General introduction

This design mainly includes speech processing module, environment perception module, peripheral module, and information display module. The speech recognition module is mainly based on the SYN7318 module, and its main function is to use voice to control the corresponding peripherals or broadcast information. For example: light a lamp, adjust the color temperature, broadcast the current time, and broadcast the current temperature and humidity conditions.

Voice processing module

Mainly include microphone, speaker, SYN7318 module and DCDC power module. Because the power supply of 7318 requires 3.6VDC power supply, a separate DCDC module is required. The microphone and speaker are the input and output of voice. In addition, a ch340e is added for serial port debugging.

Environment sensing module

This module is mainly based on the temperature and humidity sensor aht10 module, because this module has high accuracy and is just right to use. In addition, there is a light intensity sensor BH1750 to identify the current light intensity.

Peripheral module

There are few peripherals, maybe just an RGB lamp bead or ws2812, a programmable full-color lamp bead, but what is essential is a 2.4-inch OLED display module. ~~~~

designing process

a failed start

The first version of PCB proofing is back: This picture shows most of the components on the front side soldered, but the BH1750 is not soldered. This one is the back picture. First of all, please ignore my scumbag welder. After all, I only had a soldering iron worth 8 bucks at the time. Here you can see that there is a chip that I removed. That's because at that time, the charging management IC has been burned. And, in the first version, for convenience, I chose to use ART-Pi to convert 5V to 3.3V to power the entire system. But it turns out I was wrong. If the ART-Pi is not installed, the system power supply will not be normal. After putting it on, it perfectly covered all the electronic components. If there was a slight mistake, I really had no idea what to do. It was crazy. In addition, my MOS tube was destroyed due to lack of electrostatic protection during the welding process, so this was a complete failure.

Reflect and improve

After learning from the pain, I decided to redesign the PCB and debug it step by step. First of all, correct the errors in the power switching circuit in the first version (the MOS tube is connected in the wrong direction, the source and drain are connected reversely, the external power supply can directly charge the battery through the parasitic diode of the MOS tube, although it passes through the diode The voltage has been reduced to about 4.2V) Change the power supply circuit of the voice module (in the first version, I refer to the design of the classic circuit in the data sheet, but the voltage I want here: 3.6V and ordinary voltage: 5V or 3.3V is different, so I missed drawing two sampling feedback resistors.) After a series of modifications, in order to facilitate debugging, I decided to abandon the 3.3V voltage output pin of ART-PI. In order to ensure the normal operation of the entire board, I decided to add a 5V to 3.3V LDO separately. However, due to my poor early wiring, the components were almost impossible to place, so I gave up this plan again and finally decided to use the CC2530 module on the front of the PCB as the 3.3V voltage provider for the entire board. This solves both the debugging problem and the power supply problem. So after making the modifications, I sent the board out again.

try again

After receiving the board, welding and debugging began. The first priority is whether the power supply to the board is normal.