MCF52221 datasheet(21/56 Pages) FREESCALE

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MCF52223 Family Configurations

MCF52223 ColdFire Microcontroller, Rev. 2

Freescale Semiconductor

1.3

Reset Signals

Table 3 describes signals used to reset the chip or as a reset indication.

1.4

PLL and Clock Signals

Table 4 describes signals used to support the on-chip clock generation circuitry.

1.5

Mode Selection

Table 5 describes signals used in mode selection; Table 6 describes the particular clocking modes.

Table 3. Reset Signals

Signal Name

Abbreviation

Function

I/O

Reset In

RSTI

Primary reset input to the device. Asserting RSTI for at least 8 CPU

clock cycles immediately resets the CPU and peripherals.

Reset Out

RSTO

Driven low for 1024 CPU clocks after the reset source has deasserted.

Table 4. PLL and Clock Signals

Signal Name

Abbreviation

Function

I/O

External Clock In

EXTAL

Crystal oscillator or external clock input except when the on-chip

relaxation oscillator is used.

Crystal

XTAL

Crystal oscillator output except when CLKMOD1=1, then sampled as

part of the clock mode selection mechanism.

Clock Out

CLKOUT

This output signal reflects the internal system clock.

Table 5. Mode Selection Signals

Signal Name

Abbreviation

Function

I/O

Clock Mode Selection

CLKMOD[1:0]

Selects the clock boot mode.

Reset Configuration

RCON

The Serial Flash Programming mode is entered by asserting the

RCON pin (with the TEST pin negated) as the chip comes out of

reset. During this mode, the EzPort has access to the flash memory

which can be programmed from an external device.

Test

TEST

Reserved for factory testing only and in normal modes of operation

should be connected to VSS to prevent unintentional activation of

test functions.

Table 6. Clocking Modes

CLKMOD[1:0]

XTAL

Configure the clock mode.

PLL disabled, clock driven by external oscillator

PLL disabled, clock driven by on-chip oscillator

N/A

PLL disabled, clock driven by crystal

PLL in normal mode, clock driven by external oscillator

PLL in normal mode, clock driven by on-chip oscillator

N/A

PLL in normal mode, clock driven by crystal

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