Technical Newsletter V O L U M E I, I S S U E 2 It s Logical! The first newsletter issue received such a great feedback that it was decided to expand the distribution to an international level. It is great to hear that the content of this newsletter is helpful while specifying Biamp Systems products, programming Open Architecture DSP s or troubleshooting installations. This month s topic is about the use of logic in Audia and Nexia. The Biamp support team gets a lot of inquiries on the topic and this brief technical overview will hopefully help you on how to design with logic in mind. The intention is not to give you an electronic tutorial on logic but rather focus on the basic knowledge required to use logic within an Audia/Nexia design. As for advanced programmers, a couple of tips and tricks are also included in this technical newsletter. Remember that we always look forward to hearing your comments, so please feel free to contact the Newsletter editor (Tony) for suggestions you may have. If there are others within your office who may be interested by the content of this Newsletter, let us know and we will add them to the distribution list. Biamp Technical Support Team M A Y I S S U E Logic, the basics you need to know Binary logic is easy! There are only 2 logic states: High (1) and Low (0). The trick to make full use of logic is to understand logic gates: the basic component in digital electronic. Logic gates are used to create digital circuitry. Each logic gate has a truth table that dictates the output state depending on the input. Going over each logic gate (6 in total in Audia/Nexia) and explaining their respective truth tables would not be of much use for beginners in the field of logic. Instead, it is more important to focus on understanding well the basic logic gates: AND, OR and NOT. Then look in the application note Logic control in Audia and Nexia software for the truth table of each gate whenever required. AND Gate - The output is high when both inputs are high, otherwise the output is low Application Example: 2 toggle switches are connected to logic inputs of a logic box/vcb and shall only trigger a remote preset when Switch 1 AND Switch 2 are closed. Use an AND gate to combine both logic signals. (See example below) OR Gate - The output is high if either or both inputs are high, otherwise the output is low Application Example: 2 toggle switches shall trigger the remote preset if either switch is closed. I.e. Switch 1 OR Switch 2 would trigger the preset. Use an OR gate to combine both logic signals. (See example below) NOT Gate - also referred as Inverter reverses the logic state: Low input becomes High output, High input becomes Low output Application Example: If the switch is closed, recall preset 2, if it s open then recall preset 1. (See Example below) FLIP FLOP - Maintains logic state until a input pulse triggers a change to the opposite state. i.e: low to high transition causes logic output to toggle from its present state to the opposite state. Application Example: A momentary switch connected to a flip-flop will behave like a toggle switch. Every contact closure will change the state of the flip flop to its opposite state. LOGIC BOX/VCB I/O - Logic I/O of a Logic Box/Voltage Control Box are open collectors with internal pull up resistors., I.e. both logic inputs and outputs are normally high. While activating the logic input (contact closure), its input will be seen as Low state (0) inside by the DSP. This may explain why, in the following examples, a NOT gate was used to reverse the state of the logic box/vcb inputs (i.e. contact closure will trigger preset). NOR (NOT - OR): The output is high when both inputs are low, otherwise the output is low. It is the inverse behavior of an OR gate. NAND (NOT - AND)- The output is low when both inputs are high, otherwise the output is high.. It is the inverse behavior of an AND gate. AND gate OR gate NOT gate Flip Flop
PAGE 2 Typical logic applications Let s now move on to applying previously described logic concepts to an Audia/Nexia design. As a quick reminder, the universal connectivity structure of a processing block in Audia/Nexia software will always be: Logic inputs on the top and a logic outputs on the bottom of the block Audio inputs on the left side and audio outputs on the right side of the block The following chart summarizes a few of the typical applications for logic enabled DSP blocks. Please refer to the application note Using Logic Control in Audia and Nexia for more information on each DSP block. Device Logic behavior Typical Applications Logic output indicates the state of the gate Trigger remote presets when a microphone becomes active. Logic High (1): Microphone gate ON Trigger command string to control 3 rd party devices such as video router Logic Low(0): Microphone gate OFF or PTZ camera controller via RS232 Trigger camera position through a logic box Auto Mixer Trigger microphone active indicator on davinci, confidence light at the microphone or a tally light on a custom LED panel Room Combiner Ducker Remote Preset Level Inc/Dec Mute Control Command String Event Scheduler Logic input controls the state of the partition inside the room combiner Logic High(1): Partition is open Logic Low(0): Partition is closed Logic input provides manual override of the ducker Logic High(1): Duck Program audio Low(0): Un-duck Program Audio Logic output indicates state of the ducker Logic input triggers preset recall Transition Low to High(1): Triggers preset Transition High to Low(0): N/A Logic input controls increment and decrement of level, if ramping is enabled: Logic High(1) on + node: Ramps up level Logic High(1) on - node: Ramps down level Note: If ramping is disabled, transition low to high increments/decrements level by single step Logic input controls muting Logic High(1): Mute audio Logic Low(0): Un-mute audio Logic input controls send of command string on the RS232 port Transition Low to High(1): Send command Transition High to Low(0): N/A Logic input controls enable/disable of event scheduling: Logic High (1): Event scheduler disabled Logic Low(0): Event scheduler enabled Logic output normally low changes to logic high for 250ms at schedule event time Control the state of the room combiner with partition sensors or other contact closures connected to a logic box Control the state of partition from davinci with the help of logic states Manual override of the ducking Logic output may be used to trigger other actions. E.g.: for emergency announcement pages, the ducker may trigger mute of all program audio until the user manually overrides the system back to its normal state. Trigger chimes after each announcement Presets may be recalled by external/internal logic trigger Connect Select8 to a remote preset to control recall of preset from the field Volume control from momentary switches custom control panel Control Fade In/Out (See example in attached.dap file) Mute control from a contact closure connected to a logic box Mute control from internal logic trigger (e.g. logic state) Control other 3rd party devices with RS232 (control processors, AV equipment, Lighting controller, blind controllers, etc) Use event scheduler to trigger system ON or OFF Manually override event scheduler with logic input Logic Delay Select8 Volume/Select 8 Logic Input controls start/stop of internal delay timer: Logic High(1): Must be present for specified ON time before logic output goes high Logic Low(0): Must be present for specified OFF time before logic output goes low Logic outputs are controlled by the push of Select8 rotary encoder Prevent multiple triggers due to transients for poor quality momentary switches Trigger logic in sequence. For example, a couple of logic blocks connected in daisy chain could create a power up sequencing system for an equipment rack. Triggers the recall of remote preset Push to talk microphone if logic output is connected to a mute block Connecting a flip flop to a Select8 will hold the state of the selection and keep the LED indicator on for multiple selection.
PAGE 3 davinci and Logic While creating your control panel, remember that logic may also be used within davinci for the following blocks: LED Control: You can tie a logic state to an LED to monitor the state from your davinci control panel Command string: You can tie a command string to a button to control the command string output from davinci Toggle Button: You can tie a logic state to a toggle button to control the state (High or Low). Troubleshooting your logic design If a logic design does not perform as expected, the following simple troubleshooting guidelines may be a good starting point: 1. Debug the logic piece by piece: Make sure that each component of the logic design achieves what it is supposed to do. Using logic states as a trigger and remote presets as an activator is a good way to probe your logic design 2. If it s not right, just reverse the logic: Make use of a NOT gate to reverse the logic signal in your design. 3. Design and confirm functionality first: It is recommended to carefully build complex logic design by making sure each section behaves as expected. Trigger external logic I/O (switch, LED, sensors ) to ensure they are not the cause of your problems. 4. Technical Support Help: If logic is not your strength or the troubleshooting is unsuccessful, contact the technical support team to receive design support. Advanced Logic designs Using an open architecture DSP like Audia/Nexia platforms to function as a control system is possible for some circumstances although it may involve complex logic circuitry design skills. For those of you who would be interested, here are a couple of concepts we would recommend learning. Combinational logic: It refers to the theory of combining logic gates to achieve complex behavior. One of the primary requirements while designing complex logic circuits is to simplify them as much as possible. Boolean algebra is a simple and straight forward tool for that matter. Any designers wishing to build advanced logic circuitry will find Boolean algebra and combinational logic a useful tool. Interfacing with control processor: Understanding the basics of how control processors work is a good design reference. Engineering creativity: In most cases, programmers will have to build complex logic features by combining multiple logic blocks, logic gates or maybe interfacing with 3rd party devices. Engineering creativity is a good skill to develop in this case. Finally, to better illustrate how few designers already implemented advanced logic designs on Audia/Nexia DSP platforms, here is a list of typical applications: Parliamentary voting system Control of projector or other AV system Multi-zone phone paging system Airport paging system with custom control panel at each gate Broadcast tally board Automatic room combining Etc...
PAGE 4 DAP file of the month The.dap file of the month illustrates a couple of logic concepts we mentioned in this technical Newsletter. Although this design is a pure fiction, it summarizes well few of the typical applications: Automixer s logic outputs to control PTZ camera or video switcher Partition sensors automatically control the state of the room combiner Momentary switches control Up and Down volume Event scheduler controls System ON/OFF and 3rd party devices such as blinds, lighting controller Select8 is used to override event scheduler to manually disable automatic system ON and shutdown Logic states and logic delays control Fade IN and Fade OUT of the system Combination of momentary switches and flip flop are used to control muting of Audio When emergency page is made, the ducker is activated and ducks program audio. Manual override of the system (e.g. key operated connected to VCB) is then required to set the system back to its default state. Technical Support Team Announcement A new application note has been published by the Biamp Support Group and is available for download on our website in the Tech Support section (www.biamp.com). Understanding Discovery methods in Audia/Nexia/DaVinci software will give you a complete analysis on how UDP broadcast and TCP discovery methods differ. We recommend all designers who are new to the field of Audia/Nexia software to carefully read the application note. For advanced programmers, useful information about VPN connections and troubleshooting techniques may be of interest to you. Biamp Technical Support Team Technical Support Manager Kiley Henner Email: khenner@biamp.com Chris Flanagan Email: cflanagan@biamp.com Michael Erwin Email: merwin@biamp.com Asia/Pacific region Tony Rouget Email: arouget@biamp.com Phone: +852-9305 1255 Skype ID: tonybiamp Biamp Sales Team Contact Info Regional Sales Managers Contact Biamp Systems by phone (1-800.826.1457 or 503.641.7287) for contact information of the local regional sales manager in charge of your area.
PAGE 5