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S3C2451X RISC MICROPROCESSOR
MOBILE DRAM INITIALIZATION SEQUENCE
On power-on reset, software must initialize the memory controller and the mobile DRAM connected to the
controller. Refer to the mobile DRAM(SDRAM or mDDR or DDR2) data sheet for the start up procedure, and
example sequences are given below:
MOBILE DRAM(SDRAM OR MOBILE DDR) INITIALIZATION SEQUENCE
1.
Wait 200us to allow DRAM power and clock stabilize.
2.
Setting the Configuration Register0. This is for MRS and EMRS command to DRAM.
3.
Program the configuration register1, and 3 to their normal operation values
4.
Program the INIT[1:0] to '01b'. This automatically issues a PALL(pre-charge all) cammand to the DRAM.
5.
Write '0xff' into the refresh timer register. This provides a refresh cycle every 255-clock cycles.
6.
Wait minimum 2 auto-refresh cycle; DRAM requires minimun 2 auto-refresh cycle.
7.
Program the INIT[1:0] of Control Register1 to '10b'. This automatically issues a MRS command to the DRAM
8.
Program the normal operational value(auto-refresh ducy cycle) into the refresh timer.
9.
Program the INIT[1:0] of Control Register1 to '11b'. This automatically issues a EMRS command to the
Mobile DRAM, It's only needed for Mobile DRAM.
10. Program the INIT[1:0] to '00b'. The controller enters the normal mode.
11. The external DRAM is now ready for normal operation.
DDR2 INITIALIZATION SEQUENCE
1. Setting the BANKCFG & BANKCON1, 2, 3
2. Wait 200us to allow DRAM power and clock stabilize.
3. Wait minimum of 400 ns then issue a PALL(pre-charge all) command.
Program the INIT[1:0] to '01b'. This automatically issues a PALL(pre-charge all) cammand to the DRAM.
4. Issue an EMRS command to EMR(2), provide LOW to BA0, High to BA1.
Program the INIT[1:0] of Control Register1 to '11b' & BANKCON3[31]='1b'
5. Issue an EMRS command to EMR(3), provide High to BA0 and BA1.
Program the INIT[1:0] of Control Register1 to '11b' & BANKCON3[31:30]='11b'
6. Issue an EMRS to enable DLL and RDQS, nDQS, ODT disable.
7. Issue a Mode Register Set command for DLL reset.(To issue DLL Reset command, provide HIGH to A8 and
LOW to BA0-BA1, and A13-A15.) Program the INIT[1:0] to '10b'. & BANKCON3[8]='1b'
MOBILE DRAM CONTROLLER
6-3
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