
4/29/2020
Godson 3A2000 / 3B2000 Processor User Manual
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● Always low;
The timing is shown below:
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Godson 3A2000 / 3B2000 Processor User Manual Part 1
Sys_reset
DDR_RESETn
Internal reset
POWER
Software enableDLL lock
Particle RESETn
By the combination of the latter two reset modes, it can be realized directly using the reset signal of the memory controller
STR control. When the entire system is started from the shutdown state, use the method in (2) to use the memory module to reset normally and
start working. When the system recovers from the STR, use the method in (3) to reconfigure the memory module so that
Under the condition of destroying the original state of the memory module, it restarts to work normally.
9.5.3
Leveling
Leveling operation is in DDR3, used to intelligently configure the phase relationship between various signals in the read and write operations of the memory controller
Operation. Usually it includes Write Leveling, Read Leveling and Gate Leveling. In this controller
Among them, only Write Leveling and Gate Leveling are implemented, Read Leveling is not implemented, the software needs to pass
Judging the correctness of reading and writing to achieve the functions completed by Read Leveling. In addition to DQS operating during Leveling
In addition to the phase and GATE phase, you can also calculate the write DQ phase and read DQ phase based on these last confirmed phases.
Configuration method.
9.5.3.1 Write Leveling
(1) Write Leveling is used to configure the phase relationship between writing DQS and clock. Software programming needs to refer to the following
step.
(2) Complete the controller initialization, see the previous section;
(3) Set Dll_wrdqs_x (x = 0… 8) to 0;
(4) Set Lvl_mode (0x180) to 2'b01;
(5) Sampling the Lvl_ready (0x180) register, if it is 1, it means that the Write Leveling request can be started;
(6) Set Lvl_req (0x180) to 1;
(7) Sampling the Lvl_done (0x180) register, if it is 1, it means that a Write Leveling request is completed;
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