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TC1784
LMB External Bus Unit
User´s Manual
12-30
V1.1, 2011-05
EBUT13L-A, V1.16
12.10
Asynchronous Read/Write Accesses
Asynchronous read/write access of the EBU support the following features:
•
EBU_CLK clock-synchronous signal generation
•
Support for 16-bit and
Performing an LMB access with a data width greater than that of the external device
automatically triggers a sequence of the appropriate number of external accesses to
match the LMB access width.
•
Demultiplexed address/data lines
•
Programmable access parameters
– Internal control of command delay cycles
– External and/or internal control of wait states
– Variable data hold cycles for write operation (to allow flexible hold time adjustment)
– Variable inactive/recovery cycles when:
Switching between different memory regions (CS),
Switching between read and write operations,
After each read cycle,
After each write cycle.
Software driver routines are required in order to support Nand Flash devices using
asynchronous device accesses. A single Nand Flash access sequence is performed by
generating the appropriate sequence of discrete asynchronous device accesses in
software.
The EBU does not provide support 8-bit bus width. When 8-bit SRAM devices are used,
they must be used in pairs to implement a 16-bit wide memory region.
12.10.1
Signal List
The following signals of the EBU are used for asynchronous accesses:
Table 12-15 Asynchronous Mode Signal List
Signal/Pin
Type
Function
AD[15:0]
O
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
BC[1:0]
O
Byte control lines 0-1
WAIT
I
Wait input
Summary of Contents for TC1784
Page 1: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 3: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 950: ...TC1784 Direct Memory Access Controller DMA User s Manual 11 132 V1 1 2011 05 DMA V3 03 ...
Page 1949: ...TC1784 General Purpose Timer Array GPTA v5 User s Manual 21 297 V1 1 2011 05 GPTA v5 V1 14 ...
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