Introduction to the Design Scheme of Intelligent Electronic Lock Voice Interaction System Based on KT148A Voice Chip

I. Scheme Background and Requirements

In the field of smart home security, intelligent electronic locks have evolved from simple "unlocking tools" to "human-computer interaction terminals". Users have increasingly high requirements for the timeliness, scenario adaptability, and system stability of voice feedback. As a cost-effective 32-bit DSP voice chip, KT148A, with its low power consumption, small package, reprogrammability, and flexible control methods, can perfectly meet the voice interaction needs of intelligent electronic locks. It provides users with clear operation guidance and status prompts while helping manufacturers reduce development costs.

Core Design Requirements

• Scenario-based voice feedback: Covering 10+ core scenarios such as successful unlocking, wrong password, low battery, and anti-pry alarm, realizing "prompt upon operation";

• Compatibility with multiple control methods: Supporting one-wire serial port, button trigger, and MCU command control to adapt to mainstream hardware architectures of electronic locks;

• Low power consumption and long battery life: Adapting to battery-powered scenarios, with standby power consumption below 30μA to ensure a battery life of more than 12 months;

• Flexible voice update: Supporting users to update voice content (such as brand-customized prompts and multi-language switching) through serial ports later without returning to the factory;

• Compact hardware design: SOP8 small package adapts to the limited space inside the electronic lock without requiring additional power amplifier circuits.

II. Hardware System Design

Core Configuration of Voice Module

1. Chip Selection: The KT148A in SOP8 package, with an operating voltage of 2.0V-5.5V, can directly share the 3.3V power supply with the main control MCU of the electronic lock without an additional power management chip;

2. Storage Configuration: Built-in 420KByte storage space, which can store about 420 seconds of voice (calculated at 8KHz sampling rate), enough to accommodate more than 20 scene prompts (such as "Please enter password" and "Fingerprint verification failed"), without external storage;

3. Audio Output: Built-in 16-bit PWM output, which can directly drive an 8Ω/0.5W speaker without an external power amplifier, simplifying the circuit design; a 105 filter capacitor (refer to the reference circuit in Section 2.4 of the manual) can be used to optimize sound quality and reduce noise.

Implementation of Voice Interaction Function

Adaptation to Multiple Control Methods

• One-Wire Serial Control: Realize command transmission through a single IO line (such as sending 0x01 to trigger "Unlocking successful"), saving IO resources of the main control MCU of the electronic lock; the communication timing strictly follows the "6ms initial low level + 8-bit data" rule (Section 3.1 of the manual) to ensure stable command transmission;

• Button Trigger: Use the PB0 pin (KEY function) to design physical buttons, supporting short press to trigger "volume adjustment" and long press to trigger "voice mode switching" (such as switching between Chinese and English prompts);

• MCU Linkage Control: The main control obtains the playback status through detecting the PB9 pin (BUSY signal) of KT148A (low level during playback, high level when idle), and synchronously controls the lock body motor and LED indicator (for example, when playing "Unlocking in progress", the motor synchronously performs the unlocking action).

Power Supply and Power Consumption Optimization

• Wide Voltage Adaptation: When powered by a battery (3.7V lithium battery), it is directly connected to the VBAT pin (Pin8) without an additional voltage stabilizing circuit; if a 2.0V-3.5V low-voltage power supply is used, VBAT and VDDIO (Pin7) must be shorted (Section 2.1 of the manual);

• Low Power Consumption Strategy: Automatically enter standby mode (power consumption <25μA) in non-working periods, and enter ultra-low voltage mode (1.7μA, triggered by F0 command) after 5 seconds of inactivity, greatly extending battery life.

III. Software Function Implementation

1. Voice Content Management and Scenario Adaptation

Classification Design of Voice Library

• Operation guidance: "Please enter password", "Please place your fingerprint", "Verification successful, unlocking in progress";

• Status prompt: "Low battery, please replace", "Wrong password, 2 attempts remaining", "Pry-proof alarm, please note";

• Extended function: "Mute mode enabled", "Temporary password activated".

Playback Mode Configuration

• Insertion priority: Emergency scenarios (such as anti-pry alarm) can interrupt the current playback and trigger the alarm sound first (stop the current playback by sending 0xFE, then send the alarm command);

• Loop playback: The low battery prompt adopts the loop mode (send the F2 command 20ms after sending the voice command, Section 4.1 of the manual) until the user replaces the battery.

2. Voice Update and Debugging

• User-independent update: Connect the chip's RX/TX pins (Pin2/Pin3) through a USB-to-TTL module, to download audio files, supporting brand owners to update voice packs later (such as holiday greetings);

• Debugging convenience: Monitor the playback status through the BUSY pin, and use a logic analyzer to verify the one-wire serial timing (25ms command interval is recommended, Section 3.2 of the manual) to reduce development and troubleshooting time.

3. Low Power Consumption and Stability Assurance

• Dynamic power consumption control: Enter ultra-low voltage mode through the F0 command during non-interactive periods. When the main control MCU needs to wake up, it only needs to pull the DATA line low for 10ms (Section 4.3 of the manual);

• Power fluctuation protection: Connect a 105 capacitor externally to the VBAT pin (reference circuit in Section 2.4 of the manual) to avoid voltage fluctuations during speaker operation affecting the stability of the main control.

IV. Core Advantages of the Scheme

1. Cost and Space Optimization

• High cost performance: Compared with traditional OTP voice chips, KT148A supports reprogramming (no one-time burning required), reducing trial production costs; built-in storage and power amplifier functions reduce peripheral components, and BOM costs are reduced by about 20%;

• Small package adaptation: The SOP8 package (size about 5mm×6mm) can be directly embedded in the electronic lock main board, adapting to compact structure design.

2. Usability and Expandability

• Flexible voice customization: Users can replace voices by themselves through serial port tools (no professional equipment required), supporting multi-language package switching (such as Chinese/English/dialect), adapting to the global market;

• Function expandability: The voice address can be expanded through the F4 command (Section 4.5 of the manual), supporting more than 223 voices to meet the complex scenario needs of high-end electronic locks.

3. Low Power Consumption and Reliability

• Battery life advantage: Standby power consumption is 25μA, ultra-low voltage mode is 1.7μA, and 18-month battery life can be achieved with a 4000mAh lithium battery;

• Industrial-grade stability: Operating temperature is -40℃~+85℃, ESD contact discharge is 4kV (FAQ 8 of the manual), adapting to extreme environments such as humidity and high temperature.

V. Application Scenario Expansion

• Temporary authorization prompt: When a tenant obtains a temporary password through the APP, trigger the voice prompt "Temporary password has been activated, valid for 24 hours";

• Anti-pry linkage alarm: Cooperate with a vibration sensor to trigger the voice "Pry-proof alarm, synchronized to the mobile phone" and link the main control to send alarm information to the user's mobile phone through the one-wire serial port;

• OTA voice upgrade: Receive voice packs through the electronic lock's WiFi module, then forward them to KT148A through UART to realize "voice update without disassembling the machine".

VI. Summary

With "low cost, low power consumption, and easy development" as its core advantages, the KT148A voice chip provides a complete solution for intelligent electronic locks from "basic voice prompts" to "scenario-based interaction". Its flexible control methods, customizable voice content, and compact hardware design can not only meet users' needs for interaction experience but also help manufacturers shorten the development cycle and reduce costs. In the future, combined with technologies such as voiceprint recognition, it can also expand innovative functions of "voiceprint unlocking + voice feedback" to further enhance product competitiveness.

Target Customer Groups

Intelligent electronic lock manufacturers, smart home system integrators, security equipment solution providers.