Motorola ColdFire MCF5281, User Manual

Page: 301 / 816

MOTOROLA Chapter 14. Signal Descriptions 14-21
MCF5282 External Signals
port size and burst-capability indication, wait-state generation, and internal/external
termination.
Reset clears all chip select programming; CS0 is the only chip select initialized out of reset.
CS0 is also unique because it can function at reset as a global chip select that allows boot
ROM to be selected at any defined address space. The port size for boot CS0 is set during
chip configuration by the levels on D[19:18] on the rising edge of RSTI, as described in
Chapter 30, “Chip Configuration Module (CCM).” The chip-select implementation is
described in Chapter 12, “Chip Select Module.”
These pins can also be configured as A[23:21] and GPIO PJ[3:0].
14.2.2 SDRAM Controller Signals
These signals are used for SDRAM accesses.
14.2.2.1 SDRAM Row Address Strobe (SRAS)
This output is the SDRAM synchronous row address strobe.
This pin is configured as GPIO PSD5 in single-chip mode.
14.2.2.2 SDRAM Column Address Strobe (SCAS)
This output is the SDRAM synchronous column address strobe.
This pin is configured as GPIO PSD4 in single-chip mode.
14.2.2.3 SDRAM Write Enable (DRAMW)
The DRAM write signal (DRAMW) is asserted to signify that a DRAM write cycle is
underway. A read cycle is indicated by the negation of DRAMW.
This pin is configured as GPIO PSD3 in single-chip mode.
14.2.2.4 SDRAM Bank Selects (SDRAM_CS[1:0])
These signals interface to the chip-select lines of the SDRAMs within a memory block.
Thus, there is one SDRAM_CS line for each memory block (the MCF5282 supports two
SDRAM memory blocks).
These pins is configured as GPIO PSD[2:1] in single-chip mode.
14.2.2.5 SDRAM Clock Enable (SCKE)
This output is the SDRAM clock enable.
This pin is configured as GPIO PSD0 in single-chip mode.