Reserved Modes; Special Cases; Timer Behavior During Wait; Timer Behavior During Stop - Motorola DSP56305 User Manual

Note: In this mode, internal logic preserves the TIO value and direction for an
additional 2.5 internal clock cycles after the DSP56305 hardware reset signal is
asserted. This ensures that a valid reset signal is generated when the TIO
signal is used to reset the DSP56305.
9.4.5

Reserved Modes

Modes 8, 11, 12, 13, 14, and 15 are reserved.
9.4.6

Special Cases

Timer behavior during Wait and Stop processing states are special cases.
9.4.6.1

Timer Behavior during Wait

Timer clocks are active during the execution of the WAIT instruction, and timer activity
is undisturbed. If a timer interrupt is generated, the DSP56305 leaves the Wait state and
services the interrupt.
9.4.6.2

Timer Behavior during Stop

During the execution of the STOP instruction, the timer clocks are disabled, timer
activity is stopped, and the TIO signals are disconnected. Any external changes to the
TIO signals are ignored when the DSP56305 is the Stop state. To ensure correct
operation, the timers should be disabled before the DSP56305 is placed into the Stop
state.
9.4.7

DMA Trigger

Each timer can also be used to trigger DMA transfers. For this to occur, a DMA channel
must be programmed to be triggered by a timer event. The timer issues a DMA trigger
on every compare event in all modes of operation. The DMA channel does not have the
capability to save multiple DMA triggers generated by the timer. To ensure that all DMA
triggers are serviced, the user must provide for the preceding DMA trigger to be
serviced before the next trigger is received by the DMA channel.
MOTOROLA DSP56305 User's Manual
Timer/Event Counter
Timer Modes of Operation
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