System Integration Unit (SIU)
Freescale Semiconductor
7-5
PXR40 Microcontroller Reference Manual, Rev. 1
7.2.1.2
Reset Output (RSTOUT)
RSTOUT is an active-low output signal that uses a push/pull configuration. It is driven to the low state by
the MCU for all internal and external reset sources. After the RESET input signal negates, RSTOUT
asserts for:
•
16000 clock cycles for devices configured in bypass mode
•
2400 clock cycles for all other FMPLL modes
To invoke an external software reset, write a 1 to the system external reset (SER) bit in the system reset
control register (SIU_SRCR). This asserts RSTOUT for 2400 clock cycles. An external software reset
does not execute the BAM module or sample BOOTCFG[0:1].
7.2.1.3
General-Purpose I/O (GPIOn)
The GPIO signals provide general-purpose input and output functions. GPIO signals are generally
multiplexed with other I/O pin functions. Each GPIO input and output is separately controlled by an
eight-bit general-purpose data input (SIU_GPDI
n
) and a general-purpose data output (SIU_GPDO
n
)
register.
The SIU also implements several parallel GPIO registers (SIU_PGPDO
x_x
and SIU_PGPDI
x_x
) that can
be used to access up to 32 GPIO bits in a single- and word-sized accesses. The values read/written to these
parallel registers are coherent with the data read/written to the SIU_GPDO
x
_
x
and
SIU_GPDI
x_x
registers
Refer to the following sections for more information:
Section 7.3.1.14, GPIO Pin Data Output Registers 0–512 (SIU_GPDOn)
Section 7.3.1.15, GPIO Pin Data Input Registers 0–255 (SIU_GPDIn)
7.2.1.4
Boot Configuration (BOOTCFG[0:1])
The BOOTCFG value specifies the location and boot mode used by the boot assist module (BAM). All
reset sources can read the boot configuration field, BOOTCFG[0:1], except a debug port reset and a
software external reset.
BOOTCFG[0:1] is sampled while processing a reset. The BOOTCFG values are used only while RSTOUT
is asserted. Otherwise, the default value for BOOTCFG (0b00) in the reset status register (SIU_RSR) is
used, as shown in
Table 7-4. BOOTCFG Configuration
BOOTCFG[0]
BOOTCFT[1]
Meaning
0
0
Boot from internal flash memory (default)
0
1
FlexCAN / eSCI boot
1
0
Boot from external memory (no arbitration)
1
1
Boot from external memory (external arbitration)
–EBI not available on all packages
Summary of Contents for PXR4030
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Page 30: ...PXR40 Microcontroller Reference Manual Rev 1 Freescale Semiconductor xxx...
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