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MC68000 chip select

Question asked by Prasadh Teppala on Oct 5, 2018
Latest reply on Oct 9, 2018 by Fang Li

Hi All,



Currently I am working on MC68360 processor to enable the chip select 7. I am setting the Base register and Option register with the values 0x02010001 and 0xFFFFF004 respectively, But after turning on the board, I am not able to see the CS7 toggling.


Memory Map: 0x00000000 to 0xFFFFFFFF

SRAM Bank for CS7: 0x02010000 to 0x02011000

SRAM Bank for CS5: 0x02000000 to 0x02000800


Registers Address:

MBAR    EQU     $03FF00

PEPAR   EQU     $031016

GMR     EQU     $031040

BR7     EQU     $0310C0

OR7     EQU     $0310C4

MBAR code: 

moveq.l #7,d0 ; "0111" is the function code for CPU Space
movec d0,SFC ; Store "0111" into both the Src Fcn Code Reg
movec d0,DFC ; and the Dest. Fcn Code Reg
moves.l MBAR,d0 ; load MBAR value into d0
andi.l #$FFFFE000,d0 ; mask lower 13 bits
move.l d0,a5 ; save base address in a5


Port E assignment: MOVE.W    #$0094,PEPAR

Global Memory Register (GMR): MOVE.L    #$00001200,GMR

OR5 : MOVE.L    #$FFFF0004,OR5

BR5 : MOVE.L    #$02000001,BR5

OR7 : MOVE.L    #$FFFFF004,OR7

BR7 : MOVE.L    #$02010001,BR7

currently on CS7, no hardware connected.


We had configured registers for chip selects 0-6, thay all working. The CS7 we are trying to enable is not working. 

When we swapped BR5 and OR5 with BR7 and OR7, then CS7 working but CS5 is not working.


Please help me. Thank you.