18.4.2 EMI0CF: External Memory Configuration
Bit
7
6
5
4
3
2
1
0
Name
Reserved
EMD
EALE
Access
RW
RW
RW
Reset
0x0
0x0
0x3
SFR Page = 0x0; SFR Address: 0xAB
Bit
Name
Reset
Access
Description
7:4
Reserved
Must write reset value.
3:2
EMD
0x0
RW
EMIF Operating Mode Select.
Value
Name
Description
0x0
INTERNAL_ONLY
Internal Only: MOVX accesses on-chip XRAM only. All effective addresses alias
to on-chip memory space.
0x1
SPLIT_WITH-
OUT_BANK_SELECT
Split Mode without Bank Select: Accesses below the internal XRAM boundary are
directed on-chip. Accesses above the internal XRAM boundary are directed off-
chip. 8-bit off-chip MOVX operations use the current contents of the Address high
port latches to resolve the upper address byte. To access off chip space, EMI0CN
must be set to a page that is not contained in the on-chip address space.
0x2
SPLIT_WITH_BANK_S
ELECT
Split Mode with Bank Select: Accesses below the internal XRAM boundary are di-
rected on-chip. Accesses above the internal XRAM boundary are directed off-
chip. 8-bit off-chip MOVX operations uses the contents of EMI0CN to determine
the high-byte of the address.
0x3
EXTERNAL_ONLY
External Only: MOVX accesses off-chip XRAM only. On-chip XRAM is not visible
to the core.
1:0
EALE
0x3
RW
ALE Pulse-Width Select.
These bits only have an effect when the EMIF is in multiplexed mode (MUXMD = 0).
Value
Name
Description
0x0
1_CLOCK
ALE high and ALE low pulse width = 1 SYSCLK cycle.
0x1
2_CLOCKS
ALE high and ALE low pulse width = 2 SYSCLK cycles.
0x2
3_CLOCKS
ALE high and ALE low pulse width = 3 SYSCLK cycles.
0x3
4_CLOCKS
ALE high and ALE low pulse width = 4 SYSCLK cycles.
EFM8SB2 Reference Manual
External Memory Interface (EMIF0)
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