20-10
MCF5272 User’s Manual
External Bus Interface Types
20.6 External Bus Interface Types
The MCF5272 supports three types of external bus interfaces. The interface type is
programmed using CSBRn[EBI]. The EBI codes are summarized in Table 20-6.
20.6.1 Interface for FLASH/SRAM Devices with Byte Strobes
CSBRn[EBI] is 00 for FLASH/SRAM devices and peripherals having 16- or 32-bit data
bus widths. These memory devices have separate pins for independent byte strobes, write
enable, chip select, and output enable. All chip selects support this EBI mode.
The number of wait states required for the external memory or peripheral is programmed
through CSORn[WS]. The external transfer acknowledge signal, TA, is provided to allow
off-chip control of wait states. External control of wait states is enabled when CSORn[WS]
is 0x1F. When TA is used to terminate the bus cycle, the bus cycle will have a minimum of
one wait states. Additional wait states can be added by delaying the assertion of TA.
Longword 00
OP0
OP1
OP2
OP3
01
OP1
X
X
X
10
OP2
OP3
X
X
11
OP3
X
X
X
Line 00
OP0
OP1
OP2
OP3
01
OP1
X
X
X
10
OP2
OP3
X
X
11
OP3
X
X
X
Table 20-6. External Bus Interface Codes for CSBRs
A0
CSBRn[EBI] Applicable Chip Select
Note
16-/32-bit
SRAM/ROM
00
All
For 16/32 bit wide memory devices with byte strobe inputs.
BS[3:0]
are byte read/write enables in this mode.
CSBR0[EBI] = 00 at reset.
SDRAM
01
CS7/SDCS only
One physical bank of SDRAM consisting of 16–256 Mbit
devices. The CS7/SDCS CSORn[WS] must be set to 0x1F.
Reserved
10
—
—
8-bit
SRAM/ROM
11
All
SRAM/ROM timing for 8 bit wide memory devices without
byte strobe inputs.
BS[3:0]
function as byte write enables in
this mode.
Table 20-5. Internal to External Data Bus Multiplexer–Write Cycle (Continued)
Transfer Size
A[1:0]
External Data Bus Connection
D[31:24]
D[23:16]
D[15:8]
D[7:0]
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 ...