External Bus Interface (EBI)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
29-5
Preliminary
Address on data bus multiplexing also supports the 16-bit data bus mode (MCR[DBM]=1) and 16-bit
memories (ORx[PS]=1). The user can select which 16 data signals are used (AD[0:15] or AD[16:31]) by
writing the D16_31 bit in the EBI_MCR. For either setting of D16_31, the 16 least significant bits (LSBs)
of external address (ADDR[16:31]) are driven onto the selected 16 AD pins. If additional address lines are
required to interface to the memory, then non-muxed address pins are required to complete the address
space (ADDR[8:15] are available as non-muxed address pins).
Section 29.4.2.11, “Address Data Multiplexing
,” for more details.
29.1.3.7
Debug Mode
When the MCU is in debug mode, the EBI behavior is unaffected and remains dictated by the mode of the
EBI.
29.1.3.8
Stop Mode
The EBI supports a stop mode mechanism used for MCU power management. When a request is made to
enter stop mode (controlled in SIU_HLT register outside EBI), the EBI block completes any pending bus
transactions and acknowledges the stop request. After the acknowledgement, the system clock input may
be shut off by the clock driver on the MCU. While the clocks are shut off, the EBI is not accessible. While
in stop mode, accesses to the EBI from the internal master will terminate with transfer error (internally, no
external TEA assertion).
29.2
Signal Description
29.2.1
External Signal Description
29.2.1.1
BDIP — Burst Data in Progress
BDIP is asserted to indicate that the EBI is requesting another data beat following the current one.
BDIP is driven by the EBI on all EBI-mastered external burst cycles, but is only sampled by burst mode
memories that have a corresponding pin.
29.2.1.2
ADDR [8:15] — Address Lines 8-15
The ADDR[8:15] signals specify the physical address of the bus transaction.
29.2.1.3
CLKOUT — Clockout
CLKOUT is a general-purpose clock output signal to connect to the clock input of SDR external memories
and in some cases to the input clock of another MCU in multi-master configurations.
29.2.1.4
CS [0:3] — Chip Selects 0-3
CSx is asserted by the master to indicate that this transaction is targeted for a particular memory bank on
the Primary external bus.