Infineon Technologies TC1784, User Manual

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TC1784
LMB External Bus Unit
User´s Manual 12-3 V1.1, 2011-05
EBUT13L-A, V1.16
12.3 EBU Interface Signals
The external EBU interface signals are listed in Table 12-1 below.
12.3.1 Address/Data Bus, AD[15:0]
This bus transfers address and data information. The width of this bus is 16 bits. External
devices with 8 or 16 bits of data width can be connected to the data bus.
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[1:0]
specify which parts of the data bus carry valid data.
12.3.2 Address Bus, A[20:16]
The total address bus of the EBU consists of 21 address output lines, giving a directly
addressable range of 4 Mbytes (2
21
, 16 bit words). 16 address lines are multiplexed onto
the comibined address/data bus. The uppermost four address lines, A[20:16] are
available as separate signals. An external device can be selected via one of the chip
select lines. Since there are four chip select lines, four such devices with up to 16 Mbytes
of address range can be used in the external system.
12.3.3 Chip Selects, CS[3:0]
The EBU provides four chip select outputs, CS0, CS1, CS2 and CS3. The address
ranges for which these chip selects are generated are programmed separately for each
chip select line in a very flexible way via the address select registers EBU_ADDRSELx.
More details are described on
Page 12-14 .
Table 12-1 EBU Interface Signals
Signal/Pin Type Function
AD[15:0] O Multiplexed Address/Data bus lines 0-15
A[20:16] O Address bus lines 16-20
CS[3:0] O Chip select 0-3
RD O Read control line
RD/WR O Write control line
ADV O Address valid output
BC[1:0] O Byte control lines 0-1
WAIT I Wait input