C8051F93X Datasheet, PDF (122/330 Pages) Silicon Laboratories – Pipelined intstruction architecture executes 70 of instruction in 1 or 2 system clocks

C8051F93x-C8051F92x
10.7. EMIF Special Function Registers
The special function registers used by the EMIF are EMI0CN, EMI0CF, and EMI0TC. These registers are
described in the following register descriptions.
SFR Definition 10.1. EMI0CN: External Memory Interface Control
Bit
7
6
5
4
3
2
1
0
Name
PGSEL[4:0]
Type
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset
0
0
0
0
0
0
0
0
SFR Page = 0x0; SFR Address = 0xAA
Bit Name
Function
7:5 Unused Unused.
Read = 000b; Write = Don’t Care
4:0 PGSEL XRAM Page Select.
The EMI0CN register provides the high byte of the 16-bit external data memory
address when using an 8-bit MOVX command, effectively selecting a 256-byte page
of RAM. Since the upper (unused) bits of the register are always zero, the PGSEL
determines which page of XRAM is accessed. When the MSB of PGSEL is set to 1
and the EMIF is configured for one of the two split-modes, 8-bit MOVX instructions
target off-chip memory.
For Example:
If EMI0CN = 0x01, addresses 0x0100 through 0x01FF of on-chip memory will be
accessed.
If EMI0CN = 0x0F, addresses 0x0F00 through 0x0FFF of on-chip memory will be
accessed.
If EMI0CN = 0x11, addresses 0x0100 through 0x01FF of off-chip memory will be
accessed.
If EMI0CN = 0x1F, addresses 0x0F00 through 0x0FFF of off-chip memory will be
accessed.
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