Hi there, I want to do a custom MMC1 4 in 1 cart that switches games when you hold reset for ~2 seconds. It essentially counts upwards and switches addresses A17 & A18 of PRG & CHR.
I used the same exact chip with the same exact program on SNES carts and they work perfectly fine but of course, SNES has /RESET line so everything is much easier to implement. I tried using the same exact chip with the same program but it barely works correctly as I expected. In addition, I added a 1N4148 diode + 102 cap as most reset based constructions suggest:
M2 CART ---|<|---+---PIC PIN #04
|
---
102
---
|
GND
It works quite randomly, when I randomly press or hold reset switch or turn the console on/off, the games randomly switch after 2 seconds of waiting but at least they only switch once and the console works perfectly fine during gameplay.
Can anyone explain what exactly the M2 signal behaves before, during and after reset is pressed?? How should I write the program to trigger game switch after holding reset for around 2 seconds. Why do I even need to add a diode with cap and should the diode cathode point straight to the cart connector or rather to the PIC chip?? Please for reply for any kind of suggestions. Many thanks in advance!!
I used the same exact chip with the same exact program on SNES carts and they work perfectly fine but of course, SNES has /RESET line so everything is much easier to implement. I tried using the same exact chip with the same program but it barely works correctly as I expected. In addition, I added a 1N4148 diode + 102 cap as most reset based constructions suggest:
M2 CART ---|<|---+---PIC PIN #04
|
---
102
---
|
GND
It works quite randomly, when I randomly press or hold reset switch or turn the console on/off, the games randomly switch after 2 seconds of waiting but at least they only switch once and the console works perfectly fine during gameplay.
Can anyone explain what exactly the M2 signal behaves before, during and after reset is pressed?? How should I write the program to trigger game switch after holding reset for around 2 seconds. Why do I even need to add a diode with cap and should the diode cathode point straight to the cart connector or rather to the PIC chip?? Please for reply for any kind of suggestions. Many thanks in advance!!