Mute Sync for Parlé TTM-X, TCM-X, or TCM-1 and EX-USB, EX-UBT, or Forte X
This article illustrates the integration between the EX-USB or EX-UBT and Parlé TTM-X microphone mute buttons when used with an external software codec via a USB connection. This same theory can be applied to the FORTE X USB port which also supports mute synchronization.
Parlé TTM-X configuration
This feature requires Tesira firmware version 3.17 or later. The following options must be configured in the Parlé Mic Initialization.
Define LED Logic Inputs
Set this to Logic Inputs control LEDs. In the default configuration, the TTM-X button ring controls the internal microphone mute, and the LED ring follows the state of the mute. Change this option to decouple the LED ring from the internal mute and allow control through logic. The LED1 and LED2 logic input nodes are used to turn the LED ring on or off. Therefore, a Logic State must be used and set to the ON state to enable the LED ring. The RG1 and RG2 logic inputs are used to switch between red and green states. A NOT gate is required to invert the logic signal in order to set the LED ring to red when the EX-USB is muted and green when unmuted.
Use TTM-X Button as Logic
Check this box to enable additional button press logic outputs on the TTM-X input block. The B1 and B2 output nodes represent the state of the TTM-X button ring. When the button is pressed, this logic output is set high as long as the button is held. When released, it will return to a logic low state. These button presses are combined using a Fan-In OR Pulse block to toggle the state of a Flip Flop.
The Fan-In OR Pulse works similarly to an OR gate, but it always outputs a momentary logic low-to-high signal whenever any of its logic inputs receives a rising edge signal (logic change from low to high). This means an OR gate will continue to output a logic high signal if any of its inputs are receiving a logic high signal, but the Fan-In OR Pulse will always respond to a rising edge on any of its inputs, regardless of what the other inputs are receiving. These differences make the Fan-In OR Pulse a better option than the OR gate for certain applications, such as when receiving logic from button presses, or when sending logic to a Flip Flop block, Preset Button block, or Command String block.
Presets
The mute state of the EX-USB is set to high (muted) on a rising edge of the logic input and set to low (unmuted) on a falling edge. Therefore, a Flip Flop is used to control the mute state. Setting the mute state of the USB output block will change the mute state on the computer that is connected over USB when it is running a supported UC platform.
Note that the mute synchronization feature is not supported on all UC platforms. See Using the Tesira EX-UBT for mute synchronization compatibility with available UC platforms.
In order to synchronize the mute and LED states within Tesira when the mute state is cycled from the soft client, two presets must be used to set the state of the Flip-Flop to match the mute state. We use presets to perform the SET and RESET functions common to Flip-Flops used in digital logic.
In the example file, the Mute preset stores the Flip Flop in an "on" state.
The Unmute preset stores the Flip Flop in an "off" state.
The Mute output logic node (M) on the EX-USB block is used to recall a preset based on the state of the mute using a Preset Button block.
When the mute is activated, the output will cycle from logic low to logic high and trigger the first preset. This will recall the state of the Flip-Flop to match the current state of the mute.
When the mute is deactivated, the output will cycle from logic high to logic low. However, we still need a rising edge to trigger the preset button input. Therefore, we take the mute state output and pass it through a NOT gate to invert the logic. Therefore, when the mute status cycles from high to low, the output of the NOT gate will cycle from low to high and recall the preset.
Logic Loops
Tesira is designed to prevent blocks from being connected in a loop, but for mute synchronization, the first blocks in the signal flow will need their mute state updated when the change in mute state is generated at a later point in that signal. Presets can be used to keep all mute states synchronized, but in some circumstances, this can allow a logic loop to form. If a mute loop forms, each mute state will rapidly alternate between muted and unmuted, causing a variety of issues and making the system audio unusable until the system is power cycled or reprogrammed.
There are a couple of methods to prevent multiple, alternating logic signals from looping indefinitely. One method is to only use presets and not use logic connections between blocks. This method uses multiple Preset Button blocks, with one attached to the mute logic output of each block that can have its mute state directly controlled. In this example, the mute and unmute presets will need to include each block that should have its mute state synchronized.
The other method only uses one Preset Button block, and does have a logic connection from each block to the next in the signal flow, but uses a Logic Delay block to allow trailing logic signals to catch up to the initial logic signal. The Logic Delay block should have an off time of 100 ms, and should be placed immediately before the NOT gate and Preset Button block. The preset will only need to include the first mute state in the signal flow, but can include any block that should have its mute state synchronized. This method adds a 10th of a second of delay to the unmute preset, but this is rarely noticeable. Below is an example of each method.
Multiple Preset Buttons Example: Mute Sync Best Practice with Multiple Preset Buttons.tmf
Logic Delay Example: Mute Sync Best Practice with Logic Delay Block.tmf
