Maxim-integrated MAXQ622 Manual do Utilizador descarregar pdf (Página 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

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 ... 254 255

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Maxim-integrated MAXQ622 Manual do Utilizador Página 13