Write Datapath
R
Controller to Write Datapath Interface
Table 2 lists the signals required from the controller to the write datapath.
Table 2: Controller to Write Datapath Signals
Signal Name | Signal | Signal Description | Notes | |
Width | ||||
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ctrl_WrEn | 1 | Output from the controller to the write | Asserted for two CLKDIV_0 cycles for a burst length | |
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| datapath. | of 4 and three CLKDIV_0 cycles for a burst length of | |
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| Write DQS and DQ generation | 8. | |
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| ||
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| begins when this signal is asserted. | Asserted one CLKDIV_0 cycle earlier than the | |
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| WRITE command for CAS latency values of 4 and | |
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| 5. | |
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| Figure 5 and Figure 6 show the timing relationship | |
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| of this signal with respect to the WRITE command. | |
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| |
ctrl_wr_disable | 1 | Output from the controller to the write | Asserted for one CLKDIV_0 cycle for a burst length | |
|
| datapath. | of 4 and two CLKDIV_0 cycles for a burst length of | |
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| Write DQS and DQ generation ends | 8. | |
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| ||
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| when this signal is deasserted. | Asserted one CLKDIV_0 cycle earlier than the | |
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| WRITE command for CAS latency values of 4 and | |
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| 5. | |
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| Figure 5 and Figure 6 show the timing relationship | |
|
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| of this signal with respect to the WRITE command. | |
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| |
ctrl_Odd_Latency | 1 | Output from controller to write |
| |
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| datapath. |
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| Asserted when the selected CAS |
| |
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| latency is an odd number, e.g., 5. |
| |
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| Required for generation of write DQS |
| |
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| and DQ after the correct write |
| |
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| latency (CAS latency – 1). |
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March 2006 | Memory Interfaces Solution Guide | 59 |