Completed

PROLego compatible building block walkie-talkie -OSHWHub Stars

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License

：

GPL 3.0

Creation time:2024-10-22 11:58:47Update time:2024-10-23 06:01:03

Description

Project Description

Overall description of the project:

A walkie-talkie module that is compatible with Lego-like building blocks and includes a host module, a switch module, a speaker and microphone module, and a PTT button module.

The connection between modules uses Lego PF parts cables and uses Espressif ESP32 2.4G module communication.

Open Source Agreement

Open source agreement description:

GPL 3.0

Project Related Functions

A walkie-talkie module that is compatible with Lego-like building blocks and includes a host module, a switch module, a speaker and microphone module, and a PTT button module.

The connection between modules uses Lego PF parts cables and uses Espressif ESP32 2.4G module communication.

Project Properties

This project is made public for the first time and is my original project. The project has not won any awards in other competitions.

Project Progress

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Every step is slow, every step is learning.

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2023-3 Complete the PCB design of the first version of the core module, and complete the hardware verification with manual welding.

2023-5 Complete switch module PCB and shell design.

2023-6 Complete PTT button + LED independent module PCB and shell design.

2023-7 Complete speaker and microphone module housing design.

2023-9 It took several months to continuously adjust the PCB and the adaptation of each 3D housing.

The PCB design has been completed, and the module shell design is 95% complete. Inter-module assembly accuracy testing, software testing and 3D design optimization are in progress.

2023-10 Complete assembly test.

Design Principles

Software communication principle : The walkie-talkie uses the Espressif ESP-NOW protocol to implement 2.4G voice communication between ESP32 modules. The communication method is simplex mode.

ESP-NOW: Using the ESP-NOW protocol, the protocol supports one-to-one communication, one-to-many one-way communication, many-to-one one-way communication, and two-way communication, and can carry up to 250 bytes of payload. The intercom captures audio transmissions in a maximum size of 248 bytes.

Inter-module communication adopts the form of broadcast address. Multiple devices can join to receive audio when they are turned on, without configuration.

Audio sampling: 8K 16Bit audio data.

Appearance design principle: The entire walkie-talkie adopts a Lego building module design, which can be combined with Lego-like building blocks to give children an interesting way to play. The cables of LEGO PF parts can be used to extend the combination between modules.

Scenario application: Can be spliced together with Lego toy guns to realize indoor calls and collaborative fighting games among multiple children.

Hardware design principles:

Realize simplex communication between walkie-talkies. When walkie-talkie A presses the PTT button to start a call, walkie-talkie B receives and plays the voice synchronously. Voice reception is not supported when making external calls (can be optimized to duplex through code).

MCU: ESP32-WROVER-IE-N8R8.

Download circuit: CH340C.

LDO: HOLTEK HT7833

Charging: TP4056X-42-ESOP8, 1000mA 523450 lithium battery, charging resistance 2kΩ, current 580mA.

Codec audio codec : Everest-semi (Shunxin) ES8311 single-channel ADC/DAC, used for microphone voice collection and audio playback processing.

Power amplifier : Nsiway NS4150B ultra-low EMI, no filter required 3W mono Class D audio power amplifier, compatible with 4Ω 3W and 8Ω 2W.

Speaker : 4Ω 3W.

Microphone : C529894 INGHAi GMI4015P-30DB.

Software Description

Components: ESP-ADF V2.4 ESP-IDF V4.4, esp-iot-solution.

Espressif ESP-ADF audio component realizes audio reading and playback.

Esp-iot-solution provides PTT button press detection recognition and callback.

ADF Battery_service cooperates with hardware design to provide battery monitoring and low battery alarm.

Audio processing logic follows 3 audio paths:

(1) Sending path of voice information collected by microphone: [Mic]-->[i2s_stream_reader]-->[raw_reader]--[espnow_send]

(2) espnow receives voice playback path: [espnow_receive]-->[raw_writer]-->[i2s_stream_writer]-->[speaker]

(3) Prompt tone playback path (boot welcome + low battery reminder): [tone]-->[mp3_decoder]-->[filter_sample]-->[i2s_stream_writer]-->[speaker]

The audio playback path is switched through ADF pipeline break+relink.

Physical Display

3D printing does not have a painted version.

It shows red light when charging and green light when fully charged.

Design Considerations

1. The power monitoring part does not use a fuel meter chip, so the power estimation will be biased.

2. The charging current can be adjusted according to the RPROG resistance.

3. The download circuit power supply is disconnected and not soldered by default. When downloading is required, you can use a jumper to short-circuit the two 2.54PIN ports to reduce standby consumption.

4. The prompt sound needs to be burned separately. For instructions, refer to:

C:\Users\ABC\.espressif\python_env\idf4.4_py3.8_env\Scripts\python.exe C:\Users\ABC\esp\esp-adf\esp-idf\components\esptool_py\esptool\esptool.py --chip esp32 --port com6 --baud 921600 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 40m --flash_size detect 0x110000 ./tone/audio_tone.bin

5. Text-to-speech gadget: https://www.text-to-speech.cn/