Alan numitron clock
SNES Pi Webserver
USB Volume/USB toys
SNES Arcade cabinet
Game boy projects
Home Presence Detector
Rand Nerd Tut
Carnet du maker (fr)
ATmel blog (defunct)
Around a SNES
ardPowerSwitch project and case the SNES (if working) in something else !
2012-04-11 : auction on Yahoo, got a junk SNES with 2 pads and cable for about 2000 JPY (around 20 euro). A bit expensive but if I can make it revive I can sell back one of the two on internet... I can start thinking of the arcade pad... expecially since I found a small flat portable TV/DVD player in the garbage (it's working of course, I love Japan).
2012-04-27 : bought an extra video cable for 2.5 USD on ebay working fine. Bought the arcade style buttons and joystick, tested the connection to the TV (works ok)... now just have to make an arcade controller as proof of concept and we'll think of the arcade design.
2012-07-31 : well ... I left it on the side but it's not working much for now. My problem is to answer in a timely fashion to the SNES it think.
2012-08-01 : key is 1) 2 signal so use 2 interrupts pins and 2) for reading the button input status it's PINB not PORTB (used for writing status) ... (sigh) Things should move much faster now.
2012-08-02 : yeah indeed, now it's working just fine. One thing to know, doing bit masks with 16bits value can confuse the compiler. Force it to work 16bits in that case with an explicit cast. my16bit ^= (uint16_t)(1 << 7); Now I can send nicely start and right, I'll start building the housing cabinet and we're just a few solder away of the result!
2012-10-10 : finally it's working. Main issue was timing so I rewrote everything in ASM. However I had still a few issues fixed with the logic analyzer bought this week (couldn't have without it). Final error was the attiny2313 that was finally dead and did weird things all the time. Replaced with another one, it's working nicely now (^^)
Attiny2313, internal oscillator 8MHz, code in assembler.
It took lots of trial and errors : with the right method took only a couple hours, but it took me months on and off to figure it out : use interrupts ! I won't detail SNES controller protocol here, check the links for that but let's settle this once and for all : the SNES reads on RISING hedge of CLOCK. My controller uses 2 interrupts plugged on LATCH (INT1 - PD3) and CLOCK (INT0 - PD2) pins, matching the following chronogram :
Why not just redo and copy summary another guy's job ? It wouldn't have bothered me to do so if I could have said I understood what the other guy did (used chip internal USI, smart move). But honnestly that was not some job I could have redone myself, so I took the pretext to work on asm and interrupts and build up my own competence one step at a time. Now you have another way to do it, less elegant but not ugly, and working nicely.
The code is in summary reading the button status and storing the result in a word (16 bits). At the start of the sending session, use a cursor from 0 to 15, create a bit mask (1 << n) and send the status. Agreed, a few weeks after, it all seem to me a non optimized way of doing the job (not wrong, yet not appropriate with my time constraint). That's how I wrote it in C and I tried to translate it to asm... which I did, but painfully.
Just to point it out, the main challenge here was the timing. Running at about 8MHz you have 8 cycle every 1us, and between each front of the clock 6 uS (double if you cheat like I did), so it gives you at maximum 48 cycles, minus the interruption, jump, ... you better think ahead your data structure to make things fast. I learnt a lot of with that relatively simple exercise and there is still a lot to learn to make it super optimized (there's plenty of room for improvement in my code). Maybe if I make another SNES cabinet...
➮ About the timing issue, to gain a few cycle an alternative was to precalculate some data, store in SRAM, load it from SRAM. Mainly for the shifting of bit mask, since you can shift only one rank at a time (and it eats your precisous cycles). Even better, the whole status of the buttons could have been stored in a byte array in memory and read one by one too (super fast I think). But you only have those ideas once you have banged your head for weeks on the wall and finaly got it work the way you imagined at first (sigh). Next time I write such a controller, I'll use this solution (way better).
Sample chronogram : A0 is the value pin (top brown), A1 is clock (2nd from top red), A6 is latch (bottom pink)
How I wired it, so feel free to do it your way. In blue the buttons, in red the SNES connections, the figures on the sides are in which order the data must be sent (start at 0)
(deprecated - the C version that has wrong timing http://code.google.com/p/alanarduinotools/source/browse/#svn%2Ftrunk%2FAttiny2313%2FAttinySNESPad)
Use a ＮＪＭ２０７３Ｄ double amplifier .
Sound diagram - the wiring of just one channel is drawn, it's same for both.
The cabinet details and building photos are at Around a SNES - cabinet photoroman.
7 pieces of 45x45x0.5 cm of plywood (contreplaque in French), 3 pieces of 3x2.5x200 cm of cleat (tasseau in French), some putty (mastic), sand paper, jigsaw, hammer, sweat, imagination and a few spare hours.
I fixed my alim adding 2 serial diodes, now I'v 10.5 v input and the console is working just fine (never put that faulty game again inside).
Oh and it's getting quite hot ! The radiator is a must.
a big radiator on it and still it's barely touchable after 5 minutes. According reading on the net it must go up to maybe 50-60 C (after that you can't touch/stay touching).... I think I will add a few holes for air to go through the case.
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