20-26
MCF5272 User’s Manual
Reset Operation
The levels of the mode select inputs, QSPI_Dout/WSEL, QSPI_CLK/BUSW1, and
QSPI_CS0/BUSW0, are sampled when RSTI negates and select the port size of CS0 and
the physical data bus width after a master reset occurs. The INTx signals are synchronized
and are registered on the last falling edge of CLKIN where RSTI is asserted.
A master reset causes any bus cycle (including SDRAM refresh cycles) to terminate. In
addition, master reset initializes registers appropriately for a reset exception. During an
external master reset, SCR[RSTSRC] is set to 0b11 to indicate that assertion of RSTI and
DRESETEN caused the previous reset.
20.12.2 Normal Reset
External normal resets should be performed anytime it is important to maintain the data
stored in SDRAM during a reset. An external normal reset is performed when an external
device asserts RSTI while negating DRESETEN.
During an external normal reset, RSTI must be asserted for a minimum of six CLKINs.
Figure 20-22 is a functional timing diagram of external normal reset operation, illustrating
relationships among RSTI, DRESETEN, RSTO, mode selects, and bus signals. RSTI and
DRESETEN are internally synchronized on consecutive falling and rising clocks before
being used and must meet the specified setup and hold times to the falling edge of CLKIN
only if recognition by a specific falling edge is required
.
Figure 20-22. Normal Reset Timing
When the assertion of RSTI is recognized internally, the MCF5272 asserts the reset out pin
(RSTO). RSTO is asserted as long as RSTI is asserted and remains asserted for 32,768
CLKIN cycles after RSTI is negated. For proper normal reset operation, DRESETEN must
be negated as long as RSTI is asserted.
The levels of the mode select inputs, QSPI_Dout/WSEL, QSPI_CLK/BUSW1, and
VDD
RSTI
Mode Select
CLKIN
RSTO
T >= 6
CLK CYCLES
T = 32,768
CLK CYCLES
T >= 22
CLK CYCLES
BUS SIGNALS
DRESETEN
Inputs
(H)
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 ...