AS4C256M16D3
- MPR Functional Description
•One bit wide logical interface via all DQ pins during READ operation.
•Register Read on x16:
•DQL[0] and DQU[0] drive information from MPR.
•DQL[7:1] and DQU[7:1] either drive the same information as DQL [0], or they drive 0b.
•Addressing during for Multi Purpose Register reads for all MPR agents:
•BA [2:0]: don’t care
•A[1:0]: A[1:0] must be equal to ‘00’b. Data read burst order in nibble is fixed
•A[2]: For BL=8, A[2] must be equal to 0b, burst order is fixed to [0,1,2,3,4,5,6,7], *) For Burst Chop 4 cases,
the burst order is switched on nibble base A [2]=0b, Burst order: 0,1,2,3 *) A[2]=1b, Burst order: 4,5,6,7 *)
•A[9:3]: don’t care
•A10/AP: don’t care
•A12/BC: Selects burst chop mode on-the-fly, if enabled within MR0.
•A11, A13, ... (if available): don’t care
•Regular interface functionality during register reads:
•Support two Burst Ordering which are switched with A2 and A[1:0]=00b.
•Support of read burst chop (MRS and on-the-fly via A12/BC)
•All other address bits (remaining column address bits including A10, all bank address bits) will be ignored by
the DDR3 SDRAM.
•Regular read latencies and AC timings apply.
•DLL must be locked prior to MPR Reads.
NOTE: *) Burst order bit 0 is assigned to LSB and burst order bit 7 is assigned to MSB of the selected MPR agent.
Table 19. MPR MR3 Register Definition
MR3
A[2]
MR3
A[1:0]
Read Address
A[2:0]
Function
Burst Length
Burst Order and Data Pattern
BL8
000b
Burst order 0, 1, 2, 3, 4, 5, 6, 7
Pre-defined Data Pattern
[0, 1, 0, 1, 0, 1, 0, 1]
Read Predefined
Pattern for
System
BC4
BC4
000b
100b
Burst order 0, 1, 2, 3
Pre-defined Data Pattern
[0, 1, 0, 1]
Burst order 4, 5, 6, 7
Pre-defined Data Pattern
[0, 1, 0, 1]
1b
00b
Calibration
BL8
BC4
BC4
BL8
BC4
BC4
BL8
BC4
BC4
000b
000b
100b
000b
000b
100b
000b
000b
100b
Burst order 0, 1, 2, 3, 4, 5, 6, 7
Burst order 0, 1, 2, 3
Burst order 4, 5, 6, 7
Burst order 0, 1, 2, 3, 4, 5, 6, 7
Burst order 0, 1, 2, 3
Burst order 4, 5, 6, 7
Burst order 0, 1, 2, 3, 4, 5, 6, 7
Burst order 0, 1, 2, 3
Burst order 4, 5, 6, 7
1b
1b
1b
01b
10b
11b
RFU
RFU
RFU
No Operation (NOP) Command
The No operation (NOP) command is used to instruct the selected DDR3 SDRAM to perform a NOP (CS# low
and RAS#, CAS# and WE# high). This prevents unwanted commands from being registered during idle or wait
states. Operations already in progress are not affected.
Deselect Command
The Deselect function (CS# HIGH) prevents new commands from being executed by the DDR3 SDRAM. The
DDR3 SDRAM is effectively deselected. Operations already in progress are not affected.
Confidential
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Rev. 3.0
Aug. /2014