MAC7200 datasheet(431/976 Pages) FREESCALE

431 / 976 page

FlexBus Application Usage

MAC7200 Microcontroller Family Reference Manual, Rev. 2

Freescale Semiconductor

353

•

The mix of external bus signals available at pins is different from the MAC71x1 to the MAC72xx.

•

Fixed MUCts01460: Thumb mode accesses have incorrect address and/or byte selects

17.7

FlexBus Application Usage

17.7.1

Enabling the FlexBus

It is not necessary to enable the FlexBus before it can be used. Please see Section 17.7.2, “Global Chip

Select Mode below for more information on the behavior of the FlexBus out of reset.

17.7.2

Global Chip Select Mode

After reset, the FlexBus is put into a Global Chip Select Mode, where all external bus accesses map to CS0.

This allows the maximum flexibility to boot from external sources before the FlexBus is configured. The

configuration of CS0 in Global Chip Select Mode is as follows:

To exit Global Chip select mode, set the Valid bit in the CSMR0 register. The only possibility to enter

Global Chip Select mode again after that is a Reset. Until Global Chip Select Mode is exited, all chip

selects, other than CS0, are unavailable. Outside of Global Chip Select mode, the CS0 registers behave

identically to all other chip select registers.

When modifying the configuration of a chip select, it is generally recommended to first clear the Valid bit

for that chip select in order to avoid possible race conditions between external bus accesses and

Table 17-11. Global Chip Select Mode Configuration

Field Values at Reset

CSAR0

0x0000_0000

CSMR0

0x0000_0000

CSCR0

SWS[31:26] = 0x00

SWSEN[23] = 0

ASET[21:20] = 11

RDAH[19:18] = 11

WRAH[17:16] = 11

WS[15:10] = 0x3f (63 wait states)

MUX[9] = 0

AA[8] = from pin PF2

PS1[7] = from pin PF3

PS0[6] = 1

BEM[5] = 0

BSTR[4] = 0

BSTW[3] = 0

MAC7200 Datasheet(PDF) 431 Page - Freescale Semiconductor, Inc

MAC7200 Datasheet(HTML) 431 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL