Tiburon ROV Data Concentrator
Isolated IO Board
Software Functionality

Andrew Pearce
17 Feb 1995


Hardware Summary
The IBC Isolated I/O Board (ISO_IO - assembly 40xx) provides one 8 bit
wide digital input port, one 8 bit wide digital output port and four
8 bit D to A Output ports (DAC).

The hardware provides one write-only register which controls the state
of the output port, one read-only register which returns the state of
the digital input port, four write-only registers for controlling the
DAC outputs and pseudo-register which controls the state of the
on-board LED. The Isolated I/O board does not generate interrupts.

An IBC Bus reset, at power up or under software control, will switch
off the output switches, set the DAC outputs to 0 volts and switch off
the LED.

Refer to the Design and Programming Notes for more detailed information.


Software Summary
The software library for the ISO_IO board provides functions to switch
On/Off the digital outputs, read the state of the digital input port
and control the DAC output voltage.

A board identification and initialization function is provided to
locate the board, insert an entry in the IBC Card table and initialize
the Isolated I/O board.


Directories and Files
All files for the ISO_IO board software are located in the iso_io
directory. C Source for the library functions is contained in
iso_io.c. Hardware register offsets, various bit definitions, a
definition for the iso_IO_BoardEntry data structure and function
prototypes for the function library are located in the header file 
iso_io.h. An appropriate make file is also provided.


Software Functionality

Initialization
All IBC Microcontroller applications execute an IBC board
identification procedure at power up. For the ISO_IO board this
function is called iso_IO_BoardSearch. The function searches for
Isolated I/O boards at predefined addresses (C0H, C4H, C8H) by calling
the iso_IO_BoardInit function with the address as a parameter.

The iso_IO_BoardInit function checks for the presence of a board by
reading the input port register for the specified board address and
checking for an IBC bus timeout. A NULL iso_IO_BoardEntry pointer is
returned if an IBC bus timeout occurs during the read. If the board
responds then an iso_IO_BoardEntry data structure is allocated and
initialized with appropriate default values. All output channels are
switched OFF, the DAC outputs are set to 0 Volts and the LED is
switched ON.


Library Functions
The iso_IO_ReadPort function returns the 8 bit wide value of the
digital input port for ISO_IO board address specified.

The iso_IO_WritePort function writes a value to the 8 bit wide
digital output port for ISO_IO board address specified. The value is
saved in the board data structure to allow other functions to
manipulate individual port bits. 

The iso_IO_SetPortBit function sets an individual digital output port
bit to the state specified (TRUE or FALSE) by the state parameters.
Positive true logic is used so TRUE sets the bit high (5V).

The iso_IO_WriteDacPort function writes an 8 bit value to the 
DAC output channel for ISO_IO board address specified and so changes the
channel's output voltage.

The iso_IO_ReadPortCmd, iso_IO_WritePortCmd, iso_IO_SetPortBitCmd and
iso_IO_WriteDacCmd provide an interface between serial interface
command set and the ISO_IO board functions described above. The
functions process commands from the serial port by decoding and range
checking the command parameters, checking for the presence of the 
ISO_IO board specified and calling the appropriate ISO_IO board
function. 

All Cmd functions return CMD_OK if the function executes correctly,
CMD_ERROR if an error occurs or EARGUMENT if inappropriate parameters
are supplied. The iso_IO_ReadPortCmd function also returns the value
of the digital input port.