Stone

When it's done, yeah This is why I don't promise anything...(went back to work and got a new car so I've been hyperbusy)

 

I'll see if I can get back on it soon - ran into a few conceptual problems so I need to get it all straightened out in my head before I go down the wrong path.

 

Stone

The cutouts on the side are not symmetrical

Actually they aren't symmetrical on production carts - that way they can only fit into a cart shell when the board is facing upwards.

 

My actual mistake was that the left-hand cutout isn't just a cutout - the board is wider at the bottom than the top, but my layout assumed constant width. Whoops...

Done a bit more hacking about. This is before the million iterations of 'print 1:1 copy, swear, tweak, print 1:1 copy...' Can you spot the deliberate error?

 

Should really go to bed now ;-)

 

Stone

I'll see what I can manage I had an old EAGLE layout of an EPROM cart I never got around to fabricating which was the source of my cart slot footprint but for some reason it's way out! Lots of tedious counting and measuring to do which is why I've been putting it off...

 

Been quite distracted recently with other stuff - but on the bright side I now have a working Time Crisis in my living room I'll have to try and get back into it soon.

 

Stone

Just say that in case of you used input in the same time.

That's what magic numbers are for, right?

 

Stone

Tell me you're not building a flash cart

I'm not building a flash cart.

 

Actually what I'd really like is a USB BJL cable - wouldn't be a hard project but I can't really be arsed

 

Stone

Aww, you guys Another of the pieces fell into place earlier but again I can't tell you what it was without giving the game away! Hurrah for people who keep stockpiles of everything just in case. Also acquired a laser printer off Freecycle so I might experiment with toner transfer PCBs for quick prototyping. It's already been invaluable in printing out 1:1 PCB footprints so I can line parts up on them and check the spacing. My cart edge connector was seriously wonky!

 

After SCPCD's post above I've realised I've screwed up a big chunk of the bus translation logic (and it will get much worse if I allow the Jag to write into the cart!) so I'll have to redo a big chunk of it, which is very irritating. Better now than after the first PCB is made, I guess - I'll have to stop designing stuff so early in the morning. Probably about half of it so far was done between 10pm and 4am

 

If you use UART, make sure that there is no JagLink connected to the Jaguar.

Why? Obviously all the data sent from Jag to cart will go out externally too, but why should I care? Does adding a JagLink change something in the hardware side?

 

You need the ROM1 because the bus is shared with the boot rom and also by the JagCD boot rom.

On the JagCD, there is a bit in a register to switch between the internal ROM or the external cartridge that ROM1 will control.

That makes perfect sense, thank you for reminding me.

 

If the memory controler is set to 32-bit mode, a move.w will change the state to only one, not both.

PS :

- the 68k can not make 32-bit access : a move.l is 2x16-bit access

- the blitter can made 16-bit access : depends of the configuration. (pixel mode, etc...)

Again I'd forgotten these things I'll make sure I attach all the relevant pins then, when I've used EPROMs in the past I've just tied BHE and BLE pins active. In this case (16 bit memory ICs) I'll tie BHE and BLE to /EOE1 on one chip and /EOE0 on the other.

 

Stone

What are you up to ?

Patience! I promise it will all make sense in the end...

 

TXD and RXD are the I²S data pins for audio, and are directly connected to the same pins on the DSP port [...] Those signals are not related to the UART used for networking.

OK, that makes sense. I never really looked into how the JagCD hardware worked in detail, I was always happiest at $4000

 

UARTO is the output (TXD) of the UART, and UARTI is the input (RXD). They're the same signals than those on the DSP port, which are used by the JagLink, etc.

Yep, got it now. I hadn't realised they were pinned out to the cart port, it makes it a lot easier to talk to custom hardware than by reading and writing magic addresses in cartspace! (also much easier to debug when you do the Jag software - just use an Alpine and listen to the serial port for your commands/data)

 

Yes, this is the chip select for the cartridge space ; you can't get rid of it, sorry !

I was thinking of the different EPROM access methods - many datasheets include one where the chip remains selected (/CE low) at all times and you control reads and writes just by using /OE and /WE. I have scrounged some more level translation pins together now (had to add another small bus tristate for pins going into the Jag - E2DATA, /RESETI, UARTI etc) as I had almost filled up my 74LVC16T245s and couldn't spare eight bits to swap the direction around. The PCB layout is going to be a nightmare, I'm trying to think ahead at the schematic stage but it's not always obvious what will make things hard later...

 

/EOE1 (pin B22) is active for read accesses to bits 31..16, /EOE0 (pin B23) is active for read accesses to bits 15..0.

OK, yeah, so for 32-bit accesses they'll both be enabled at once. There seems to be a lot of flexibility in the memory controller for different cart designs - was the 1MB cart they did for Cybermorph a 16-bit-only one with one maskrom?

 

/EWE0 is low during write accesses to bits 7..0, so it should be connected to /WE if you've got RAM or Flash memory on your cart, etc. /EWE2 is the same thing for bits 23..16.

ERW indicates whether the current bus cycle is a read or a write, but I don't remember the polarity. Ask SCPCD

Do you mean /EWE0 for bits 15..0 and /EWE2 for 32..16? Or can you only write in small widths? Very strange

 

Pressing * and # together doesn't do anything particular on the hardware side ; the game has to detect and handle in software.

/RESET is active only on power up (it's longer than a few milliseconds, but I don't remember how much ; that's another thing for SCPCD to answer), when the cart asserts /RESETI, or when you press the reset button if you've added one

Yeah, adding a button isn't hard, that seems the easiest way.

 

Sorry to be so cryptic, it will be worth it in the end though!

 

Stone

Finally had a bit of time to do some schematic work on this, I've been really busy! I have a few more stupid questions if you don't mind…

 

1) Are TxD on B49 and RxD on B50 just attached directly to the same pins as on the external network port, and can you talk to them using normal Jag networking code? Do you need to use SCK/WS with it or are they unrelated? Also, what are UARTO and UARTI for?

 

2) Am a bit unclear on ROM1 (pin A20) - is this /CS for the cart memory ICs? Can I just leave it tied low on the cart and unconnected on the cart port or is it actually used? (am running out of level translator pins )

 

3) Likewise /EOE1 (pin B22) and /EOE0 (pin B23) - Matthias has B23 as OE for the high word and B22 as OE for the low word, is this correct or is it backwards? I assume they always change state together in 32-bit accesses anyway so I may be able to get away with just one…once you've told the memory controller to run in 32-bit mode are all bus accesses always 32bit from then on even if you use mv.w?

 

4) A0 and A1 are always low for 32-bit accesses, correct? (so I only need A2 - A23 hooked up to the memory - A2 on cart port to A0 on my memory IC)

 

5) How do you use /EWE0, /EWE2 and ERW?

 

6) /RESETI is for when the cart wants to reset the Jag, but how does /RESET work? Is it just active for a few ms on powerup or does it fire under software reset (*+#) also?

 

Just checking!

 

I'm making EAGLE libraries of all the parts as I go along so if anybody would like a copy once they're finalised and checked then do get in touch and I'll share.

 

Thanks in advance!

 

Stone

Yes, but when a cartridge is inserted into the JagCD, it starts even if there is a CD in the drive. So there's no way of running the dumping program from the CD, unless you have the BJL ROM installed.

 

Or maybe you know a way to start from the CD even when there's a cartridge in the JagCD slot, in which case I'd be very interested to know how !

Both, actually! I used to use a BJL-equipped Jag to dump carts with and uploaded the program to RAM manually. However I believe the developer JagCD BIOS allows you to hold buttons on boot to specify whether to prioritise cart or CD - speculation only, but otherwise I can't see how their 'jukebox' program (let you run a CD program which wrote cart ROMs to an attached Alpine) would work. If not, once the Alpine has a cart image in it you can't run the CD jukebox program again! I can't for the life of me remember why I put the cart transfer program on a CD, there must have been a reason...

 

With an Alpine you can work around it by loading the CD BIOS into RAM directly and jumping into it, but it's a bit of a pain. This is how I use my prototype JagCDs as they have no BIOS installed!

 

Stone

Requirements :

- a way to upload a Jaguar program with a game cartridge inserted (currently, the only option is a BJL-modded Jaguar)

The dumping tool I used waay back was a BJL program that spat data out of a Jaglink, through a RJ11->serial cable and was collected as an xmodem transfer by a PC running Hyperterminal - I think it was written by Glenn Bruner. We used to run it from a CD. I was reminded of its existance when I found a CD of it the other day along with my dumping cable

 

Stone

Many thanks for that. It looks kinda like Matthias traced a 4-chip cart without knowing which ROM was which! Also thanks for the edge tip, I'll bear that in mind. This is all very useful, you've saved me two board revs already

 

Stone

Oh, and are there any more errors in the schematic I should be aware of, other than both joypad ports being for Controller 0?

It turns out the answer was yes...

 

The cart port in the schematic has D0 as A23 and D16 as A40, whereas Matthias's website has D0 as A40 and D16 as A23. The rest of the data lines seem scrambled about also. Could someone confirm if Matthias's diagram is correct?

 

(if so why would they use D16 for data into the E2PROM? D0 makes more sense, kinda )

 

Stone

I still remember enough French from school to get by

Yeah, whoops, it was past my bedtime

 

I'd forgotten about the diodes, I was thinking of latch-up. Thanks. Looks like the easiest way is to buffer everything through a simple PLD, then as an added bonus you can rearrange the pinout to make it more convenient! I think you can get ones with multiple VCCio domains so it can become true 5V signalling as it leaves the cart.

 

Cheers chaps, it's very refreshing to have people on a Jag forum be both well-informed and friendly!

 

Stone

Oh, and are there any more errors in the schematic I should be aware of, other than both joypad ports being for Controller 0?

The cartridge's data bus is internally buffered by 74ACT245s in the Jaguar. Since they're designed to be compatible with TTL levels, 3.3 V CMOS signaling should work fine. Beware that the bus is pulled-up to +5V with resistors, though, so both the inputs and the outputs of your 3.3 V devices must be 5 V-tolerant. (74LVCxxx chips are fine for this).

I might have to read the schematic to get this straight in my mind. Are you saying if you drive the bus low the IC sinks (5V*pullup resistance) internally, and if you drive it to 3.3V you have the pullups trying to pour (1.2V*resistance) into the output driver? How does this affect your Flash chips etc, or do you just buffer all the outputs? This is exactly the kind of pitfall I was hoping to be warned about so thanks! I don't mind making mistakes as long as they can be fixed in software...

 

I don't believe you :-D

Suit yourself

 

The RESETIL (on B33) signal is directly connected to the reset logic of the jaguar.

An assert on this signal will reset all the jag (the RESETL on B18 will be asserted to) and logically, the cartridge data line will be tristated.

Perfect, thanks. I haven't had a good look inside a Jag for ages but all the ones I have here are rare stub ones! If I can't find a retail in my parents' house this weekend I might have to buy one

 

Stone

Hi all,

 

Share your wisdom! 3 questions for now: (more as they arise)

 

1) What happens to the cart bus when a cartridge asserts nRESET? I know it causes a 68k NMI but does the memory controller see it also? Does the bus freeze in its last state, get tristated, neither? Can you hold the line low forever to keep it reset forever?

 

2) I know some of you use 3.3V devices on your custom carts (Zerosquare) - does the Jag accept 3.3V signalling or do you translate it? Obviously no problem to do either (or combine it in a bus tristate IC) but no point doing it if you don't need to bother.

 

3) Does anyone have the section of the developer's manual (cartridge and expansion port) that's missing from Starcat's copy?

 

Thanks in advance, and no, there's nothing to see here

 

Stone

Hello all, and may I include in my first post here an apology for upsetting Tursi on AA Not my intention.

 

Most of you have 'met' me before. When I was first scene-active in 2001 or so I was still at school. Now I have an electronics degree, a gf of 5+ years, a house and a job I still have a soft spot for the Jag even after all this time, and I seem still to retain chunks of the dev manual no matter how hard I try so it looks like you're stuck with me

 

I've mainly joined here as it seems to be an oasis of technical detail (with a hardware slant too, yay!) and I'm considering a couple of projects along the lines of what I know best. I don't like releasing details of what I'm thinking until I'm in a position to deliver but you'll probably find me asking cryptic questions from time to time and then lurking some more...

 

So, hi to those who know me, hello to those who don't and yah boo sucks to the dicks who have to spoil it for everyone

 

Stone