TC1796
System Units (Vol. 1 of 2)
LMB External Bus Unit
User’s Manual 13-51 V2.0, 2007-07
EBU, V2.0
13.8.2 Demultiplexed Device Configurations
The EBU supports two different configurations of demultiplexed memory/peripheral
devices: 16-bit demultiplexed mode and 32-bit demultiplexed mode.
The 16-bit demultiplexed mode is selected by:
• EBU_BUSCONx.PORTW = 01
B
• EBU_BUSCONx.AGEN = 000
B
For 16-bit demultiplexed devices, the complete 24-bit address is driven at the EBU pins
for the duration of the complete external bus cycle. The 16-bit data is driven to/read from
the D[15:0] pins during the data phase. D[31:16] are not used.
Figure 13-15 Connection of a 16-bit Demultiplexed Device
The 32-bit demultiplexed mode is selected by:
• EBU_BUSCONx.PORTW = 10
B
• EBU_BUSCONx.AGEN = 000
B
For 32-bit demultiplexed devices, the complete 24-bit address is driven at the EBU pins
for the duration of the complete external bus cycle. The 32-bit data is driven to/read from
the D[31:0] pins during the data phase.
Figure 13-16 Connection of a 32-bit Demultiplexed Device
16-Bit
Memory/
Peripheral
Unit
A[23:0]
D[15:0]
Not
Connected
D[15:0]
D[31:16]
A[23:0]
MCA05726
TC1796
EBU
TC1796
EBU
32-Bit
Memory/
Peripheral
Unit
A[23:0]
D[15:0]
D[15:0]
A[23:0]
MCA05727
D[31:16] D[31:16]
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