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Hi, I work on ST10F168 and i use external ram by EBC in 16 bits demux mode with keil V2.38 There are 4 Chip Select available for ram : CS1,CS2,CS3,CS4 and 23 adress bits : A1->A23 So, there are (2^23 * 4) bytes accessible <=> 32Mo I would to know if i am right and if i can declare an external memory map of 32 Mo ! Thanks for any suggestions ! Regards, Jim
Can i switch a 16Mo page with a simple bit use like chip select between 2 page of 16Mo (for example P3^5) Exactly. This is the so called bank switching. Remember that not exactly 16M bytes are accessisble via the external bus: 4K bytes are mapped to on-chip RAM and SFRs and 8K bytes are mapped to XRAM and CAN registers. So it's more like 16M-12K bytes, or even less with on-chip ROM (256K bytes) enabled. If you don't want to waste a byte, you could have 4 banks 8M bytes each. - mike
Hi, I would to know if the capacity of external memory is 16M*8bits, 16Mo*16bits or the twice are good . Thanks Regards, Jim
Not sure what you mean there, but I'll try to answer anyway. The size of the address space is 16M bytes. That means that you can't address more than that directly (without bank switching). You can address slightly less than 16M bytes via the external bus. You can address more with bank switching, as discussed earlier. 16M x 8 bits is 16M bytes. 16M x 16 bits is 32M bytes. - mike
Thanks