Samsung S3C6400X User Manual page 110

DRAM CONTROLLER
SDRAM INITIALIZATION SEQUENCE
On power-on reset, software must initialize the DRAM controller and each of the SDRAM connected to the DRAM
controller. Refer to the SDRAM data sheet for the start up procedure. Example sequences are given below.
DRAM CONTROLLER INITIALIZATION SEQUENCE
Program memc_cmd to '3'b100', which makes DRAM Controller enter 'Config' state.
Write memory timing parameter, chip configuration, and id configuration
Wait 200us to allow SDRAM power and clock to stabilize. However, when CPU starts working, power and
clock would already be stabilized.
Execute memory initialization sequence.
Program memc_cmd to '3'b000', which makes DRAM Controller enter 'Ready' state.
Check memory status field in memc_stat until memory status becomes '2'b01',which means 'Ready'.
SDR/MOBILE SDR SDRAM INITIALIZATION SEQUENCE
Program mem_cmd in direct_cmd to '2'b10', which makes DRAM Controller issue 'NOP' memory
command.
Program mem_cmd in direct_cmd to '2'b00', which makes DRAM Controller issue 'Prechargeall' memory
command.
Program mem_cmd in direct_cmd to '2'b11', which makes DRAM Controller issue 'Autorefresh' memory
command.
Program mem_cmd in direct_cmd to '2'b11', which makes DRAM Controller issue 'Autorefresh' memory
command.
If memory type is mobile SDR SDRAM,
Program mem_cmd to '2'b10' in direct_cmd, which makes DRAM Controller issue 'MRS' memory
o
command
Bank address for EMRS must be set.
o
Program mem_cmd to '2'b10' in direct_cmd, which makes DRAM Controller issue 'MRS' memory
command.
Bank address for MRS must be set.
o
DDR/MOBILE DDR SDRAM INITIALIZATION SEQUENCE
Program mem_cmd in direct_cmd to '2'b10', which makes DRAM Controller issue 'NOP' memory
command.
Program mem_cmd in direct_cmd to '2'b00', which makes DRAM Controller issue 'Prechargeall' memory
command.
Program mem_cmd in direct_cmd to '2'b11', which makes DRAM Controller issue 'Autorefresh' memory
command.
Program mem_cmd in direct_cmd to '2'b11', which makes DRAM Controller issue 'Autorefresh' memory
command.
Program mem_cmd to '2'b10' in direct_cmd, which makes DRAM Controller issue 'MRS' memory
command
Bank address for EMRS must be set.
o
Program mem_cmd to '2'b10' in direct_cmd, which makes DRAM Controller issue 'MRS' memory
command.
Bank address for MRS must be set.
o
Program mem_cmd in direct_cmd to '2'b11', which makes DRAM Controller issue 'Autorefresh' memory
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
5-4
Specifications and information herein are subject to change without notice.
S3C6400X RISC MICROPROCESSOR
registers.