nesdev.org

I'd be interested to see if it would be possible to use the 2A03's DMA to move packets in and out of the Wiznet chip...that would be really cool. Not possible. The DMA on the NES is for updating the PPU sprite ram quickly during the vblank. It is hard wired to write to $2004. It's not targetable.

Oh and the speed of using the Wiznet chip, even in indirect addressing mode would be much faster than the SPI Microchip part. The way the indirect addressing works is that there are four registers at the base of the MM I/O space in the Wiznet chip (thus only needed two address lines from the cart po...

But I would almost recommend using the cartridge slot instead of expansion port for all of this. Sure it's a semi-custom mapper, just modify an existing mapper to give you some space for Ethernet I/O. But it's not like the firmware to use the Ethernet isn't going to be custom anyways. Being able to...

Alright, I just had time to desolder the expansion port connector from my spare NES and I'll be FedEx'ing it to the Sullins' engineering department to get a quote for custom connectors that mate with it. Cross your fingers that the quote will be reasonable. I just emailed Sullins to get an address t...

I have a plane trip tomorrow and then again on Friday. I'll take along data sheet print outs and see if I can bang out an initial schematic for the EtherNES. Even if the connector takes more time and effort, I'll be able to at least build an initial batch of 4 EtherNES peripherals out of the parts I...

I was reading through the wiznet data sheet and the interrupt thing won't be a problem unless it listening on an open port that is being flooded with connection requests, but that is a problem on regular PC's too. The wiznet part only yanks on the interrupt pin when a packet is received on an alread...

So I guess, the easiest way would be to make D3 or D4 just return a well know bit sequence over and over again. We could hook it up so that subsequent reads to D3 always return 11110000 or something. The code could read from the register a bunch of times and if it gets 11110000 on D3 for each set of...

Whoa, I just realized that there may be an even easier solution for the EtherNES than the PIC. Check this chip out: http://www.wiznet.co.kr/en/pro02.php?&page=1&num=25 The Wiznet 5100 has it's own internal TCP/IP stack, 16 kb of transmit memory, and integrated ethernet MAC/PHY. The best part...

Regarding the keyboard, I'm thinking it would probably be cheaper and easier just to use a PIC 16F84 to power a PS/2 keyboard dongle. The PIC would interface with the PS/2 keyboard and then send the scan codes when the 2A03 clocks in the button states. Since there are 8 buttons, that would mean that...

Here are some extra credit points: 1. Figure out a good source for an 8x8 matrix keyboard. 2. Figure out if it is possible for us to hook up some 8-bit latches to the keyboard and then what it will take to hook it to the second controller port so that when the 2A03 reads the status of the controller...

I just realized that yanking on the 2A03's /IRQ line won't be enough to signal that the PIC has data to read. We'll also have to assert one or more of the controller pins in the expansion bus. If I'm reading the docs right, controller input signals an interrupt in the 2A03 as well. If it does, then ...

Looking at this book: http://books.google.com/books?id=CB9GaAU1dwsC&pg=PR23&lpg=PR23&dq=Microchip+PIC+parallel+slave+port+interfacing&source=bl&ots=Hfe6x_ruch&sig=k9OfP1ieu54iPCVqnM28x4TOsBk&hl=en&ei=tF_4SY3mBJTOtAOVj8ThDg&sa=X&oi=book_result&ct=result&...

Alright, technical detail #1: the parallel slave port (PSP). I'm trying to figure out two things: 1. Can we interface the 5V 2A03 logic directly to the PIC? The data sheet says yes. The PIC is 6V tolerant on all I/O pins in digital mode, so we should be able to go from 5V to 3.3V. The logic threshol...

Thanks, but I think I have a dead NES around here somewhere. I'll go check and let you know.

Super-Hamster is right about the PowerPak pins. I plan on developing my EtherNES compatible game using a PowerPak Lite that I plan on modifying to route the right signals to the expansion port. I haven't looked at the PowerPak Lite schematic in any detail at the moment. I propose that we choose pins...