
Crystal Trim
MOTOROLA
Signal Description
2-11
2.17
CRYSTAL TRIM
The XTRIM_GPO38 output produces a pulse-density modulated phase/frequency difference signal to be
used after low-pass filtering to control varicap-voltage to control crystal oscillation frequency. This will lock
the crystal to the incoming digital audio signal.
2.18
CLOCK OUT
The MCLK1/GPO39 and MCLK2/GPO42 can serve as general purpose I/Os or as DAC clock outputs.
When programmed as DAC clock outputs, these signals are directly divided from the crystal.
2.19
DEBUG AND TEST SIGNALS
These signals interface with external I/O to provide processor status signals.
2.19.1
TEST MODE
The TEST[3:0] inputs are used for various manufacturing and debug tests. For normal mode these inputs
should always be tied low. Use TEST0 to switch between background debug mode and JTAG mode. Drive
TEST0 high for debug mode.
2.19.2
HIGH IMPEDANCE
The assertion of HI_Z will force all output drivers to a high-impedance state. The timing on HI_Z is
independent of the clock.
Note: JTAG operation will override the HI_Z pin.
2.19.3
PROCESSOR CLOCK OUTPUT
The internal PLL generates this PSTCLK_GPO63 and output signal, and is the processor clock output that is
used as the timing reference for the Debug bus timing (DDATA[3:0] and PST[3:0]). The PSTCLK_GPO63 is
at the same frequency as the core processor and cache memory. The frequency will be twice the bus clock
(SCLK) frequency.
2.19.4
DEBUG DATA
The debug data pins, DDATA0_GPIO0, DDATA1_GPIO1, DDATA2_GPIO2, and DDATA3_GPIO4, are
four bits wide. This nibble-wide bus displays captured processor data and break-point status.
2.19.5
PROCESSOR STATUS
The processor status pins, PST0_GPIO59, PST1_GPIO60, PST2_GPIO61, and PST3_GPIO62, indicate
the MCF5249 processor status. During debug mode, the timing is synchronous with the processor clock
(PSTCLK) and the status is not related to the current bus transfer. Table 2-11 shows the encodings of
these signals.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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