Reset
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
11-3
The following sections describe the events that can initiate an internal assertion of HRESET and SRESET.
11.1.3.1
Software Watchdog Reset
When the core watchdog counter decrements to zero, a software watchdog reset is asserted generating an
internal hard reset sequence. Note that this is the default response; that is, an NMI to the core can be issued
instead of a hard reset, and the timer can be disabled. See
Section 10.7, “Software Watchdog Timer.”
11.1.3.2
Checkstop Reset
If the core enters a checkstop state and PLPRCR[CSR] = 1, the checkstop reset is asserted generating an
internal hard reset sequence. See
Section 14.6.2, “PLL and Reset Control Register (PLPRCR).”
11.1.4
Debug Port Hard or Soft Reset
When the development port receives a hard or soft reset request from a development tool, an internal hard
or soft reset sequence is generated. The development tool must reconfigure the debug port following a reset
event. See
Section 53.3.2.1.2, “Development Serial Data In (DSDI).”
11.1.5
JTAG Reset
When the JTAG logic asserts the JTAG reset signal, an internal soft reset sequence is generated.
11.1.6
Power-On and Hard Reset Sequence
Figure 11-1
shows the reset sequence following a power-on or internal or external hard reset event.
Figure 11-1. Power-On and Hard Reset Sequence
Power-On
Reset
Internally
Wait
Initiated
HRESET
Power On
Internal or External
HRESET Asserted
• Sample MODCK pins and initialize clocks
• HRESET and SRESET are asserted
• HRESET and SRESET assert
• The time counter is set to 512
• Sample configuration from data pins
• Negate HRESET and SRESET
• Wait for 16 clocks
• Test for HRESET or SRESET
Start Normal Operation
PORESET is Negated and PLL Lock
Timer Expires (After 512 Clocks)
16 Clocks Expire
External HRESET
Asserted
(From system reset interrupt exception vector)
Summary of Contents for PowerQUICC MPC870
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