External Bus Interface (EBI)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
29-15
Preliminary
29.3.2.7
EBI Option Registers 0–3 (EBI_ORn)
The EBI_OR
n
registers are used to define the address mask and other attributes for the corresponding chip
select.
Offset 0x0014 (EBI_OR0)
0x001C (EBI_OR1)
0x0024 (EBI_OR2)
0x002C (EBI_OR3)
Access: User read/write
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
R
1
1
1
AM
W
Reset
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
AM
0
0
0
0
0
0
0
SCY
0
BSCY
0
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Figure 29-6. EBI Option Registers 0–3 (EBI_ORn)
Table 29-8. EBI_ORn
Field
Description
AM
Address Mask. Allows masking of any corresponding bits in the associated base register. Masking the address
independently allows external devices of different size address ranges to be used. Any clear bit masks the
corresponding address bit. Any set bit causes the corresponding address bit to be used in comparison with the
address pins. Address mask bits can be set or cleared in any order in the field, allowing a resource to reside in
more than one area of the address map. This field can be read or written at any time.
Note: The upper three bits of the address mask (AM) field, EBI_ORx[0:2] are tied to a fixed value of 0b111.
These bits reset to their fixed value.
bits 17–23
Reserved.
SCY
Cycle Length in Clocks. Represents the number of wait states (external bus cycles) inserted after the address
phase in the single cycle case, or in the first beat of a burst, when the memory controller handles the external
memory access. Values range from 0 to 15. This is the main parameter for determining the length of the cycle.
These bits are ignored when SETA=1.
The total cycle length for the first beat (including the TS cycle):
See
Section 29.5.3.1, “Example Wait State Calculation
”.
(2 + SCY) external clock cycles