayer is possible, but you will have to write the game around the driver and network stack.

@Anonymouse: I have used this Ethernet module before so it was a logical choice for me, because i know how it works. and it only needs about 6-7 wires for the interface. Using the USB + PC option would create a lot of extra complexity, and would not be standalone.

I still have a lot too learn about m68k assembly and genesis programming. I only got the console for about a month, but i think i got quite far already.

[villahed94]

Archer, you can use also the new development forum, it´s called "Blast Processing" in this same site

[Archer]

Archer, you can use also the new development forum, it´s called "Blast Processing" in this same site

Thanks for pointing out the new forum. I just read the thread about it last night. That was after i started this one.

I want to ask an Administrator if this thread can be moved to Blast processing Please?

[Archer]

UPDATE: I did some test's and i think the best possible speed i can get is about 10Kbps. This is still much faster than the RS232 serial option of the controller port which can do max 0,47kbps.

But this would mean the CPU is doing nothing else than sending out bytes, so actual speed will be lower. it might be possible to get more speed by using a microcontroller between the controller port and the ethernet module. But for now i will use the slow method, just to see how far i can get.

I think i spoke too soon about multiplayer being possible

[Archer]

I just thought about the sega channel. Maybe this can be used to recreate that experience. not that i ever used it, but saw some video's on youtube.

You just need an interface on the mega drive and a website with special games designed for this system that load into RAM and VRAM. In combination with an everdrive games could be written to SD card.

This would give homebrew a way to reach other players that can find the games and play it on real hardware.

i know this might not happen soon, but this is definitely one of the possible uses of an ethernet connection.

[villahed94]

Archer, you are very clever, revive sega channel, and why not? revive the actual carts too.

[NeoVamp]

I just thought about the sega channel. Maybe this can be used to recreate that experience. not that i ever used it, but saw some video's on youtube.

You just need an interface on the mega drive and a website with special games designed for this system that load into RAM and VRAM. In combination with an everdrive games could be written to SD card.

You might wanna search this forum for XBAND, lotsa talk has been going on about that.
apparently some people managed to get the Xband source from the original devs.

[Archer]

You might wanna search this forum for XBAND, lotsa talk has been going on about that.
apparently some people managed to get the Xband source from the original devs.

I have done some reading on XBAND and it looks very intresting. Unfortunatly you need special hardware that's between the game and console to sync the games. My guess is the XBAND applies a patch to the game ROM just like the game genie, of course it's more advanced and more complicated. The cool thing about XBAND is that it allows you too play original two player games online.

My project is a bit different. Games would have to be modified or designed for the hardware. It would be more targeted at homebrew and easy development. It does give some great ideas about what would be possible.

I think speed is the biggest problem. The ENC28J60 can do 10Mbit but my interface can not go that fast. I did some rough early speed calculations and think the beste speed i can get is 10kbps. That's the speed of software controlled SPI though the controller port. I plan to switch to an interface controller that goes between the controller port and ethernet module.


I had never heard about XBAND before. Thanks for the info.

[Archer]

I have made some progress. The SPI_Transfer loop is working, although it's not sending anything useful yet. I included a screenshot in the attachment. The cycle for one byte takes about 75us. I again calulated this to give raw speed of 11,72kbps.

[TmEE]

SPI will be painfully slow... unless you have a chip that does SPI management on the MD side...

I personally would go for a controller port to PC LPT/USB cable and have PC act as the NIC. That way you can achieve speeds around half a Mbit. If you connect some old ISA NIC to the MCD connector or cart you will get several MBit speeds :3

[Archer]

SPI will be painfully slow... unless you have a chip that does SPI management on the MD side...

I personally would go for a controller port to PC LPT/USB cable and have PC act as the NIC. That way you can achieve speeds around half a Mbit. If you connect some old ISA NIC to the MCD connector or cart you will get several MBit speeds :3

The module i want to use is based on SPI, and i have successfully used it before with a 16F72 PIC micro controller. I have already been thinking about a PIC to translate SPI <-> CONTROLLER_PORT 4bits at a time. This is the first programming i do for the motorola 68k. Right now speed is not important for me, i will just keep in mind that i am replacing the SPI routines later.

Using a PC to do the hard work takes the fun out of it for me. And would require a PC/Laptop near every console to go online.

[Archer]

UPDATE:
SPI is almost done, got it sending out bytes now I am going to connect a MCP23S16 SPI I/O expander to test the receiving part. I made a small circuit a while back with this chip to connect a 2x16 LCD to SPI.