Mapping externe: Code:EPROM 00000--01FFF Code:RAM 12000--1FFFF Data:RAM 02000--0F6FF External logic manage the A16 line of RAM chip: - A16=1 on falling edge of ALE - A16=0 when RD or WR = 0 My code is stored in 2 I2C eeprom. The Boot code download it in upper RAM (A16 force to 1), then goes in automatic mode described before. Every things seams ok (sumckeck test works...) BUT I have a very strange behaviour: one program (A prog) works and another one (B prog) doesn't work. The only difference between them is local variable of a function. The A prog has int myVar; and the B has int idata myVar; My target is a C505CA from infineon and I use the small model. My internal ramsize is 256. I have check in detail the both M51 file the overlay of memory. It seams to be ok. To be sure that A prog works correctly I need to check two things: 1) my hardware solution 2) why the affectation of idata in local variable generates troubles
to resume: C505CA, 12MHz, RAM 70ns PSEN pulse = 125ns RD or WR pulse = 250ns
-------- 1-------|D Q|------A16ram ALEc505--------o|CLK | | | RD/and WR/c505--|CLR | --------