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Hardware > multiplexed bus of GBA

#8049 - DJF - Tue Jul 01, 2003 6:42 am

HI everybody
GBA games use a multiplexed bus at 3V, but I do not know how it works,
Who can tell me how to determine the data on AD0-AD15 is address or data? Thank you.

#8052 - tepples - Tue Jul 01, 2003 8:20 am

DJF wrote:
HI everybody
GBA games use a multiplexed bus at 3V, but I do not know how it works,
Who can tell me how to determine the data on AD0-AD15 is address or data? Thank you.

Reiner Ziegler's GBA page will tell you everything you always wanted to know about the GBA's connectors[1].

Summary: When /CS goes low, latch the 24-bit address and read one 16-bit word from flash into the cart's output buffer. When /RD goes low, put the cart's output buffer on the bus, and when /RD goes back high, increment the latched address and read another 16-bit word from flash. Preferably, use 100ns flash.

[1] but were afraid to ask
_________________
-- Where is he?
-- Who?
-- You know, the human.
-- I think he moved to Tilwick.

#8103 - DJF - Wed Jul 02, 2003 3:41 am

tepples wrote:
DJF wrote:
HI everybody
GBA games use a multiplexed bus at 3V, but I do not know how it works,
Who can tell me how to determine the data on AD0-AD15 is address or data? Thank you.

Reiner Ziegler's GBA page will tell you everything you always wanted to know about the GBA's connectors[1].

Summary: When /CS goes low, latch the 24-bit address and read one 16-bit word from flash into the cart's output buffer. When /RD goes low, put the cart's output buffer on the bus, and when /RD goes back high, increment the latched address and read another 16-bit word from flash. Preferably, use 100ns flash.

[1] but were afraid to ask


Thank you for your answer, I understand it now.