Maxim Integrated MAXQ622 - Manual (Page 13)

MAXQ612/MAXQ622 User’s Guide
Maxim Integrated 2-9
2.5.1 Memory Mapping Into Data Space
The MAXQ612/MAXQ622 map program memory into data space from 0000h to FFFFh . The selection of physical pro-
gram memory page or pages to be logically mapped to data space is determined by the CDA1 and CDA0 bits, as
shown in Table 2-2 .
Figure 2-3 summarize the default memory maps for this memory structure . The WBSn bits of the MAXQ612/MAXQ622
default to word access mode (WBSn = 1) .
The upper half of the data memory map (8000h to FFFFh) is the logical area for the utility ROM when accessed as
data . Executing code from the utility ROM allows the user to map the program memory to 8000h to FFFFh by properly
selecting the CDA bits .
Figure 2-4 and 2-5 illustrate the effects of the CDA bits .
Figure 2-3. MAXQ612/MAXQ622 Memory Map (64KB Program Space)
Table 2-2. CDA Bits to Access Program Space as Data
PROGRAM
SPACE
88FFh
FFFFh
0000h
8000h
3K x 16
UTILITY ROM
x 8
DATA SRAM
x 16
DATA SRAM
64K x 16
PROGRAM FLASH
DATA SPACE
(BYTE MODE)
DATA SPACE
(WORD MODE)
0000h
17FFh
0000h
08FFh
CDA[1:0] SELECTED PAGE IN BYTE MODE SELECTED PAGE IN WORD MODE
00 P0 P0 and P1
01 P1 P0 and P1
10 P2 P2 and P3
11 P3 P2 and P3