Processor Users Manual

MOTOROLA Chapter 5. Reset 5-7
Part II. ConÞguration and Reset
Table 5-6 shows addresses that should be used to conÞgure the various MPC8260s. Byte
addresses that do not appear in this table have no effect on the conÞguration of the
MPC8260 chips. The values of the bytes in Table 5-6 are always read on byte lane D[0Ð7]
regardless of the port size.
The conÞguration master Þrst reads a value from address 0x00 then reads a value from
addresses 0x08, 0x10, and 0x18. These four bytes are used to form the conÞguration word
of the conÞguration master, which then proceeds reading the bytes that form the
conÞguration word of the Þrst slave device. The conÞguration master drives the whole
conÞguration word on D[0Ð31] and toggles its A0 address line. Each conÞguration slave
uses its RSTCONF
input as a strobe for latching the conÞguration word during HRESET
assertion time. Thus, the Þrst conÞguration slave whose RSTCONF input is connected to
conÞguration masterÕs A0 output latches the word driven on D[0Ð31] as its conÞguration
word. In this way the conÞguration master continues to conÞgure all MPC8260 chips in the
system. The conÞguration master always reads eight conÞguration words regardless of the
number of MPC8260 parts in the system. In a simple system that uses one stand-alone
MPC8260, it is possible to use the default hard reset conÞguration word (all zeros). This is
done by tying RSTCONF
input to VCC. Another scenario may be a system which has no
boot EPROM. In this case the user can conÞgure the MPC8260 as a conÞguration slave by
driving RSTCONF
to 1 during PORESET assertion and then applying a negative pulse on
RSTCONF
and an appropriate conÞguration word on D[0Ð31]. In such a system, asserting
HRESET
in the middle of operation causes the MPC8260 to return to the conÞguration
programmed after PORESET
assertion (not the default conÞguration represented by
conÞguration word of all zeros).
Table 5-6. Configuration EPROM Addresses
ConÞgured Device Byte 0 Address Byte 1 Address Byte 2 Address Byte 3 Address
ConÞguration master 0x00 0x08 0x10 0x18
First conÞguration slave 0x20 0x28 0x30 0x38
Second conÞguration slave 0x40 0x48 0x50 0x58
Third conÞguration slave 0x60 0x68 0x70 0x78
Fourth conÞguration slave 0x80 0x88 0x90 0x98
Fifth conÞguration slave 0xA0 0xA8 0xB0 0xB8
Sixth conÞguration slave 0xC0 0xC8 0xD0 0xD8
Seventh conÞguration slave 0xE0 0xE8 0xF0 0xF8