TC1796
System Units (Vol. 1 of 2)
LMB External Bus Unit
User’s Manual
13-53
V2.0, 2007-07
EBU, V2.0
13.8.3
Standard Asynchronous Access Phases
Accesses to asynchronous devices are composed of a subset of the standard access
phases which are detailed in
. The standard access phases for
asynchronous devices are:
•
AP: Address Phase (compulsory - see
•
CD: Command Delay Phase (optional - see
•
CP: Command Phase (compulsory - see
•
DH: Data Hold Phase (optional - see
•
RP: Recovery Phase (optional - see
13.8.4
Programmable Parameters
lists the programmable parameters for asynchronous accesses. These
parameters only apply to asynchronous devices when EBU_BUSCONx.AGEN = 000
B
.
Note that emulation registers “EBU_EMU…” include parameters that control the
emulator chip select region (CSEMU output), while “EBU_BUS…x” registers include
parameters that control the four CS[3:0] chip select regions x. The equivalent registers
contain identical bits and bit fields.
Table 13-17 Asynchronous Access Programmable Parameters
Register
Parameter
(Bit/Bit field)
Function
EBU_BUSAPx
EBU_EMUBAP
ADDRC
Number of cycles in address phase; can be
multiplied by CMULT.
CMDDELAY
Number of programmed command delay cycles;
can be multiplied by CMULT.
WAITRDC
Number of programmed wait states for read
accesses; always multiplied by CMULT.
WAITWRC
Number of programmed wait states for write
accesses; always multiplied by CMULT.
DATAC
Number of Data Hold cycles; always multiplied by
CMULT.