Rainbow Electronics W90N740 - Manual (Page 44)

W90N740
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SDRAM Power Up Sequence
The default value of the mode register is not defined, therefore the mode register must be written after
power up to operate the SDRAM. W90N740 supports the function of Power Up Sequence, that is, after
system power on the W90N740 SDRAM Controller automatically executes the commands needed for
Power Up Sequence and set the mode register of each bank to default value. The default value is:
— Burst Length = 1
— Burst Type = Sequential (fixed)
— CAS Latency = 2
— Write Burst Length = Burst (fixed)
The value of mode register can be changed after power up sequence by setting the value of
corresponding bank’s configuration register “LENGTH” and “LATENCY” bits and set the MRSET bit
enable to execute the Mode Register Set command.
7.3.2.3 SDRAM Interface
MCLK
MCKE
nSCS[1:0]
nSRAS
nSCAS
nSWE
nSDQM[3:0]
A[24:0]
D[31:0]
A[10:0]
DQ[[31:0]
DQM[3:0]
nWE
nCAS
nRAS
nCS
BS0
BS1
CLK
CKE
W90N740
A13
A14
A[10:0]
nSCS0
SDRAM
64Mb 512Kx4x32
nSDQM[3:0]
Fig 7.3.1 SDRAM Interface