Reset
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 4-15
4.4.3.5.2 Invalid RCHW
If the device is configured to boot from internal flash, a valid boot ID must be read at the lowest address
of one of the six LAS blocks in internal flash memory. If the device is configured to boot from external
memory, a valid boot ID must be read at 0x0000_0000 of CS[0]. Refer to Chapter 16, “Boot Assist Module
(BAM)” for more information.
If no valid RCHW is found, a serial boot is initiated which does not use the RCHW. The watchdog timer
is enabled. For serial boot entered from a failed external boot, the port size remains configured as 16-bits
wide. For serial boot entered from a failed internal boot, the external bus is never configured and remains
in the reset state of GPIO inputs.
4.4.3.5.3 Reset Configuration Halfword Source
The reset configuration halfword (RCHW) specifies a minimal MCU configuration after reset. The RCHW
also contains bits that control the BAM program flow. Refer to Section 16.3.2.2.5, “Read the Reset
Configuration Halfword” for information on the BAM using the RCHW. The RCHW is read and applied
each time the BAM program executes, which is for every power-on, external, or internal reset event. The
only exception to this is the software external reset.
Refer to Section 4.4.3.5, “Reset Configuration Halfword,” for detailed descriptions of the bits in the
RCHW. The RCHW is read from one of the following locations:
• The lowest address (0x0000_0000) of an external memory device, enabled by chip select CS[0]
using either a 16- or 32-bit data bus
• The lowest address of one of the six low address space (LAS) blocks in the internal flash memory.
(2 x 16K; 2 x 48K; 2 x 64K)
At the negation of the RSTOUT pin, the BOOTCFG field in the RSR has been updated. If BOOTCFG[0]
is asserted, then the BAM program reads the RCHW from address 0x0000_0000 in the external memory
connected to CS[0] (the BAM first configures the MMU and CS[0] such that address 0x0000_0000 is
translated to 0x2000_0000 and then directed to CS[0]). When BOOTCFG[0] is asserted, BOOTCFG[1]
determines whether external arbitration must be enabled to fetch the RCHW.
If BOOTCFG[0] and BOOTCFG[1] negates when RSTOUT
negates, the BAM program attempts to read
the RCHW from the first address of each of the six blocks in the low address space (LAS) of internal flash.
Table 4-9 shows the LAS addresses.
Table 4-9. LAS Block Memory Addresses
Block Address
0 0x0000_0000
1 0x0000_4000
2 0x0001_0000
3 0x0001_C000
4 0x0002_0000
5 0x0003_0000
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