It is possible to reduce the duty cycle down to as low as 0.5% at the expense of response time. The response time can be specified via S Registers 508 and 510 for page and inquiry respectively, where the worst case response time can be as high as 2.5 seconds. Then the duty cycle can be varied by changing the value of S Registers 509 and 511 appropriately.

For example, if S Register 508 and 510 are both set to 1000ms and S Register 509 and 511 are both set to 11ms then the duty cycle is reduced to 1%, this means that average current drain at 5.0v will be 2% of 65mA plus the normal idle mode current, that is, it is as low as 2.75mA. However, in this case, it can take up to 1 second to establish a connection.

The connected state current consumption while a master or slave can be considerably reduced by enabling Sniff mode, described in detail in the next section.

5.4 Low Power Modes using Sniff

Bluetooth connections are master/slave in nature. A master sends packets and a slave has to acknowledge that packet in the next timeslot. Timeslots in Bluetooth are 625 microseconds wide. This implies that a master will always know when packets will be sent and received, which further means it is able to optimise power usage by switching on power hungry circuitry only when needed.

A slave on the other hand does NOT have prior knowledge of when a packet will be received and has to assume that a packet will be received from a master on every receive slot. This means that it has to leave it’s receiving circuitry on for most of the receive slot duration. The result of this is high power consumption as illustrated in the power table above, where a slave with no data transmission still consumes around 31mA whereas a master consumes only 6mA.

This problem was identified very early in the evolution of Bluetooth (especially since headsets spend all their time as a slave in a Bluetooth connection) and it was solved by having a mode called Sniff, with appropriate lower layer negotiating protocol.

Sniff mode during connection is basically an agreement between the slave and its master that data packets will only be exchanged for N timeslots every M slots. The slave can then assume that it will never be

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TDK blu2i manual Low Power Modes using Sniff
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blu2i specifications

The TDK Blu2i is an innovative Bluetooth audio device designed to elevate the listening experience for audiophiles and casual listeners alike. This versatile device combines advanced Bluetooth technology with high-quality audio performance to create an outstanding solution for wireless sound.

One of the standout features of the TDK Blu2i is its compatibility with various Bluetooth profiles, allowing it to seamlessly connect with a wide range of devices, including smartphones, tablets, and laptops. Utilizing the latest Bluetooth 5.0 technology, the Blu2i ensures a stable connection, reduced latency, and an extended range, making it ideal for both indoor and outdoor use.

In terms of audio performance, the TDK Blu2i boasts impressive sound quality. The device supports high-resolution audio streaming, delivering superior clarity and detail. Users can enjoy their favorite tracks with deep bass, crisp highs, and an overall balanced sound profile. The built-in digital signal processing (DSP) enhances audio playback, ensuring that every note is rendered with precision.

Another notable characteristic is the TDK Blu2i's long-lasting battery life. With up to 20 hours of playback on a single charge, users can indulge in extended listening sessions without worrying about frequent recharging. The device also features quick charge capability, allowing users to enjoy several hours of playback with just a short charging session.

The design of the TDK Blu2i is both stylish and functional. Its compact and lightweight form factor makes it easy to carry, while its durable construction ensures it can withstand everyday use. The device is equipped with intuitive controls, allowing users to adjust volume, skip tracks, and manage calls effortlessly.

Additionally, the TDK Blu2i supports voice assistant integration, enabling users to access their smart devices hands-free. This feature adds an extra layer of convenience, allowing for seamless multitasking without the need to reach for a phone.

In summary, the TDK Blu2i is a powerful Bluetooth audio device that encapsulates the essence of modern audio technology. With its high-quality sound, extensive battery life, and user-friendly features, it caters to the needs of any audio enthusiast looking for a reliable and high-performing wireless solution.
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