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Chapter 5 Microcontroller Boot
MPC5606BK Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor
75
Chapter 5
Microcontroller Boot
This chapter explains the process of booting the microcontroller. The following entities are involved in the
boot process:
•
•
System Status and Configuration Module (SSCM)
•
Flash memory boot sectors (see
)
•
Memory Management Unit (MMU)
5.1
Boot mechanism
This section describes the configuration required by the user, and the steps performed by the
microcontroller, in order to achieve a successful boot from flash memory or serial download modes.
Two external pins on the microcontroller are latched during reset, and determine whether the
microcontroller boots from flash memory or attempt a serial download via FlexCAN or LINFlex (RS232).
These are:
•
FAB (Force Alternate Boot mode) on pin PA[9]
•
ABS (Alternate Boot Select) on pin PA[8]
describes the configuration options.
The microcontroller has a weak pulldown on PA[9] and a weak pullup on PA[8]. This means that if nothing
external is connected to these pins, the microcontroller will enter flash memory boot mode by default. In
order to change the boot behavior, you should use external pullup or pulldown resistors on PA[9] and
PA[8]. If there is any external circuitry connected to either pin, you must ensure that this does not interfere
with the expected value applied to the pin at reset. Otherwise, the microcontroller may boot into an
unexpected mode after reset.
The SSCM preforms a lot of the automated boot activity including reading the latched value of the FAB
(PA[9]) pin to determine whether to boot from flash memory or serial boot mode. This is illustrated in
.
Table 5-1. Boot mode selection
Mode
FAB pin (PA[9])
ABS pin (PA[8])
Flash memory boot (default mode)
0
X
Serial boot (LINFlex)
1
0
Serial boot (FlexCAN)
1
1
Summary of Contents for MPC5605BK
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Page 20: ...MPC5606BK Microcontroller Reference Manual Rev 2 20 Freescale Semiconductor...
Page 103: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 103 Clocks and power...
Page 645: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 643 Timers...
Page 715: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 713 ADC system...
Page 787: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 787 Memory...
Page 893: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 893 Integrity...
Page 943: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 943 Debug...