External Bus Interface (EBI)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
29-48
Freescale Semiconductor
Preliminary
29.5
Initialization/Application Information
29.5.1
Booting from External Memory (for Factory Test only)
The EBI block does not support booting directly to external memory (i.e. fetching the first instruction after
reset externally). The MCU uses an internal boot assist module, which executes after each reset. The BAM
code performs basic configuration of the EBI block, allowing for external boot if desired. Refer to
Chapter 32, “Boot Assist Module (BAM)
” for information about the boot modes supported by the MCU.
29.5.2
Running with Single Data Rate (SDR) Burst Memories
This includes flash and external SRAM memories with a compatible burst interface. BDIP is required for
some SDR memories only.
shows a block diagram of an MCU connected to a 32-bit SDR
burst memory.
Figure 29-35. MCU Connected to SDR Burst Memory
Refer to
for an example of the timing of a typical burst read operation to an SDR burst
memory. Refer to
for an example of the timing of a typical single write operation to SDR
memory.
29.5.3
Running with Asynchronous Memories
The EBI also supports asychronous memories. In this case, the CLKOUT, TS, and BDIP pins are not used
by the memory and bursting is not supported. However, the EBI still drives these outputs, and always
drives and latches all signals at positive edge CLKOUT (i.e., there is no asynchronous mode for the EBI).
The data timing is controlled by setting the SCY bits in the appropriate option register to the proper number
of wait states to work with the access time of the asynchronous memory, exactly as done for a synchronous
memory.
CLKOUT
CS0
TS
WE0
ADDR[8:29]
DATA[0:31]
BDIP
OE
MCU
CK
CE
ADV
BAA*
WE**
A[0:21]
D[0:31]
OE
SDR Burstable
Flash or SRAM
* May or may not be connected, depending on the memory used.
Flash memories typically use one WE signal as shown, RAMs use 2 or 4 (16-bit or 32-bit).
**
CAL_CS0 ***
*** Not available on all devices, refer to the Signals chapter
4M x 32