Audio feedback in a Fast Touch interface serves two main purposes.
Audio Feedback in a fast touch system can be provided in three ways:
The Fast Touch IC monitors the capacitive touch pad. Whenever, a button is actuated, the Fast Touch IC communicates with the audio feedback driver IC and chooses the desired sound to play. Upon receiving communication from the Fast Touch IC, the data stored in the sound driver IC is used to produce audio using the exciter or sometimes a separate speaker.
Designing an audio feedback system using an exciter is not a trivial process. We need to understand the noise implications of adding the extra circuitry to your fast touch interface.
We have all the tools necessary to analyze the noise created due to the audio feedback exciter and can adjust the noise algorithms accordingly. However, this extra work on our part during the prototyping stage and the extra components needed to make the interface will add cost to the final design.
Has writing specialized software kept you from using capacitive technology? Have no fear, Fast Touch™ is here!
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An exciter placed underneath the fascia or the overlay converts the whole surface as the diaphragm of the speaker. When the exciter is stimulated, the fascia or the interface vibrates creating an audio feedback. A diagrammatic illustration of the audio feedback using an exciter is shown below:
Instead of turning the fascia into a speaker, we can use a standard 8 Ohm speaker to produce sound.
We designed and built this device in 1 day for a very special cause. Using our rapid prototyping capability, we gave a man suffering with ALS (Lou Gehrig’s Disease) his voice back.  To read the full article please click here!
A diagrammatic illustration of the piezo buzzer feedback method is shown below. The Fast Touch IC monitors the capacitive touch pads. Whenever, a button is actuated, the Fast Touch IC generates a PWM waveform. This waveform is fed to the piezo buzzer to produce an audible sound.
This gives the user the necessary assurance that he has engaged with the keypad.
We generally use .wav files provided by our customers to generate the required sound. However, it is important that the customers who need audio feedback note the following
We require that your .wav files have a sample frequency of 4, 5.3, 6.4, 8, 12.8,16 or 32 kHz.
Also, our audio feedback IC uses one of the following Compression Algorithms to slightly reduce the file size further and store it inside the IC.
If we are able to compress a .wav file using 8KHz sample frequency and 4bit ADPCM, then we can usually get around 30 seconds of audio out of our audio driver IC. This is usually 100-105KB of data after compression.
*There might be some loss due to compression, but we can choose the compression technique that gives the best effect, while accommodating your sounds in the IC's flash memory.
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