Ampro Corporation 486E manual Watchdog Timer, Jumper W4, WDT Response

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Product Reference

Watchdog Timer

The purpose of a watchdog timer is to restart the system should some mishap occur. Possible problems include:

!A failure to boot properly

!Application software losing control

!Temporary power supply problems including spikes, surges, or interference

!Failure of an interface device

!Unexpected conditions on the bus

!Other hardware or software malfunctions

The watchdog timer helps assure proper start-up after any interruption.

The Little Board/486e ROM BIOS supports the board’s watchdog timer function in two ways:

!There is an initial watchdog timer setting, specified using SETUP, which determines whether the watchdog timer is used to monitor the system boot, and if so, the length of the timeout. The options are Disable, 30 seconds, 60 seconds, and 90 seconds.

!There is a standard ROM-BIOS function that can be used by application software to start, stop, and retrigger the watchdog timer function.

The initial time-out should be set using SETUP to be long enough to guarantee that the system can boot and pass control to the application. Once the system is booted and the application is running, the application must periodically retrigger the timer so that a watchdog timer time-out does not occur. If the time-out does occur, the system responds in a manner determined by how the watchdog timer jumper, W4, is set. See Figure 2–11.

W4

Selects -IOCHK

Selects RESET

Figure 2–11. Watchdog Timer Response Jumper (W4)

The watchdog timer uses the standard alarm feature of the real-time clock. In a standard AT, the alarm output is connected to IRQ8. On the Little Board/486e CPU you can also jumper the alarm output to I/O Channel Check (-IOCHCK) or RESET with W4. I/O Channel Check is the bus signal that triggers a non-maskable interrupt (NMI). RESET is a hard reset signal, the same as pressing the Reset button. Watchdog timer responses are summarized in Table 2–45.

Table 2–45. Watchdog Timer Setup

Jumper W4

SETUP

WDT Response

W4-1/2 Shorted

Enabled

I/O Channel Check (NMI)

 

 

 

W4-2/3 Shorted

Enabled

Hardware Reset

 

 

 

W4 Open

Enabled

IRQ8 turns off interrupt. System continues unaffected

 

 

 

W4 Open

Disabled

No action

 

 

 

2–59

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Contents Little Board/486e Computer Revision Reason for Change Date Table of Contents Page Technical Specifications Index Technical Support IntroductionThis page left intentionally blank Viii CPU/Motherboard FeaturesChapter General DescriptionVL-Bus Flat Panel/CRT Display Controller Enhanced Embedded-PC BiosIDE Interface Serial PortsEnhanced Parallel Port Floppy InterfaceByte-Wide Socket and Solid State Disk SSD Ethernet LAN InterfaceModular PC/104 Expansion Bus Enhanced ReliabilityHalt Testing Software Little Board Development Platform Overview Interface Connector SummaryConnectors Connector Function Size Key PinConnector and Jumper Locations Jumper Configuration Options Jumper Group Function DefaultSystem I/O Map Address Function DC Power Connector Type Mating ConnectorPin Connection Power Requirements Backup BatteryCooling Requirements Powerfail Monitor System Memory Map DramMemory Address Function Expanded Memory and Extended MemoryAddresses Serial Ports J11, J13RS-232C Serial Ports RS-485 Serial PortIRQ11 IRQ7 Interrupt AssignmentsSerial Port Connectors J11, J13 ROM-BIOS Installation of the Serial PortsName Pin Ports Pin Signal Function In/Out DB25Pin Signal Name Configuring Serial 2 for RS-485 J6, W5, W6Pin RJ11 Signal Standard Wire Color RS-485 Twisted-Pair Cabling Using RJ11 ConnectorsInterconnection Scheme Examples Using the RS-485 InterfaceSerial Console Hex CommandSerial Handshake COM Port TableUsing a Serial Modem Serial Booting and Serial ProgrammingBi-Directional Parallel Port Register Name Address Primary SecondarySelection Address Interrupts ROM-BIOS Installation of Parallel Ports Signal Type Number of Lines Function Output DriveStandard and General Purpose I/O Operation Parallel Port Interrupt Parallel Port Interrupt Enable Register Bit Signal Name In/Out Active J15Or Function High/Low Pin J15 Pin Signal Function In/Out DB25 Name Parallel Port Connector J15Register Bit Definitions Signal Name Full Name DescriptionFloppy Disk Interface Floppy Drive ConsiderationsCapacity Drive Size Tracks Data Rate Floppy Interface Configuration Floppy Interface Connector J14Pin Signal Name Function In/Out IDE Hard Disk Interface IDE Connector J1225. IDE Drive Interface Connector J12 IDE Interface Configuration Solid-State Disk Preparation Master/Slave SettingCompact Flash Solid-State Disk Enabling the DriveConnecting a CRT J5 Name Connector Pins/Type DescriptionFlat Panel/CRT Video Controller Part Description Mating Connector J5 Pin Signal Name DB-15 DB-9W10 +5V Connecting a Flat Panel J3FLM Pin Signal Description NameAdvanced Power Management Power SequencingPgmebios VIDEO=filename Bios Support of Non-Standard PanelsSelecting Vee Polarity LCD Bias Supply OptionJ4 Pin J3 Pin Description Ra = 270 Rb = Vee max Vee min / 1.5 Attaching an External Contrast ControlExample Network Terms Ethernet Network InterfaceQNX Installing an Ethernet Boot PromTwisted Pair Interface J7 Twisted-Pair InstallationsInstalling a Boot Prom Installing a Boot Prom in Byte-Wide Socket S0Using Network Operating Systems NOS Network OS Drivers Controlling the Ethernet LAN Interface DirectlyProgram Name Vendor Function Driver Name 00 40 Manufacturer’s Ethernet IDByte-Wide Socket S0 SSD Device Size Package Generic Type Pins Part NumberROM-BIOS Extensions Addressing the Byte-wide SocketWindow Address Accessing the Byte-Wide Socket Performance IssuesSolid State Disk SSD Drives Device 64KB Segment Address Size Segments Upper Nibble of BH Jumpering the Byte-Wide Socket Byte-Wide Socket SignalsTypical Devices Pins Jumper Diagram W14 Pin Signal Name DescriptionUsing EPROMs Flash Eprom Typical Devices Pins Jumper DiagramFlash Eprom Programming Non-volatile RAM Using SRAMsUtility Connector J16 Exsmi Pin Signal Name FunctionLED Connection Push Button Reset ConnectionExternal Battery Connections PC SpeakerBattery-Backed Clock Watchdog Timer Jumper W4WDT Response AL,61H AL,NOT 08H OUT 61H,AL Page AT Expansion Bus Onboard MiniModule Expansion Using Standard PC and AT Bus CardsBus Termination Bus Expansion GuidelinesExpansion Bus Connector Pinouts PU/PD/S Pin Signal Function In/Out Current47. AT Expansion Bus Connector, B1-B32 P1 48. AT Expansion Bus Connector, C0-C19 P2 PU/PD/S Interrupt Function Interrupt and DMA Channel UsageChannel Function Serial Parallel FloppyEthernet Video Setup Overview Menu Name Functions Standard CMOS/EEPROM Setup Setup Page 1-Standard CMOS/EEPROM SetupIDE Hard Disk Drives Drive Parameter SetupDate and Time Floppy DrivesPage System Post Error HaltVideo Dram MemoryExtended Bios Setup Page 2-Options/Peripheral ConfigurationSelection Address Interrupt Serial PortParallel Port Port AddressSelection Address Floppy Interface EnableIDE Interface Enable Hot Key Setup EnableBlank Post Test Video StateLocal Bus Video Display Byte-Wide Socket ConfigurationSerial Boot Loader Enable Watchdog Timer ConfigurationFlat Panel Display Type Installing a Modified Bios to Support a New PanelExtended Serial Console Configuration Setup Page 3-Serial Console ConfigurationPage Switch Function Creating Configuration Files with SETUP.COMDIR LPT1 Operation with DOSUtility Software Overview Embedded-PC System Enhancements Little Board/486e CPU SpecificationsOnboard Peripherals CRT Support for Standard Video Modes Vesa Font Pixels Clock Horiz Vert Mem Mode MHz KHz Support Software Mechanical and Environmental Specifications Mechanical Dimensions Technical Specifications Page Index Page POST, Setup Little Board/486e Technical Manual Index-4