9-2
MCF5272 User’s Manual
SDRAM Controller Signals
bank selects are dedicated SDRAM signals.
Figure 9-1 shows the SDRAM controller signal configuration.
Figure 9-1. SDRAM Controller Signals
Table 9-1 describes SDRAM controller signals.
Table 9-1. SDRAM Controller Signal Descriptions
Signal
Description
A10_PRECHG
A10 precharge strobe. A precharge cycle occurs only after a page miss. During precharge, the
SDRAM writes the designated on-chip RAM page buffer back into the SDRAM array.
Precharge latency is set in SDTR[RP]. The reset value is 2 cycles, RP = 01.
BS[3:0]
For SDRAM devices, these outputs should be connected to individual DQM signals. During
SDRAM accesses, these signals indicate a byte transfer between SDRAM and the MCF5272
when asserted. Note that most SDRAMs associate DQM3 with the MSB, in which case BS3
should be connected to the SDRAM's DQM3 input, and so forth.
CAS0
SDRAM column address strobe output
DRESETEN
DRESETEN is asserted to indicate that the SDRAM controller is to be reset whenever RSTI
asserts. If DRESETEN is negated, RSTI does not affect the SDRAM controller, which
continues to refresh external memory. This is useful for debug situations where a reset of the
device is required without losing data located in SDRAM. DRESETEN is normally tied high or
low depending on system requirements. It should never be tied to RSTI or RSTO.
RAS0
SDRAM row address strobe output
SDA[13:0]/
A[22:0]
Fourteen address signals are multiplexed to form SDRAM_ADR[13:0], which are used for
connecting to SDRAM devices as large as 256 Mbits. SDRAM can be configured for 16- or
32-bit wide interface to the MCF5272 data bus. For an SDRAM array with a 32-bit data bus,
SDRAM address signals are multiplexed starting with A2. For a 16-bit data bus, address
signals are multiplexed starting with A1.
SDRAM Controller
1
1
1
1
4
2
1
1
SDRAMCS/CS7
RAS0
CAS0
SDWE
BS[3:0]
SDBA[1:0]
SDCLKE
SDCLK
A10_PRECHG
A[22:15]
D[31:0]
8
32
Address Multiplexer
Dynamic Bus Sizer
Internal 32-Bit Address Bus
1
A[14:13/SDA[12:11]
2
A[11:2]/SDA[9:0]
10
Содержание DigitalDNA ColdFire MCF5272
Страница 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Страница 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Страница 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Страница 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Страница 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Страница 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Страница 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Страница 338: ...13 44 MCF5272 User s Manual Application Examples ...
Страница 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Страница 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Страница 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Страница 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...
Страница 548: ...INDEX Index 12 MCF5272 User s Manual ...