Specifications

Chapter 3 Hardware

36 Reference Manual LittleBoard 800

Serial Console Setup

The serial console feature is implemented by connecting a standard null modem cable or modified serial

cable (or “Hot Cable”) between one of the serial ports, such as Serial 1 (J11A) and the serial terminal, or a

PC with communications software. The BIOS Setup Utility controls the serial console settings on the

LittleBoard 800. Refer to Chapter 4, BIOS Setup for the settings of the serial console option, the serial

terminal, or PC with communications software and the connection procedure.

Hot (Serial) Cable

To convert a standard serial cable to a Hot Cable, specific pins must be shorted together at the Serial port

connector or at the DB9 connector. For example, short the RTS (7) and RI (9) on the respective DB9 port

connector as shown in Figure 3-3.

Figure 3-3. Hot Cable Jumper

Watchdog Timer

The watchdog timer (WDT) restarts the system if a mishap occurs, ensuring proper start-up after the

interruption. Possible problems include failure to boot properly, the application software’s loss of control,

failure of an interface device, unexpected conditions on the bus, or other hardware or software malfunctions.

The WDT (watchdog timer) can be used both during the boot process and during normal system operation.

• During the Boot process – If the operating system fails to boot in the time interval set in the BIOS, the

system will reset.

Enable the WDT in Boot Settings Configuration of BIOS Setup. Set the WDT for a time-out interval in

seconds, between 1 and 255, in one-second increments in the Boot Setting Configuration screen. Ensure

you allow enough time for the boot process to complete and for the OS to boot. The OS or application

must tickle the WDT as soon as it comes up. This can be done by accessing the hardware directly or

through a BIOS call.

• During System Operation – An application can set up the WDT hardware through a BIOS call, or by

accessing the hardware directly. Some ADLINK Board Support Packages provide an API interface to

the WDT. The application must tickle the WDT in the time set when the WDT is initialized or the

system will be reset. You can use a BIOS call to tickle the WDT or access the hardware directly.

The BIOS implements interrupt 15 function 0C3h to manipulate the WDT.

• Watchdog Code examples – ADLINK has provided source code examples on the LittleBoard 800

Support Software DVD illustrating how to control the WDT. The code examples can be easily copied to

your development environment to compile and test the examples, or make any desired changes before

compiling. Refer to the WDT Readme file on the LittleBoard 800 Support Software DVD.

Standard DB9 Serial

Port Connector (Female)

Rear View

LB800Hotcable