TC1796
System Units (Vol. 1 of 2)
LMB External Bus Unit
User’s Manual 13-3 V2.0, 2007-07
EBU, V2.0
13.2 EBU Interface Signals
The external EBU interface signals are listed in Table 13-1 below.
Note: After reset, all EBU pins (except BFCLKO and BFCLKI) have an internal pull-up
device connected. These pull-up devices can be disconnected together by setting
bit SCU_CON.EPUD.
13.2.1 Data Bus, D[31:0]
The data bus transfers data information. The width of this bus is 32 bits. External devices
with 16 or 32 bits of data width can be connected to the data bus. Burst Mode instruction
fetches can be performed with 16-bit or 32-bit data bus width.
The EBU adjusts the data on the data bus to the width of the external device, according
to the programmed parameters in its control registers. The byte control signals BC[3:0]
specify which parts of the data bus carry valid data.
Table 13-1 EBU Interface Signals
Signal/Pin Type Function
D[31:0] O Data bus lines 0-31
A[23:0] O Address bus lines 0-23
CS[3:0] O Chip select 0-3
CSCOMB O Combined chip select for global select / emulator memory
region select / emulator overlay select
BFCLKO O Burst Mode Flash clock output
BFCLKI I Burst Mode Flash clock input
RD O Read control line
RD/WR O Write control line
ADV O Address valid output
BC[3:0] O Byte control lines 0-3
MR/W O Motorola style read/write control line
WAIT I Wait input
BAA O Burst address advance output
HOLD I Hold request input
HLDA O Hold acknowledge output
BREQ O Bus request output
V
DDEBU
– EBU power supply lines (2.3 - 3.3 V)
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