Add feature to a cart
Posted: Wed Dec 23, 2015 11:30 am
Hi,
It's something I really like to be able for a long time but I lack knowledge : how to add feature to a cart ?
Don't worry, I don't want to create a game with 32Mo rom, mp3 support or whatever, it's for debugging purpose.
From db-elec, I know I should not consume more than 100ma
(viewtopic.php?f=13&t=1931)
From an old post, I know I could power the extra 'layer' if ground is shared
(viewtopic.php?p=15138#p15138)
From current SRAM thread, I learnt more details
(viewtopic.php?f=2&p=28229)
From an old post by Eke, it seems we can, in fact, write to any address. The write signal is used to make the diff between ROM and others .... but read isn't possible in that case, right ?
(viewtopic.php?p=12645#p12645)
What I miss is how to communicate with my extra layer ?
Let see severals level of 'feature'
- SRAM:
* doesn't need extra power
* direct connection
* 8bit (odd or even from the 16 bit data bus)
* use VA21, so limit max ROM size
- SRAM (serial):
* doesn't need extra power
* serial comm on an unique adress (0x200001 for ex)
* direct connection
* use VA21, so limit max ROM size
J Cart
* eeprom and additionnal io share the same adresse
(https://github.com/ekeeke/Genesis-Plus- ... i2c.c#L809)
- SSF2
* mapper to switch part of memory
- lock on
* CPLD ?
- Virtua Racing
* doesn't need extra power
* add a dedicated IC
* use its own memory map
- UMDK :
* add an IC
* powered by usb
* no communication
* data protection using buffer (so no direct connection)
* no memory shared (IC can't access to MD memory)
- SMD
* add a CPLD
* powered by cart
* share memory
- Channel / X Band
* complex sys on a cart !
- 32X
* ....WOW
So, if I want to add an AVR on a cart and to control, from it, several others modules (ex: bluetooth for faster serial transfert)
how could I power it ?
how could I communicate with it , with a minimal of GPIO pin use and a small address map ?
how could the AVR access to MD memory (joy included) ?
To avoid the 3.3v / 5v debate, I'll use a 5V avr, don't know if I'll use 3.3V modules yet...
I think an AVR powered from its own (smartphone usb) adapter using the SRAM comm and address could be used but what if I need more ?
any project to share ?
(another way was to use the ext port, like the modem, but it's slow and even more limited)
It's something I really like to be able for a long time but I lack knowledge : how to add feature to a cart ?
Don't worry, I don't want to create a game with 32Mo rom, mp3 support or whatever, it's for debugging purpose.
From db-elec, I know I should not consume more than 100ma
(viewtopic.php?f=13&t=1931)
From an old post, I know I could power the extra 'layer' if ground is shared
(viewtopic.php?p=15138#p15138)
From current SRAM thread, I learnt more details
(viewtopic.php?f=2&p=28229)
From an old post by Eke, it seems we can, in fact, write to any address. The write signal is used to make the diff between ROM and others .... but read isn't possible in that case, right ?
(viewtopic.php?p=12645#p12645)
What I miss is how to communicate with my extra layer ?
Let see severals level of 'feature'
- SRAM:
* doesn't need extra power
* direct connection
* 8bit (odd or even from the 16 bit data bus)
* use VA21, so limit max ROM size
- SRAM (serial):
* doesn't need extra power
* serial comm on an unique adress (0x200001 for ex)
* direct connection
* use VA21, so limit max ROM size
J Cart
* eeprom and additionnal io share the same adresse
(https://github.com/ekeeke/Genesis-Plus- ... i2c.c#L809)
- SSF2
* mapper to switch part of memory
- lock on
* CPLD ?
- Virtua Racing
* doesn't need extra power
* add a dedicated IC
* use its own memory map
- UMDK :
* add an IC
* powered by usb
* no communication
* data protection using buffer (so no direct connection)
* no memory shared (IC can't access to MD memory)
- SMD
* add a CPLD
* powered by cart
* share memory
- Channel / X Band
* complex sys on a cart !
- 32X
* ....WOW
So, if I want to add an AVR on a cart and to control, from it, several others modules (ex: bluetooth for faster serial transfert)
how could I power it ?
how could I communicate with it , with a minimal of GPIO pin use and a small address map ?
how could the AVR access to MD memory (joy included) ?
To avoid the 3.3v / 5v debate, I'll use a 5V avr, don't know if I'll use 3.3V modules yet...
I think an AVR powered from its own (smartphone usb) adapter using the SRAM comm and address could be used but what if I need more ?
any project to share ?
(another way was to use the ext port, like the modem, but it's slow and even more limited)