256Mb and 512Mb (256Mb/256Mb), P30-65nm
Configuration Register
Configuration Register
Read Configuration Register
The read configuration register (RCR) is a 16-bit read/write register used to select bus
read mode (synchronous or asynchronous) and to configure device synchronous burst
read characteristics. To modify RCR settings, use the CONFIGURE READ CONFIGURA-
TION REGISTER command. RCR contents can be examined using the READ DEVICE
IDENTIFIER command and then reading from offset 0x05. On power-up or exit from re-
set, the RCR defaults to asynchronous mode. RCR bits are described in more detail be-
low.
Note: Reading the configuration register is a nonarray READ operation. When the oper-
ation occurs in asynchronous page mode, only the first data is valid, and all subsequent
data are undefined. When the operation occurs in synchronous burst mode, the same
word of data requested will be output on successive clock edges until the burst length
requirements are satisfied.
Table 17: Read Configuration Register
Bits Name
Settings/Description
15 Read mode (RM)
0 = Synchronous burst mode read
1 = Asynchronous page mode read (default)
14:11 Latency count
(LC[3:0])
0000 = Code 0 (reserved)
0001 = Code 1 (reserved)
0010 = Code 2
0011 = Code 3
0100 = Code 4
0110 = Code 6
0111 = Code 7
1000 = Code 8
1001 = Code 9
1010 = Code 10
1011 = Code11
1100 = Code 12
1101 = Code 13
1110 = Code 14
1111 = Code 15 (default)
0101 = Code 5
10 WAIT polarity (WP)
0 = WAIT signal is active LOW (default)
1 = WAIT signal is active HIGH
9
8
Reserved (R)
Default 0, Nonchangeable
WAIT delay (WD)
0 = WAIT de-asserted with valid data
1 = WAIT de-asserted one data cycle before valid data (default)
7
6
Burst sequence (BS)
Clock edge (CE)
Default 0, Nonchangeable
0 = Falling edge
1 = Rising edge (default)
5:4 Reserved (R)
Burst wrap (BW)
Default 0, Nonchangeable
3
0 = Wrap; Burst accesses wrap within burst length set by BL[2:0]
1 = No Wrap; Burst accesses do not wrap within burst length (default)
2:0 Burst length (BL[2:0]) 001 = 4-word burst
010 = 8-word burst
011 = 16-word burst
111 = Continuous burst (default)
(Other bit settings are reserved)
Read Mode
The read mode (RM) bit selects synchronous burst mode or asynchronous page mode
operation for the device. When the RM bit is set, asynchronous page mode is selected
(default). When RM is cleared, synchronous burst mode is selected.
PDF: 09005aef84566799
p30_65nm_MLC_256Mb-512mb.pdf - Rev. C 12/13 EN
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