

                  Changes or Special Notes About Colt Commands
                                                               2015/04/09

        The Colt Audiometer is largely compatible with the FA10 
        audiometer FIPP interface. However there are some exceptions.

        The major exception is that the Colt Real-Time register group has 
        more registers in it than the FA10/12 audiomters. 
        The Real-Time registers are the register group that is used by 
        the 0x1000 command group. 

        On the FA10/12, there are 14 registers in the Real-Time group. 
        On the Colt the number depends on the Software version. Prior to 
        the base firmware version 0.24.9 the number of registers were 
        less than 32. Starting with the Colt base firmware version 0.24.9 
        the Real-Time register group consists of 32 registers. The 
        earlier versions of the Colt base software were development 
        versions and are not supported. If you have one of the early 
        versions, you should update the base firmware. 

        The file ColtFipp.txt describes the available Colt audiometer 
        Fipp commands. 

        If you are writing a program to interact with the Colt audiometer 
        via the FIPP programming interface, there are some operational 
        issues that should be taken note of with the Colt audiometer and 
        how they interact with the computer controlled operation. 

        General Operation of the Fipp Interface

        An important thing to remember is that with the Colt, you must 
        continuously send FIPP commands to the Colt during Audiometric 
        testing. If the Colt does not see a FIPP command within a period 
        of 250 milliseconds, it will go into fail-safe mode. 
        This is a safety issue. It prevents the possibility of a 
        communication failure leaving the Colt in an unsafe condition.

        Normally if the Tablet software is running and connected to the 
        base unit, it will provide the required communication to keep the 
        base unit out of fail-safe mode. If you are not using the 
        tablet with the base unit, then you must make sure that the base 
        unit receives a continuous stream of FIPP commands to keep it 
        alive. 

        When the base unit goes into fail-safe mode, the power led on the 
        base unit will periodically flash red (about once per second) to 
        indicate that it has gone into fail-safe.
        During fail safe, the source outputs are turned off. Once a fipp 
        command has been received, the base unit will exit the fail-safe 
        mode. 






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        If the tablet application is no longer running, or communication 
        with the tablet has been lost for more then 30 seconds, the Blue 
        led on the base unit front panel will flash at about a one second 
        rate. It will be on stead if Bluetooth communication has been 
        established. If fipp communication has not been established or is 
        lost, the screen background will be a light brown color. 

        Base Unit Controls

        The Colt base unit may or may not have mechanical controls to 
        allow those who prefer physical controls to have the knobs and 
        buttons. The controls provided are left and Right Stimulus 
        switches, left and right level controls, and a single Frequency 
        control.

        The controls on the base unit are mapped to the controls on the 
        tablet. If a control is changed on the base unit, the control opn 
        the tablet is updated with the change.


        Stimulus Switches

        Pressing a stimulus switch on the base unit is equivalent to 
        pressing the stimulus switch on the tablet. The same effect 
        occurs if you set the stimulus switch pressed bit flag in the 
        PBMISC register.

        On the FA10, the stimulus Switch pressed was a read-only flag 
        because it was a mechanical switch. On the Colt the bit is 
        writable since the tablet button is a virtual switch. 

        The associated stimulus active flag in the PBSTAT register on the 
        FA10/12 was writable, and was the method used to set the stimulus 
        on or off on the FA10/12 audiometers. 

        On the Colt, the Stimulus presentation flag is read-only. It is 
        controlled only by the base unit. It is turned on when the base 
        unit is presenting an active stimulus signal and is off when the 
        stimulus is not being presented. 

        One thing to be careful of when writing a program to control the 
        Colt audiometer is potential race conditions when handling the 
        stimlus switches (or any other control). If you are monitoring 
        the stimulus pressed flag to determine if the stimulus switch on 
        the base unit or tablet was pressed, that may potential conflict 
        with also using the flag to turn on the stimulus via computer 
        FIPP control. There is a potential race condition that can occur. 
        If the reading and writing of the Real-Time registers gets out of 
        sync, the software may get confused about whether the stimulus is 
        on or off. 






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        A simple way to resolve this is to not use the Real-Time 
        registers to update the computer interface while using the 
        computer to control the Colt. That means that the computer will 
        not detect changes of the base unit controls, or the tablet 
        controls. Since there is the potential of the user interferring 
        with the computer control of the Colt, there are bit flags 
        available to disable the tablet and base unit controls when the 
        Colt is being controlled from the computer interface. 
        It is not a requirement to use the flags, but it does greatly 
        simplify the programming since it prevents the problems presented 
        by inherent race-conditions when allowing multiple use operation. 

        The same issue applies to any of the controls on the Colt 
        interface, but the Stimulus buttons create the bigest potential 
        for the problem to occur since they are used the most and tend to 
        be quickly turned on and off which increases the potential for 
        disruption. 


        Test Channel Flags

        The Test channel flags (PBMisc register) are read-only. They are 
        managed by the base unit. The left or right flag is set based on 
        the last stimulus button that was pressed. If both are pressed, 
        the last one that was pressed is defined as the test channel. 


        Stimulus Safety 

        When the level is set to 100HL or higher, the Colt enters in to 
        Stimulus safety mode. In this mode, the stimulus is automatically 
        turned off after 500ms even if the stimulus button is continued 
        to be pressed. Also, the Reverse Stimulus function is disabled 
        (and the tablet button is disabled). You can disable the 500ms 
        timeout by selecting the Disable Stimulus Safety Timeout option 
        in the preferences menu. Use extreme caution if you disable this 
        feature. The 500ms presentation timeout is not active in speech 
        screen.

        Note: The Reverse Stimulus will always be disabled regarless of 
        the setting of the preference menu item. To keep the stimulus 
        presented, you must hold the stimulus button down. 
        For a FIPP command from the computer interface, it is up to the 
        computer to manage the stimulus presentation appropriately.  












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        Interlock Operation

        The Interlock bit flag controls whether one stimulus button 
        controls both channels or only it's own channel. When the flag is 
        on, the base unit will turn the stimulus on for both channels if 
        it sees either stimulus button pressed flag bit on. A computer 
        control program normally should use the Interlock to control both 
        stimulus switches when they need to be simultanious. 
        For tests that require the "test" channel to be identified, the 
        last stimulus button that was pressed is defined as the test 
        channel. This is another reason to make use of the interlock flag 
        as it allows the base unit to identify the test channel. 

        Tracking Operation

        When Tracking is on, this tells the controlling device that it is 
        to track both level control changes together. It is up to the 
        computer to change the levels appropriately. The base unit will 
        make similar level control updates if one of its level controls 
        is changed. Tracking is only handled at the user control level on 
        the device (computer, tablet or base unit) making the change. 
        Example, if the base unit right level control is changed, it will 
        update the left level control level by the same amount of change 
        difference. However if the computer interface fipp command 
        changes the left level, but not the right level, only the left 
        level is changed. The base unit does not make any changes to the 
        level control information supplied by the computer. 

        Output Revese Operation

        The output reverse flag is just a notation flag. It has no effect 
        on the Real-Time registers. It's purpose is to notify the user 
        interface as to whether the graphs and controls should be 
        displayed as left/right or right/left format. The format of the 
        Real-Time registers is not changed. 

        Patient Response Button

        There are two Patient response button flags on the Colt. A Local 
        response flag (read/write) and an external response flag (read-
        only). The externel patient response flag reflects the state of 
        the switch that the patient holds during audiometric tests. If 
        the switch is not being used, the Local patient response can be 
        used to simulate or override the operation of the external 
        switch. The switch flags are kept separate so that it is known 
        whether it was the patient or the operator who initiated the 
        response condition. 









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        Frequency Controls Operation

        The Real-Time registers have separate left and right frequency 
        controls. Normally the tablet only has a singal frequency control 
        which if changed will set the left and right frequency to the 
        setting on the frequency control. If you will be using different 
        frequencies on the left and right channels and the tablet 
        software is active, you should turn on the dual-frequency flag so 
        that the tablet will not try to set both channels to the same 
        frequency if it sees the left channel changing. 

        Note: When in single frequency control mode, the tablet 
        references the left channel frequency as the master frequency 
        register and reflects any changes made to the left frequecy to 
        the right channel. 

        <eof> -med







































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