Maxim Integrated High-Speed Microcontroller Users Guide: Network Microcontroller Supplement - Manual (Page 99)

DS80C410/DS80C411
Similar to the DS80C400, the DS80C410 and DS80C411 incorporate three internal SRAM memory blocks: a 1kB block usable as data
memory and extended stack memory, a 64kB block usable as data memory and Ethernet transmit/receive buffer memory, and a 256-
byte block usable as data memory and CAN controller memory. For the 1kB internal SRAM to be used as extended stack memory, the
stack address mode (SA) bit contained in the ACON register must be set to 1. Unlike the DS80C400, the logical addresses of these
blocks are fixed, as follows:
CAN SRAM (256 byte): FFDB00h–FFDBFFh
Data/Extended Stack (1kB) FFDC00h–FFDFFFh
Internal Data memory (64kB) 0000000h–00FFFFh
The 64kB memory block can be enabled or disabled by the Internal RAM Disable bit, IRAMD (MCON1.7). When enabled, the 64kB
memory block appears in the MOVX address space at locations 0000000h–00FFFFh. All MOVX memory operations in that range auto-
matically access internal memory, and no external memory signals (address bus, RD or WR strobes) are active. When disabled, all
MOVX memory operations over that range are directed onto the external bus and the internal locations are ignored.
The DS80C410/411 incorporate a new feature that allows the 64kB memory block to be mapped from data into program memory
space. The Program RAM Enable bit, PRAME (MCON1.6) controls whether the 64kB memory block, if enabled by the IRAMD bit, will
either be located at 0000000h–00FFFFh in data space or program space. This very useful feature allows the designer to create self-
modifying code by using MOVC instructions to read existing code space into the 64kB data memory block, modify it, and then use the
PRAME bit to map the 64kB block back into program memory space. These features are illustrated in Figure 6-3.
High-Speed Microcontroller User’s
Guide: Network Microcontroller
Supplement
99
Figure 6-3. Example Data Memory Map Configurations (DS80C410/DS80C411)
Addressable
External
Data Memory
IRAMD = 1, PRAME = X
Internal 8kB SRAM
(Ethernet BCU)
FFFFFFh
Internal 1kB SRAM
(Optional Stack)
FFE000h
FFDFFFh
FFDC00h
FFDBFFh
FFDB00h
FFDAFFh
000000h
256 Byte SRAM
(CAN)
Addressable
External
Data Memory
Internal 65kB
Data SRAM
IRAMD = 0, PRAME = 0
* This memory should not be
accessed on the DS80C411.
* This memory should not be
accessed on the DS80C411.
Internal 8kB SRAM
(Ethernet BCU)
FFFFFFh
Internal 1kB SRAM
(Optional Stack)
FFE000h
FFDFFFh
FFDC00h
FFDBFFh
FFDB00h
FFDAFFh
010000h
00FFFFh
000000h
010000h
00FFFFh
256 Byte SRAM*
(CAN)
Addressable
External
Data Memory
Internal merged
64kB Data
and Program SRAM
Internal 8kB SRAM
(Ethernet BCU)
Internal 1kB SRAM
(Optional Stack)
256 Byte SRAM*
(CAN)
IRAMD = 0, PRAME = 1
FFFFFFh
FFE000h
FFDFFFh
FFDC00h
FFDBFFh
FFDB00h
FFDAFFh
000000h
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