9-16
MCF5272 User’s Manual
SDRAM Interface
programs the CAS latency of 2 and transfers it into the
SDRAM mode register. After SDRAM initialization is
confirmed, initialization software should change SDTR[CLT]
to CAS latency 1 but should not reinitialize the SDRAM. The
SDRAM controller state machine now runs with CAS latency
1 and SDRAMs run with CAS latency 2, which increases
bandwidth on the SDRAM bank and improves performance.
9.10 SDRAM Interface
Setting CSBRn[EBI] to 0b01 enables chip select CS7 for use with one physical bank of
SDRAM. In this case, CS7 becomes SDCS. The SDRAM memory array may have a 32- or
16-bit data bus width; an 8-bit width is not supported. An array may consist of SDRAM
devices with 8, 16, or 32 bits data bus width. Each SDRAM device can have from 16–256
Mbits.
The interface to the SDRAM devices is glueless. The following control signals are
dedicated to SDRAM: SDCS, SDWE, A10_PRECHG, SDCLK, SDCLKE, RAS0, CAS0,
and SDBA[1:0].
If SDRAM EBI mode is used, CSOR7[WAITST] should be programmed for 0x1F to
ensure that the internal bus cycle termination signal is sourced from the SDRAM controller
and not the chip select module.
NOTE:
The SDRAM shares address and data signals with external
memory and peripherals. Due to stringent SDRAM timing
requirements, it is strongly recommended to buffer the address,
byte strobe, and data buses between the MCF5272 and
non-SDRAM memory and peripherals. Never buffer signals to
the SDRAMs. See Appendix C for details on how to buffer
external memory and peripherals in a system using SDRAM.
The controller allows single-beat read/write accesses and the following burst accesses:
•
16-byte cache line read bursts from 32-bit wide SDRAM with access times of
n-1-1-1. The value of n depends on read, write, page miss, page hit, etc. The enable
extended bursts bit in chip select option register 7 (CSOR7[EXTBURST]) must be
cleared, CSBR7[EBI] must be set for SDRAM, and CSBR7[BW] must be set for a
16-byte cache line width.
•
16-byte cache line read bursts from 16-bit wide SDRAM with access times of
n-1-1-1-1-1-1-1. CSOR7[EXTBURST] must be set, CSBR7[EBI] must be set for
SDRAM, and CSBR7[BW] must be set for 16 bits.
Summary of Contents for DigitalDNA ColdFire MCF5272
Page 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Page 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Page 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Page 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Page 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Page 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Page 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Page 338: ...13 44 MCF5272 User s Manual Application Examples ...
Page 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Page 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Page 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Page 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...