Rainbow Electronics AT75C220 - Manual (Page 19)

AT75C220
19
SMC Register Map
The SMC is programmed using the registers listed in the
Table 8. The memory control register (SMC_MCR) is used
to program the number of active chip selects and data read
protocol. Four chip select registers (SMC_CSR0 to
SMC_CSR3) are used to program the parameters for the individual external memories. Each SMC_CSR must be
programmed with a different base address, even for
unused chip selects. The AT75C220 resets such that
SMC_CSR0 is configured as having a 16-bit data bus.
SMC Chip Select Register
Register Name:SMC_CSR0..SMC_CSR3
Access:
Read/write
Reset Value:
• DBW: Data Bus Width
Table 8. SMC Register Map
Offset Register Name Description Access Reset Value
0x00 SMC_CSR0 Chip Select Register Read/write 0x0000203D
0x04 SMC_CSR1 Chip Select Register Read/write 0x10000000
0x08 SMC_CSR2 Chip Select Register Read/write 0x20000000
0x0C SMC_CSR3
Chip Select Register
Read/write 0x30000000
0x10 – Reserved – –
0x14 – Reserved – –
0x18 – Reserved – –
0x1C – Reserved – –
0x20 – Reserved – –
0x24 SMC_MCR Memory Control Register Read/ write 0
31 30 29 28 27 26 25 24
BA
23 22 21 20 19 18 17 16
BA – – – LCD
15 14 13 12 11 10 9 8
– – CSEN BAT TDF PAGES
7 6 5 4 3 2 1 0
PAGES MWS WSE NWS DBW
DBW Data Bus Width
0 0 Reserved
0 1 16-bit external bus
1 0 32-bit external bus
1 1 Reserved