Operating Modes
9
-22
DSP56303 User’s Manual
9.3.4
Watchdog Modes
The following watchdog timer modes are provided:
n
Watchdog Pulse
n
Watchdog Toggle
9.3.4.1 Watchdog Pulse (Mode 9)
In Mode 9, the timer generates an external signal at a preset rate. The signal period is equal to
the period of one timer clock. After the counter reaches the value in the TCPR, if the
TCSR[TRM] bit is set, the counter is loaded with the TLR value on the next timer clock and
the count resumes. Therefore TRM = 1 is not useful for watchdog functions. If the
TCSR[TRM] bit is cleared, the counter continues to increment on each subsequent timer
clock. This process repeats until the timer is disabled (that is, TCSR[TE] is cleared). If the
counter overflows, a pulse is output on the
TIO
signal with a pulse width equal to the timer
clock period. If the INV bit is set, the pulse polarity is high (logical 1). If INV is cleared, the
pulse polarity is low (logical 0). The counter reloads when the TLR is written with a new
value while the TCSR[TE] bit is set. In Mode 9, internal logic preserves the
TIO
value and
direction for an additional 2.5 internal clock cycles after the hardware
RESET
signal is
asserted. This convention ensures that a valid
RESET
signal is generated when the
TIO
signal
resets the DSP56303.
Bit Settings
Mode Characteristics
TC3
TC2
TC1
TC0
Mode
Name
Function
TIO
Clock
1
0
0
1
9
Pulse
Watchdog
Output
Internal
Summary of Contents for DSP56303
Page 1: ...DSP56303 User s Manual 24 Bit Digital Signal Processor DSP56303UM AD Revision 1 January 2001 ...
Page 52: ...JTAG OnCE Interface 2 22 DSP56303 User s Manual ...
Page 114: ...General Purpose Input Output GPIO 5 10 DSP56303 User s Manual ...
Page 212: ...GPIO Signals and Registers 8 26 DSP56303 User s Manual ...
Page 268: ...Interrupt Equates A 22 DSP56303 User s Manual ...
Page 306: ...Programming Sheets B 38 DSP56303 User s Manual ...
Page 320: ...Index 14 DSP56303 User s Manual ...