As I have told several times in this forum, I'm trying to make my own SNES boards for developing purposes. I recently sent to production a lot of 10 boards and I managed to load my own code on the EPROMs in them.
But now I have soldered a PIC12F629 to those boards and the games run perfectly on my Super Famicom (as they did before adding it using an adaptor) but they don't in any of my 5 SNES PAL decks. Sometimes the game freezes randomly, sometimes it restarts, some others I lose any video output from the console desk. And those freezes occur when I've been playing 10 minuts, 50 minuts or a few seconds.
Since it sounded strange to me that the game runs fine on a Super Famicom, I recalled that Super Famicom has DC power inpunt, whereas PAL SNES has AC power input. I thought then that original boards have one capacitor around each chip on the board and then concluded that some AC power input noise was affecting +5V on my boards and made some data corrupt. This AC power noise was not present on Super Famicom and that was the reason the boards worked there. I used 10nF capacitors but... does anybody know which capacity have the ones found in the original boards? Do you think this decoupling capacitors are really necessary?
The fact is that those freezes have disappeared with the 10nF capacitors but the problem has been partially fixed: now sometimes the SNES reset itself again and I lose video output from the console, so I guess CIC's reset is being triggered, and that can only mean that SuperCIC is not giving the proper bit sequence and SNES lock CIC is resetting the CPU. However, this DOESN'T EVER happen on a Super Famicom, only in PAL SNES. What could be happening?
Maybe some noise coupled again on the PIC? Has anybody got some schematics with the proper PIC connection to the cartridge board?
Thanks!
But now I have soldered a PIC12F629 to those boards and the games run perfectly on my Super Famicom (as they did before adding it using an adaptor) but they don't in any of my 5 SNES PAL decks. Sometimes the game freezes randomly, sometimes it restarts, some others I lose any video output from the console desk. And those freezes occur when I've been playing 10 minuts, 50 minuts or a few seconds.
Since it sounded strange to me that the game runs fine on a Super Famicom, I recalled that Super Famicom has DC power inpunt, whereas PAL SNES has AC power input. I thought then that original boards have one capacitor around each chip on the board and then concluded that some AC power input noise was affecting +5V on my boards and made some data corrupt. This AC power noise was not present on Super Famicom and that was the reason the boards worked there. I used 10nF capacitors but... does anybody know which capacity have the ones found in the original boards? Do you think this decoupling capacitors are really necessary?
The fact is that those freezes have disappeared with the 10nF capacitors but the problem has been partially fixed: now sometimes the SNES reset itself again and I lose video output from the console, so I guess CIC's reset is being triggered, and that can only mean that SuperCIC is not giving the proper bit sequence and SNES lock CIC is resetting the CPU. However, this DOESN'T EVER happen on a Super Famicom, only in PAL SNES. What could be happening?
Maybe some noise coupled again on the PIC? Has anybody got some schematics with the proper PIC connection to the cartridge board?
Thanks!