8-5
Copyright 2008 Cirrus Logic, Inc.
DS732UM7
SDRAM/Flash Controller Interface
CS4953xx Hardware Users Manual
CRUSConfig
Bit 31:9 = 0 = Reserved
Bit 8 = Pin Mapping, where:
0 = Enable Flash and SDRAM Mapping
1 = Enable Flash and SRAM Mapping
Bit 7:0 = 0 = Reserved
0x8100005D
0xHHHHHHHH
Default: 0x00000000
DynamicRefresh
Configure the refresh period
Bit 31:11 = 0 = Reserved
Bit 10:0 = REFRESH, where:
0x0 = refresh disabled.
0x1 = 1x16 = 16 HCLK ticks between refresh cycles
0x8 = 8x16 = 128 HCLK ticks between refresh cycles
0x1 to 0x7FF = REFRESH*16 HCLK ticks between refresh cycles
Example:
Refresh Period = 15.625
μ
S, HCLK = 120Mhz
REFRESH = (15.625
μ
S*120Mhz)/16 = 117 = 0x75
0x81000061
0xHHHHHHHH
Default 0x00000075
DynamictRP
Configure the precharge command period
Bit 31:4 = 0 = Reserved
Bit 3:0 = Trp, where:
0x0 to 0xE = (n + 1) DSP clk cycles.
0xF = 16 DSP clk cycles.
Example:
Trp = 20nS, HCLK = 120Mhz
Trp =20nS*120Mhz - 1 = 1.4 = 0x2
0x81000062
0xHHHHHHHH
Default 0x00000002
DynamictRAS
Configure the active to precharge command period
Bit 31:4 = 0 = Reserved
Bit 3:0 = Tras, where:
0x0 to 0xE = (n + 1) DSP clk cycles.
0xF = 16 DSP clk cycles.
Example:
Tras = 45nS, HCLK = 120Mhz
Tras =45nS*120Mhz - 1 = 3.8 = 0x4
0x81000063
0xHHHHHHHH
Default 0x00000004
DynamictREX
Configure the self refres exit time. Also known as Tsre
Bit 31:4 = 0 = Reserved
Bit 3:0 = Trex, where:
0x0 to 0xE = (n + 1) DSP clk cycles.
0xF = 16 DSP clk cycles.
Example:
Trex = 83 nS, HCLK = 120Mhz
Trex = 83 nS * 120 Mhz - 1 =10-1 = 0x9
0x81000064
0xHHHHHHHH
Default 0x00000009
Table 8-2. SDRAM/Flash Controller Parameters (Continued)
Mnemonic
Hex Message
Содержание CS4953xx
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