beautypg.com

2 chip mode selection, 2 chip mode selection -8 – Motorola ColdFire MCF5281 User Manual

Page 536

background image

Chip Configuration Module (CCM)

27-8

Freescale Semiconductor

27.6.2

Chip Mode Selection

The chip mode is selected during reset and reflected in the MODE field of the chip configuration register
(CCR). See

Section 27.5.3.1, “Chip Configuration Register (CCR)

.” Once reset is exited, the operating

mode cannot be changed.

Table 27-9

shows the mode selection during reset configuration.

CS0

RCON[4:3] = 00

RCON2 = 0

D[19:18]

Boot Device

00

Internal with 32-bit port

5

10

External with 8-bit port

01

External with 16-bit port

11

External with 32-bit port

All output pins

RCON5 = 1

D21

Output Pad Drive Strength

0

Partial strength

1

Full strength

5

Clock mode

N/A

CLKMOD1, CLKMOD0

Clock Mode

00

External clock mode (PLL disabled)

01

1:1 PLL mode

10

Normal PLL mode with external

clock reference

11

Normal PLL mode w/crystal reference

A[23:21]/CS[6:4]

RCON[9:8] = 00

D[25:24]

Chip Select Configuration

00

PF[7:5] = A[23:21]

5

10

PF[7] = CS6 / PF[6:5] = A[22:21]

01

PF[7:6] = CS6, CS5 / PF[5] = A[21]

11

PF[7:6] = CS6, CS5, CS4

1

Modifying the default configurations is possible only if the external RCON pin is asserted.

2

The D[31:27, 23:22, 20, 15:0] pins do not affect reset configuration.

3

The external reset override circuitry drives the data bus pins with the override values while RSTO is asserted. It must stop
driving the data bus pins within one CLKOUT cycle after RSTO is negated. To prevent contention with the external reset
override circuitry, the reset override pins are forced to inputs during reset and do not become outputs until at least one
CLKOUT cycle after RSTO is negated.

4

RCON[0] has higher priority than RCON[3:2]. When RCON[0] is configured to boot the chip in single chip mode, the part will
boot internally with a 32-bit port overriding any configuration set by RCON[3:2].

5

Default configuration

Table 27-8. Configuration During Reset

1

(continued)

Pin(s) Affected

Default

Configuration

Override Pins

in Reset

2,34

Function

MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3

This manual is related to the following products: