LM3S1621_15 Datasheet, PDF (493/948 Pages) Texas Instruments – Stellaris LM3S1621 Microcontroller

Stellaris^® LM3S1621 Microcontroller
Bit/Field
15:8
7:6
5:4
3
2
Name
MAXWAIT
WRWS
RDWS
reserved
BSEL
Type
R/W
R/W
R/W
RO
R/W
Reset
0xFF
0x0
0x0
0
0
Description
Maximum Wait
This field defines the maximum number of external clocks to wait while
an external FIFO ready signal is holding off a transaction (FFULL and
FEMPTY).
When this field is clear, the transaction can be held off forever without
a system interrupt.
Note:
When the MODE field is configured to be 0x3 and the BLKEN
bit is set in the EPICFG register, enabling HB16 mode, this
field defaults to 0xFF.
Write Wait States
This field adds wait states to the data phase (the address phase is not
affected). The effect is to delay the rising edge of WRn (or the falling
edge of WR). Each wait state adds 2 EPI clock cycles to the access
time.
Value Description
0x0 Active WRn is 2 EPI clocks.
0x1 Active WRn is 4 EPI clocks.
0x2 Active WRn is 6 EPI clocks.
0x3 Active WRn is 8 EPI clocks.
This field is used in conjunction with the EPIBAUD register.
Read Wait States
This field adds wait states to the data phase (the address phase is not
affected).
The effect is to delay the rising edge of RDn/Oen (or the falling edge of
RD). Each wait state adds 2 EPI clock cycles to the access time.
Value Description
0x0 Active RDn is 2 EPI clocks.
0x1 Active RDn is 4 EPI clocks.
0x2 Active RDn is 6 EPI clocks.
0x3 Active RDn is 8 EPI clocks.
This field is used in conjunction with the EPIBAUD register
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
Byte Select Configuration
This bit enables byte select operation.
Value Description
0 No Byte Selects
Data is read and written as 16 bits.
1 Enable Byte Selects
Two EPI signals function as byte select signals to allow 8-bit
transfers. See Table 10-6 on page 466 for details on which EPI
signals are used.
July 03, 2014
493
Texas Instruments-Production Data