SPRS357D August 2006 – June 2020 TMS320F28044
PRODUCTION DATA.
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The watchdog block on the F28044 is similar to the one used on the 240x and 281x 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 6-21 shows the various functional blocks within the watchdog module.
The WDINT signal enables the watchdog to be used as a wakeup from IDLE/STANDBY mode.
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 OSCCLK. The WDINT signal is fed to the LPM block so that it can wake the device from STANDBY (if enabled). See Section 6.7, Low-Power Modes Block, for 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.