Interrupt Routing and Generation

3 Functional Description

Watchdog Timers

The Harrier ASIC contains two Watchdog timers, WDT0 and WDT1. Each timer is functionally equivalent but independent. These timers continuously decrement until they reach a count of 0 or are reloaded by software. The time-out period is programmable from 1 microsecond up to 32 minutes. If the timer count reaches 0, a timer output signal is asserted. The output of Watchdog Timer 0 is routed to an MPIC interrupt. The output of Watchdog Timer 1 is connected to the Harrier AUXRST, which will generate RESETOUT_L.

Following a Harrier device reset, WDT0 is enabled with a default time-out of 8 seconds and WDT 1is enabled with a default time-out of 16 seconds. Each timer must be disabled or reloaded by software to prevent a time-out. Software may reload a new timer value or force the timer to reload a previously loaded value. To disable or load/reload a timer requires a two step process.

External interrupts routed to the Harrier MPIC include the four PCI interrupts INTA#-INTD#, four host board interrupts from PMC connector P14, and the output from the watchdog timers. The PrPMC800/800ET has the ability to generate any one of the PCI interrupts INTA#-INTD# by using the Harrier Generic Outbound Doorbell register or the I2O controller. The desired PCI interrupt is selected by programming the PCI Interrupt Mapping bits in the Harrier Bridge PCI Control and Status register.

Asynchronous Serial Port

The PrPMC800/800ET module provides a two-wire asynchronous serial interface (TXD and RXD) for use as a serial debug port. UART0 in the Harrier ASIC provides the 16550 compatible UART controller. The UART0 port SIN0 and SOUT0 signals are wired to an external RS-232 transceiver which interfaces to the 2mm debug header and the P14 connector. An onboard 1.8432 MHz oscillator provides the baud rate clock for the UART.

Clock Generator

The PrPMC800/800ET module clock generator uses a Z9972 PLL clock driver to provide the clocks for the processor, the Harrier ASIC and the SDRAMs. All clocks are referenced to the PCI clock input on PMC connector P11. The PrPMC800/800ET supports the PPC-to-PCI clock ratios listed in the following table. Onboard logic uses the state of the PMC M66EN pin to determine whether the maximum PCI clock frequency will be 33 MHz or 66 MHz.

Table 3-3. PPC to PCI Clock Ratios

M66EN Pin	PPC Clock	PCI Clock	Ratio	Harrier PCI
	Frequency	Frequency	(PPC:PCI)	Clock Divisor
	(MHz)	(MHz)		(N)

Low	100	33.33	3:1	12

High	100	66.67	3:2	6

22PrPMC800/800ET Processor PMC Module Installation and Use (PrPMC800A/IH5)

PRPMC800A/IH5, PrPMC800/800ET Processor PMC Module specifications

The Motorola PrPMC800/800ET Processor PMC Module, specifically the PRPMC800A/IH5 variant, represents a significant advancement in embedded processing technology. Often utilized in telecommunications, aerospace, and defense applications, this PMC module is designed to provide robust performance in demanding environments, making it suitable for high-speed data processing and communication tasks.

At the core of the PrPMC800 module is the PowerPC 750 architecture, known for its efficiency and power management capabilities. This 32-bit RISC processor is clocked at speeds reaching up to 800 MHz, allowing it to handle complex computations and multitasking scenarios effectively. The processor architecture supports a variety of software environments, including real-time operating systems and VxWorks, which enhances its adaptability across diverse applications.

One of the standout features of the PRPMC800A/IH5 module is its memory capacity. The module supports up to 1 GB of SDRAM, offering ample space for processing large datasets and executing multiple applications simultaneously. Furthermore, the integrated PCI bus facilitates high-speed connectivity with other modules and components in the system, ensuring rapid data transfer rates essential for real-time processing tasks.

An important characteristic of the PrPMC800 module is its thermal and environmental resilience. Designed with military-grade standards, it operates reliably in extreme conditions, including high temperatures and vibrations. This makes it particularly suitable for rugged applications where standard commercial-grade processors may fail.

The module also incorporates advanced I/O capabilities, featuring dual Gigabit Ethernet ports which enhance networking performance. Additional serial ports and interrupt handling further improve the module's versatility, allowing it to interface seamlessly with various peripheral devices and systems.

In summary, the Motorola PrPMC800/800ET Processor PMC Module, represented by the PRPMC800A/IH5 model, is an exemplary solution for applications requiring high performance, reliability, and adaptability. With its powerful PowerPC architecture, generous memory capacity, robust I/O capabilities, and proven ruggedness, this processor module stands out as a preferred choice for engineers and developers working in critical industries.

Watchdog Timers