6 sdram device-specific parameters, 1 precharge-to-activate interval, Sdram device-specific parameters -38 – Motorola MPC8260 User Manual
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10-38
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part III. The Hardware Interface
Table 10-20 shows SDRAM address multiplexing for A16ÐA31.
10.4.6 SDRAM Device-SpeciÞc Parameters
The software is responsible for setting correct values to some device-speciÞc parameter that
can be extracted from the data sheet. The values are stored in the ORx and P/LSDMR
registers. These parameters include the following:
¥
Precharge to activate interval (P/LSDMR[PRETOACT]). See Section 10.4.6.1,
ÒPrecharge-to-Activate Interval.Ó
¥
Activate to read/write interval (P/LSDMR[ACTTORW]). See Section 10.4.6.2,
ÒActivate to Read/Write Interval.Ó
¥
CAS latency, column address to Þrst data out (P/LSDMR[CL]). See
Section 10.4.6.3, ÒColumn Address to First Data OutÑCAS Latency.Ó
¥
Last data out to precharge (P/LSDMR[LDOTOPRE]). Section 10.4.6.4, ÒLast Data
Out to Precharge.Ó
¥
Write recovery, last data in to precharge (P/LSDMR[WRC]). See Section 10.4.6.5,
ÒLast Data In to PrechargeÑWrite Recovery.Ó
¥
Refresh recovery interval (P/LSDMR[RFRC]). See Section 10.4.6.6, ÒRefresh
Recovery Interval (RFRC).Ó
¥
External address multiplexing present (P/LSDMR[EAMUX]). See Section 10.4.6.7,
ÒExternal Address Multiplexing Signal.Ó
¥
External buffers on the control lines present (P/LSDMR[BUFCMD]). See
Section 10.4.6.8, ÒExternal Address and Command Buffers (BUFCMD).Ó
The following sections describe the SDRAM parameters that are programmed in the P/
LSDMR register.
10.4.6.1 Precharge-to-Activate Interval
This parameter, controlled by P/LSDMR[PRETOACT] deÞnes the earliest timing for
activate or refresh command after a precharge command.
Table 10-20. SDRAM Address Multiplexing (A16ÐA31)
SDAM
External Bus
Address
Pins
A16 A17 A18 A19 A20 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 A31
000
Signal driven
on external
pins when
address
multiplexing
is enabled
A8
A9
A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 A23
001
A7
A8
A9
A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22
010
A6
A7
A8
A9
A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21
011
A5
A6
A7
A8
A9
A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20
100
Ñ
A5
A6
A7
A8
A9
A10 A11 A12 A13 A14 A15 A16 A17 A18 A19
101
С
С
A5
A6
A7
A8
A9
A10 A11 A12 A13 A14 A15 A16 A17 A18