Datasheet

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OSCCLK
WDCR (WDPS[2:0])
WDCLK
WDCNTR[7:0]
WDKEY[7:0]
Good Key
Bad Key
1
0
1
WDCR (WDCHK[2:0])
Bad
WDCHK
Key
WDCR (WDDIS)
Clear Counter
SCSR (WDENINT)
Watchdog
Prescaler
Generate
Output Pulse
(512 OSCCLKs)
8-Bit
Watchdog
Counter
CLR
WDRST
WDINT
Watchdog
55 + AA
Key Detector
XRS
Core-reset
WDRST
(A)
Internal
Pullup
TMS320F2810, TMS320F2811, TMS320F2812
TMS320C2810, TMS320C2811, TMS320C2812
www.ti.com SPRS174T –APRIL 2001–REVISED MAY 2012
3.11 Watchdog Block
The watchdog block on the F281x and C281x is identical to the one used on the 240x devices. The
watchdog module generates an output pulse, 512 oscillator clocks wide (OSCCLK), whenever the 8-bit
watchdog up counter has reached its maximum value. To prevent this, the user disables the counter or the
software must periodically write a 0x55 + 0xAA sequence into the watchdog key register which will reset
the watchdog counter. Figure 3-11 shows the various functional blocks within the watchdog module.
A. The WDRST signal is driven low for 512 OSCCLK cycles.
Figure 3-11. Watchdog Module
The WDINT signal enables the watchdog to be used as a wakeup from IDLE/STANDBY mode timer.
In STANDBY mode, all peripherals are turned off on the device. The only peripheral that remains
functional is the watchdog. The WATCHDOG module will run off the PLL clock or the oscillator clock. The
WDINT signal is fed to the LPM block so that it can wake the device from STANDBY (if enabled). See
Section 3.12, Low-Power Modes Block, for more details.
In IDLE mode, the WDINT signal can generate an interrupt to the CPU, via the PIE, to take the CPU out of
IDLE mode.
In HALT mode, this feature cannot be used because the oscillator (and PLL) are turned off and hence, so
is the WATCHDOG.
Copyright © 2001–2012, Texas Instruments Incorporated Functional Overview 53
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