Bluetooth BLE MIDI chip IC solution

1. Introduction to BLE MIDI

1.1 In 2014, Apple designed a Bluetooth low energy (BLE) The MIDI protocol was then adopted by MMA members as an industry standard in June 2015. Hence the BLE MIDI protocol. Simply put, it supports the MIDI protocol of BLE.

1.2 The software principle is to parse the BLE MIDI data transmitted from Bluetooth into traditional standard MIDI data, and then output it through the serial port. In the same way, the midi data from the serial port can also be encoded as BLE MIDI data and sent. to mobile.

Classification of Bluetooth MIDI transmission methods

1.3 Signal transmission diagram

1.4 Comparison between BLE MIDI and traditional methods

Type description review

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1. Wired transmission is to connect instruments and speakers through a coaxial audio cable. It is very troublesome. When there are multiple instruments, the site layout is ugly, but the sound quality transmission loss is small, and it supports multiple instruments to be connected to one speaker at the same time. , generally less used

2. 2.4G transmission uses a pair of 2.4G modules to transmit audio to speakers through wireless reception and transmission. The price is expensive. A pair of modules costs about 30 yuan, and the transmission loss is relatively small. , supports multiple musical instruments to be transmitted to one speaker at the same time, generally rarely used

3. Bluetooth transmitting and transmitting The instrument is in Bluetooth transmitting mode on one side, and transmits with the Bluetooth speaker through Bluetooth technology (the Bluetooth speaker works in receiving mode) The price is cheap, one chip is less than 5 yuan, and the transmission loss is acceptable. There is no problem when used in general products. Currently, it can only support one-to-one matching use, which is used frequently

[if !supportLists] 4. [endif] Bluetooth MIDI

The chip KT2025

transmits the audio of the musical instrument to the mobile phone through Bluetooth BLE transparent transmission, and the mobile phone then transmits the data to the Bluetooth speaker via Bluetooth. At present, only the iPhone supports the MIDI protocol. The price is cheap, and a chip is less than 5 yuan. It uses data transmission, and the loss is relatively small. The main factor that affects the sound quality is the sampling type of the chip. It supports multiple musical instruments to be transmitted to the mobile phone at the same time. It will be a mainstream development in the future. Mode

2. Introduction to BLE MIDI chip

2.1. Chip introduction

KT2025 chip is a 4-in-1 chip that supports Bluetooth, U disk and TF card playback A single chip, the highlight of the chip is that it supports lossless music playback, as well as simple and clear serial port control functions, and supports BLE transparent transmission, BLE MIDI, and SPP transparent transmission functions. Greatly reduces the difficulty of developing embedded Bluetooth in other products.

2.2 Chip Parameters

Name Parameters

MP3 file format 1. Supports all bit rates 11172-3 and ISO13813-3 layer3 audio decoding

2. Sampling rate support (KHZ): 8/11.025/12/16/22.05/24/32/44.1/48

3. Supports Normal, Jazz, Classic, Pop, Rock and other sound effects

4. Support 24-bit DAC

USB interface 2.0 standard

UART interface standard serial port, TTL level, baud rate can be set, level required to connect to PC Conversion [such as: CH340G--USB to TTL]

Input voltage 3.3V-5V [7805 is best with a diode in series]

Rated current 20MA [static]

Low power consumption current lt; 200uA

Chip DAC driver main chip DAC can only drive headphones

Operating temperature [-40 degrees] -- [80 degrees]

Humidity 5 ~ 95

Chip model KT2025 SSOP24

2.3? Chip characteristics

1. The chip uses SSOP24 narrow body package

2. The chip has few peripheral components, only 6 capacitors, 5 105s, 1 2P7, and a 24M crystal oscillator are enough

3. The chip has high integration and powerful functions , supports traditional Bluetooth MP3 function, built-in FM radio function

4. Bluetooth audio chip solution

5. Bluetooth data transmission solution---BLE

6 , Bluetooth data transmission solution, dual-mode BLE and SPP

7. Bluetooth audio dual-mode data

8. Support Bluetooth BLE MIDI

9. Support universal AT Serial port command

2.4 standard schematic diagram 3. Description of professional terms

Function remarks

Public functions refer to functions that are available in all modes, such as Adjust volume, mute, switch modes, reset and other operations

Music, MUSIC, and devices refer to the plug-in TF and U disk playback functions

Bluetooth mode Our Bluetooth here supports both audio and audio , also supports BLE and SPP data transmission

BLE is a standard protocol for Bluetooth communication, and is independent of Bluetooth audio

SPP is also a link of the Bluetooth communication protocol , together with Bluetooth audio

Transparent transmission refers to what the mobile phone sends to Bluetooth, and Bluetooth sends it out through the serial port, and vice versa

The serial port refers to the external transmission of the Bluetooth chip Interface, which is the UART port

The background refers to the fact that when playing music, Bluetooth resources are not released and Bluetooth data communication can still be carried out

[if !supportLists] 4. ?[endif] Chip application scenarios

1. Bluetooth audio products such as: Bluetooth speakers, Bluetooth headsets, car Bluetooth, etc.

2. Bluetooth data transmission products such as: smart door locks, Vehicle-mounted OBD detection, smart cars, printers, medical equipment data collection? BLE MID

3. Bluetooth digital audio products such as: Bluetooth music lights, Bluetooth radio

Remarks: Ultra-low requirements In terms of power consumption, this solution is not suitable

5. Summary

In the future, the use of Bluetooth on musical instruments will be a trend, and we will also be more active in this field. There are advantages.