External Bus Interface (EBI)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
29-16
Freescale Semiconductor
Preliminary
29.4
Functional Description
29.4.1
External Bus Interface Features
29.4.1.1
Multiplexed 32-bit Address/Data Bus (Single Master)
This is the default mode of operation for MPC5510. See
Section 29.1.3.6, “Multiplexed Address on Data
.” A 16-bit data bus mode is available via the DBM bit in EBI_MCR. See
.”
29.4.1.2
Memory Controller with Support for Various Memory Types
The EBI contains a memory controller that supports a variety of memory types, including synchronous
burst mode flash and external SRAM, and asynchronous/legacy flash and external SRAM with a
compatible interface.
Each CS bank is configured via its own pair of base and option registers. Each time an internal to external
bus cycle access is requested, the internal address is compared with the base address of each valid base
register (with 17 bits having mask). See
. If a match is found, the attributes defined for this
bank in its BR and OR are used to control the memory access. If a match is found in more than one bank,
the lowest bank matched handles the memory access. For example, bank 0 is selected over bank 1.
bit 28
Reserved.
BSCY
Burst Beats Length in Clocks. This field determines the number of wait states (external bus cycles) inserted in
all burst beats except the first, when the memory controller starts handling the external memory access and thus
is using SCY[0:3] to determine the length of the first beat. These bits are ignored when SETA=1
• Total memory access length for each beat:
• Total cycle length (including the TS cycle):
Note: The number of beats (4, 8, 16) is determined by BL and PS bits in the base register.
00 0-clock cycle wait states (1 clock per data beat)
01 1-clock cycle wait states (2 clocks per data beat)
10 2-clock cycle wait states (3 clocks per data beat)
11 3-clock cycle wait states (4 clocks per data beat)
Table 29-8. EBI_ORn (continued)
Field
Description
(1 + BSCY) External Clock Cycles
(2 + SCY) + [(Number of Beats – 1) x (BSCY + 1)]