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VxWorks

Hardware Considerations Guide, 6.0

Timestamp Clock

Many of the generic timers in target/src/drv/timer include timestamp

functionality. A timestamp driver provides a high-resolution time measurement

facility, typically used by the WindView product. See the VxWorks Device Driver

Developer’s Guide for more information on the API.

Serial Ports

The Tornado tools currently require that the target have at least one RS-232 serial

port or an Ethernet port, which is needed during the development and debug

phases. The serial device should be configurable to operate at a number of

“standard” baud rates; 9600 is preferred for console output, and higher rates are

preferred if the serial port is used for Tornado communication. Standard

communications parameters are 8 data bits, 1 stop bit, no parity, and no modem

control lines. It is possible to boot VxWorks without a serial interface, and in

production, it is conceivable that embedded systems will not have a serial

interface.

VxWorks supports software flow control; hardware flow control signals are

usually ignored. Therefore, only three lines (transmit, receive, and signal ground)

are required for operation.

The API for SIO type serial drivers has been expanded to include support for

hardware flow control and for changing the operational parameters for each serial

device. The user can alter the hardware options flag for each device in order to

change the number of data bits, data parity, stop bits, and to enable or disable

hardware flow control. The default settings are always to use 8 data bits, 1 stop bit,

no parity, and no hardware flow control. The ioctl code for changing hardware

options is

SIO_HW_OPTS_SET (0x1005). The code SIO_HW_OPTS_GET (0x1006)

can be used to read the current hardware options. See target/h/sioLib.h for the

values assigned to the options flag bits. Not all drivers have been updated to

respond to these new ioctl commands yet.

Additional serial ports may be provided by the hardware and required by the

application, they are not required by VxWorks. If multiple serial ports are present,

you should be able to set their baud rates independently.

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