Motorola MCF5281 Boot Device Selection, Output Pad Strength Configuration, Clock Mode Selection

				Functional Description
Table 30-11. Chip Configuration Mode Selection 1
Chip Configuration		CCR Register MODE Field
Mode
	MODE2		MODE1	MODE0
Master mode	D26 driven high		D17 driven high	D16 driven high
Single-chip mode	D26 driven high		D17 driven high	D16 driven low
Reserved	D26 driven high		D17 driven low	D16 driven high
Reserved	D26 driven low		D17 don’t care	D16 don’t care

1Modifying the default configurations is possible only if the external RCON pin is asserted low.

During reset, certain module configurations depend on whether emulation mode is active as determined by the state of the internal emulation signal.

30.6.3 Boot Device Selection

During reset configuration, the CS0 chip select pin is optionally configured to select an external boot device. In this case, the V (valid) bit in the CSMR0 register is ignored, and CS0 is enabled after reset. CS0 is asserted for the initial boot fetch accessed from address 0x0000_0000 for the Stack Pointer and address 0x0000_0004 for the program counter (PC). It is assumed that the reset vector loaded from address 0x0000_0004 causes the CPU to start executing from external memory space decoded by CS0.

30.6.4 Output Pad Strength Configuration

Output pad strength is determined during reset configuration as shown in Table 30-12.Once reset is exited, the output pad strength configuration can be changed by programming the LOAD bit of the chip configuration register.

Table 30-12. Output Pad Driver Strength Selection 1

Optional Pin Function Selection	CCR Register LOAD Bit
Output pads configured for partial strength	D21 driven low
Output pads configured for full strength	D21 driven high

1Modifying the default configurations is possible only if the external RCON pin is asserted low.

30.6.5Clock Mode Selection

The clock mode is selected during reset and reflected in the PLLMODE, PLLSEL, and PLLREF bits of SYNSR. Once reset is exited, the clock mode cannot be changed.

Table 30-13summarizes clock mode selection during reset configuration.

MOTOROLA Chapter 30. Chip Configuration Module (CCM) 30-11