Description

The NXP PNX8330 processor Configuration unit supports three timers, one of which will act as a watchdog device. Once the timer is started it will automatically reset the processor unless software resets the timer at regular intervals. The package CYGPKG_DEVS_WATCHDOG_MIPS_PNX8330 provides an eCos driver for this device, complementing the generic package CYGPKG_IO_WATCHDOG. The functionality should be accessed via the standard eCos watchdog functions watchdog_start, watchdog_reset and watchdog_get_resolution.

The hardware, and thus the watchdog driver, only supports reset mode.

Configuration Options

The PNX8330 watchdog driver package should be loaded automatically when selecting a platform containing a PNX8330 processor, and it should never be necessary to load it explicitly into the configuration. The package is inactive unless the generic watchdog support CYGPKG_IO_WATCHDOG is loaded. Depending on the choice of eCos template it may be necessary to load the latter.

The package provides two main configuration options. CYGIMP_WATCHDOG_HARDWARE can be used to disable the use of the hardware watchdog and switch to a software emulation provided by the generic watchdog package instead. This may prove useful during debugging. CYGNUM_DEVS_WATCHDOG_MIPS_PNX8330_MILLISECONDS determines the timeout before the hardware watchdog resets the system. The default setting gives a 10-second timeout. The maximum timeout is determined by the CPU clock frequency, approximately 70 seconds for a 120MHz processor.

Porting

The watchdog device driver does not require any platform-specific support. The only porting effort required is to list CYGPKG_DEVS_WATCHDOG_MIPS_PNX8330 as one of the hardware packages in the ecos.db target entry.