
SDRAM Controller (SDRAMC)
18-24
Freescale Semiconductor
NOTE
A precharge is required after DRAMs also have a maximum bank-open
period. The memory controller does not time the bank-open period because
the refresh interval is always less.
18.5.1.6
Load Mode/Extended Mode Register Command (
LMR
,
LEMR
)
All SDRAM devices contain mode registers that configure the timing and burst mode for the SDRAM.
These commands access the mode registers that physically reside within the SDRAM devices. During the
LMR
or
LEMR
command, SDRAM latches the address and bank buses to load the values into the selected
mode register.
NOTE
The
LMR
and
LEMR
commands are only used during SDRAM initialization.
Use the following steps to write the mode register and extended mode register:
1. Set the SDCR[MODE_EN] bit.
2. Write the SDMR[BA] bits to select the mode register.
3. Write the desired mode register value to the SDMR[ADDR]. Do not overwrite the SDMR[BA]
values. This step can be performed in the same register write in step 2.
4. Set the SDMR[CMD] bit.
5. For DDR, step 2 to 4 should be performed twice. The first is for the extended-mode register, and
the last is for the mode register.
6. Clear the SDCR[MODE_EN] bit.
18.5.1.6.1
Mode Register Definition
shows the mode register definition. This is the SDRAM’s mode register, not the SDRAMC’s
mode/extended mode register (SDMR) defined in
Section 18.4.1, “SDRAM Mode/Extended Mode
.” Refer to device data sheet for detailed description.
BA1
BA0
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
Field
0
0
OP_MODE
CL
BT
BLEN
Figure 18-10. Mode Register
Table 18-13. Mode Register Field Descriptions
Field
Description
BA1–BA0
Bank address. These must be zero to select the mode register.
A11–A7
OP_MODE
Operating mode.
xx000 Standard Operation (SDR only)
00000 Normal Operation (DDR)
00010 Reset DLL (DDR)
Else
Reserved
A6–A4
CL
CAS latency. Delay in clocks from issuing a
READ
to valid data out. Check the SDRAM manufacturer’s spec because
the CL settings supported can vary from memory to memory.
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...