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- #Starting watch dog initialization drivers#
- #Starting watch dog initialization software#
- #Starting watch dog initialization code#
- #Starting watch dog initialization Pc#
The PowerPC processor and on-board memory start up in a default configuration set via hardware (CS0 is an output pin that can be configured to be the global chip select for the boot device, HRESET/SRESET, data pins, etc.), and has no dedicated accessible PC register. The Embedded Planet RPXLite Board assumes that on-board ROM (Flash) contains the bootloader monitor/program, called PlanetCore, originally created by Embedded Planet.
#Starting watch dog initialization code#
This additional code may exist in ROM, for a system that is being shipped out of the factory, or loaded from an external host platform (see the callout box with bootcodeExample).įigure 12-7e. After the hardware initialization sequence, executed via initialization device drivers, the remaining system software, if any, is then initialized.
#Starting watch dog initialization drivers#
How initialization is actually done (i.e., the order in which drivers are executed) is typically outlined by the master architecture documentation or in documentation provided by the manufacturers of the board. This first hardware initialization portion of boot-up code is essentially the executing of the initialization device drivers, as discussed in Chapter 8. The same (minimal) general functions are performed by boot code across the various platforms, which are basically initializing the hardware, which includes disabling interrupts, initializing buses, setting the master and slave processors in a specific state, and initializing memory. Some embedded (master) architectures have an internal program counter that is automatically configured with an address in ROM in which the start of the boot-up code (or table) is located, while others are hardware wired to start executing at a specific location in memory.īoot code differs in length and functionality depending on where in the development cycle the board is, as well as the components of the actual platform that need initialization. When power is applied to an embedded board (because of a reset), start-up code, also referred to as boot code, bootloader, bootstrap code, or BIOS (basic input/output system) depending on the architecture, in the system’s ROM is loaded and executed by the master processor.
#Starting watch dog initialization software#
System boot-up means that some type of powerON or reset source, such as an internal/external hard reset (generated by a check-stop error, the software watchdog, a loss of lock by the PLL, debugger, etc.) or an internal/external soft reset (generated by a debugger, application code, etc.), has occurred. With the development tools ready to go and either a reference board or development board connected to the development host, it is time to start up the system and see what happens. The TPS3813xxx devices are characterized for operation over a temperature range of –40☌ to 85☌.Tammy Noergaard, in Embedded Systems Architecture (Second Edition), 2013 12.1.5 System Boot-Up The circuits are available in a 6-pin SOT-23 package. The product spectrum is designed for supply voltages of 2.5 V, 3 V, 3.3 V, and 5 V.
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The supervised processor now needs to trigger the TPS3813xxx within this window not to assert a RESET. The lower limit and thus the window ratio is set by connecting WDR to GND or V DD. The upper limit of the watchdog time-out can be set by either connecting WDT to GND, V DD, or using an external capacitor. All the devices of this family have a fixed-sense threshold voltage (V IT) set by an internal voltage divider.įor safety critical applications the TPS3813xxx family incorporates a so-called window-watchdog with programmable delay and window ratio. When the supply voltage drops below the threshold voltage (V IT), the output becomes active (low) again. The delay time, t d = 25 ms typical, starts after V DD has risen above the threshold voltage (V IT). An internal timer delays the return of the output to the inactive state (high) to ensure proper system reset. Thereafter, the supervisory circuit monitors V DD and keeps RESET active as long as V DD remains below the threshold voltage (V IT).
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The TPS3813xxx family of supervisory circuits provide circuit initialization and timing supervision, primarily for DSPs and processor-based systems.ĭuring power on, RESET is asserted when supply voltage (V DD) becomes higher than 1.1 V. Open-in-new Find other Supervisor & reset ICs