Chapter 6: SDRAM Memory Controller
TX7901 User’s Manual (Rev. 6.30T – Nov, 2001)
6-14
3. Store dummy data (32-bit) to a location. The address of this store instruction is saved in
the Mode Register as data. The address is shuffled by address mapping. The
corresponding address bit may vary according to the SDRAM chip and DIMM connection.
SDRAMC uses RA[12:0] of sysAddr as a Mode Register value.
Table 6-4 SDRAM Mode Register Settings
Burst Length
2
Burst Type
Sequential
Write burst mode
Programmed burst length
CAS Latency
2 or 3
6.5.2.5 Force
Refresh
The Force Refresh Command is used to execute a refresh cycle. In this mode, any write to
a DIMM causes the Auto Refresh command to be called. The lower address and data are
ignored because the Auto Refresh command uses a refresh counter internal to the SDRAM
chip. At least eight Auto Refresh commands are required for the power on sequence.
6.5.2.6 Initialization
sequence
Intel’s “PC SDRAM Specification” Rev. 1.7, November 1999 recommends the sequence
described below.
Following the initialization sequence, the device must be ready for full functionality. SDRAM
devices are initialized by the following sequence:
1. At least one NOP cycle will be issued after the 1msec device deselect.
2. A minimum pause of 200
µ
sec will be provided after the NOP.
3. A precharge all command will be issued to the SDRAM.
4. Eight Auto Refresh (CBR) refresh cycles will be provided.
5. A mode register set cycle will be issued to program the SDRAM parameters (e.g., Burst
length, CAS# latency, etc.).
6.5.2.7 Important programming note
Program codes that change any SDRAM/SDRAMC parameters should be located in a
memory device other than SDRAM memory (boot ROM, for example). Otherwise, such
program codes may cause a deadlock.
Summary of Contents for TMPR7901
Page 1: ...TX System RISC TX79 Family TMPR7901 Symmetric 2 way superscalar 64 bit CPU ...
Page 14: ...Handling Precautions ...
Page 15: ......
Page 17: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 41: ...4 Precautions and Usage Considerations 4 2 ...
Page 42: ...TX7901 User s Manual Rev 6 30T November 2001 DOCUMENT NUMBER M 99 00004 07 ...
Page 43: ......
Page 259: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 1 13 Removed ...
Page 260: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 2 ...