C8051F411EK Silicon Laboratories Inc, C8051F411EK Datasheet - Page 145

• Manufacturer Part Number: C8051F411EK
• Description: KIT EVAL FOR C8051F411
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F411EK

• Contents: Evaluation Board, CD-ROM, USB Cable, Batteries and User Guide
• Processor To Be Evaluated: C8051F41x
• Interface Type: USB
• Silicon Manufacturer: Silicon Labs
• Core Architecture: 8051
• Silicon Core Number: C8051F411
• Silicon Family Name: C8051F41x
• Kit Contents: LCD Based Evaluation Board, USB Cable, Software CD And Quick-Start Guide
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Silicon Laboratories C8051F41x
• For Use With: 336-1315 - KIT REF DESIGN VOICE RECORD F41X
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1317

17. External RAM
The C8051F41x devices include 2048 bytes of RAM mapped into the external data memory space. All of
these address locations may be accessed using the external move instruction (MOVX) and the data
pointer (DPTR), or using MOVX indirect addressing mode. If the MOVX instruction is used with an 8-bit
address operand (such as @R1), then the high byte of the 16-bit address is provided by the External Mem-
ory Interface Control Register (EMI0CN as shown in SFR Definition 17.1). Note: the MOVX instruction is
also used for writes to the Flash memory. See
MOVX instruction accesses XRAM by default.
For a 16-bit MOVX operation (@DPTR), the upper 5-bits of the 16-bit external data memory address word
are "don't cares.” As a result, the RAM is mapped modulo style over the entire 64 k external data memory
address range. For example, the XRAM byte at address 0x0000 is shadowed at addresses 0x0800,
0x1000, 0x1800, 0x2000, etc. This is a useful feature when performing a linear memory fill, as the address
pointer doesn't have to be reset when reaching the RAM block boundary.
Bits 7–3: UNUSED. Read = 00000b. Write = don’t care.
Bits 2–0: PGSEL: XRAM Page Select.
R/W
Bit7
-
SFR Definition 17.1. EMI0CN: External Memory Interface Control
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.
For Example: If EMI0CN = 0x01, addresses 0x0100 through 0x01FF will be accessed.
R/W
Bit6
-
R/W
Bit5
-
R/W
Bit4
-
Section “16. Flash Memory” on page 135
Rev. 1.1
R/W
Bit3
-
R/W
Bit2
C8051F410/1/2/3
PGSEL
R/W
Bit1
SFR Address:
R/W
Bit0
for details. The
0xAA
00000000
Reset Value
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