Mcf5282 External Signals - Motorola ColdFire MCF5281 User Manual

MCF5282 External Signals

Table 14-5. Default Signal Functions After System
TS
TIP
CS[6:0]
14.2 MCF5282 External Signals
The bus signals provide the external bus interface to the MCF5282.
14.2.1 External Interface Module (EIM) Signals
These signals are used for doing transactions on the external bus.
14.2.1.1 Address Bus (A[23:0])
The 24 dedicated address signals, A[23:0], define the address of external byte, word,
longword and 16-byte burst accesses. These three-state outputs are the 24 lsbs of the
internal 32-bit address bus. The address lines also serve as the SDRAM addressing,
providing multiplexed row and column address signals.
These pins are configured for GPIO ports F, G and H in single-chip mode. The A[23:21]
pins can also be configured for CS[6:4].
14.2.1.2 Data Bus (D[31:0])
These three-state bidirectional signals provide the general purpose data path between the
MCU and all other devices. Data is sampled by the MCF5282 on the rising CLKOUT edge.
The data bus port width and wait states are initially defined for the external boot chip select,
CS0, by D[19:18] during chip configuration at reset. The port width for each chip select and
SDRAM bank is programmable. The data bus uses a default configuration if none of the
chip selects or SDRAM bank match the address decode. The default configuration is a
32-bit port with external termination and burst-inhibited transfers. The data bus can transfer
byte, word, or longword data widths. All 32 data bus signals are driven during writes,
regardless of port width and operand size.
D[26:24, 21, 19:16] are used during chip configuration as inputs to configure the functions
as described in Chapter 30, "Chip Configuration Module (CCM)."
These pins are configured as GPIO ports A, B, C and D in single-chip mode.
14.2.1.3 Byte Strobes (BS[3:0])
The byte strobes (BS[3:0]) define the byte lane of data on the data bus. During accesses,
14-18
Reset (External Boot Mode) (Continued)
Signal
MCF5282 User's Manual
Reset
High
High
High
I/O
O
O
O
MOTOROLA