DIY ESP32 Pixel Weather Clock: An Open Source Project

Introduction

The new year’s DIY activities for electronic engineers have begun, and I am here to witness the creativity of all the experts! Thanks to the Breadboard Community for providing a platform for technical exchange.

The open-source address for the pixel clock project: https://gitee.com/laoguaige/esp32-s3-r8-n8-pixel-clock

1. Complete Display

2. Hardware Design

2.1. Complete Schematic

2.2. Power Supply Section

In the first version, FM5324G was used as the controller. It is an integrated power management IC that includes lithium battery charging management, battery 5V boost output, battery level detection, and LED battery indication.

However, it was found that using an 800mAh battery, it would run out of power after just 10 minutes. Therefore, the power management section was discarded, and power was supplied directly through the TYPE-C interface.

Current version:

First, since the voice module requires a downloading device, the TYPE-C interface data connection was directly connected to a CH340N (the device U9 in the image, Lichuang Mall number C2977777). Next, I will explain each component.

1. R56 and R57 are required by the USB protocol, and must be 5.1K, which involves PD spoofing voltage output; the specific reason can be found online.

2. D8 and D7 are ESD protection devices to prevent static electricity from damaging subsequent devices; these components can also be omitted.

3. VBUS is connected to 5V through a short circuit symbol, indicating that this TYPE-C input is 5V; this is my personal habit, and I usually mark 5V directly at the USB.

4. U9 is the previously mentioned CH340N, which is a chip that converts USB to UART; our voice recognition module is downloaded via UART.

5. C26 and C27: C26, as indicated in the CH340N datasheet, requires an external 100nF capacitor at the V3 pin when the CH340N voltage input is 5V; a 100nF capacitor should also be added at the VCC.

6. R27 and D1 are recommended to prevent voltage backflow to the CH340N through RXD and TXD pins, suggesting a current-limiting resistor on the RXD pin and a reverse diode on the TXD pin to prevent current backflow.

7. D2 is also an ESD device to prevent damage from sudden high voltage caused by static electricity or lightning; adding ESD devices can effectively prevent sudden high voltage from burning out the equipment.

Summary: It is powered via USB and can also download voice recognition firmware through USB.

2.3. Main Control Section

Since this project involves a lot of networking, the best option is to use the highly compatible Espressif ESP32. Fortunately, I have an ESP32 development board, specifically the Lichuang ESP32S3R8N8 development board.

There is not much to say, just power the development board with 5V; the board has an LDO, and after inputting 5V, it will output 3.3V. It is important to note that I used the BOT pin to connect a button, which makes it easier to enter upgrade mode and erase memory in case of debugging failures.

2.4. RTC Clock Section

A common RTC clock module DS1302 is used. Its characteristics are as follows:

The schematic design is as follows:

DS1302 requires an external 32.768KHz crystal oscillator as a clock, which is the X1 device in the diagram. To ensure stability and accuracy, load capacitors are added to the input and output of the crystal oscillator; according to the crystal oscillator’s manual, 12pF load capacitors are added, which are C8 and C9 in the diagram. VCC1 is the power input for the backup battery; if you want the DS1302 to continue running when the device is powered off, you must connect this B1 battery holder, which is connected to a button cell. C7 is purely for filtering. The other pins of the DS1302 are control pins, which are connected to the development board pins for easy control.

2.5. Temperature and Humidity Collection Section

A common temperature and humidity sensor DHT11 is used. Its characteristics are as follows:

Schematic design

For the DHT11 data pin DATA, a pull-up resistor must be added to keep it high when idle. According to its datasheet, a 4.7K pull-up resistor R12 is chosen. The DHT11 supports a voltage input of 3.3V to 5V; since the development board operates at a 3.3V GPIO voltage, to ensure stable communication, the data pin DATA of the DHT11 is also kept at 3.3V, and the input voltage for the DHT11 is 3.3V.

2.6. WS2812 RGB LED Matrix Section

The WS2812B full-color soft pixel screen, 32 * 8 pixels, was purchased for 36 yuan on Taobao.

Schematic design:

WS2812 is a single-wire device, and each LED contains a driver circuit, allowing control of many LEDs simultaneously. However, to be safe, a 1000uF capacitor is added at the power input VCC of the WS2812 RGB LED matrix to prevent insufficient voltage and current when the matrix lights up. With the capacitor, if there is insufficient voltage or current, it can draw power from this large capacitor.

2.7. Audio Collection Section

Regarding analog signals, I am not very familiar, but here is a reference circuit for an audio collection module: MAX4466 audio collection module. Interested friends can search on Taobao.

Schematic design:

The actual effect seems not very good, but it can barely be used…

2.8. Button Section

In the software section, a button is used to control the UI interface switching. However, although I have used a button, my casing is not well done, which means I have to open the casing to press the button to switch interfaces… Please wait for me to improve or replicate it.

2.9. Brightness Collection Section

A resistor and a photoresistor are used to collect light brightness; the photoresistor will automatically adjust its resistance based on the light brightness. Why add the 1K resistor R58? Because the photoresistor may drop to 0 resistance due to light, which would short-circuit 3V3 and GND, so R58 is added as a load. Even if the photoresistor is 0 ohms, the presence of this load resistor R58 will prevent a short circuit.

2.10. Vibration Motor Section

A motor, also known as a motor, is easy to understand; it rotates when powered with positive and negative voltage. However, due to its structure, a vibration motor vibrates due to centrifugal force when it rotates.

2.11. Voice Recognition Section

For voice recognition, I used a module called SU-03T, which has recently become popular due to its simple operation and convenience. Voice command configuration can be done easily online.

Note that if you buy a standalone module, you will also need to purchase a speaker and a microphone (mic).

The speaker I bought from Lichuang Mall is: C530532

The mic is also: C234013

Below is the peripheral circuit for the SU-03T voice recognition module, followed by an introduction to each component:

1. Because this voice recognition module must be powered off during firmware download, a switch (SW1) is added to facilitate this operation.

2. C19 serves as an energy storage capacitor; since the voice recognition module consumes considerable current, a 10uF capacitor is added to power it when there is no current.

3. The microphone in the voice collection block diagram is a -32DB microphone, also known as a mic.

4. SPK1 is the speaker.

5. The 03TTXD and 03TRXD in the diagram are connected to the serial communication lines of the CH340N, and the voice firmware is downloaded through these two lines.

6. B2TX and B3RX are connected to GPIO13 and GPIO12 on the development board; the development board sets these two pins for serial communication, and the voice module also sets B2 and B3 for serial communication, allowing data to be transmitted between them. This is important because this voice module can only set B2 and B3 for serial communication.

Voice recognition firmware download has been mentioned earlier regarding the power supply. The USB interface has a communication device CH340N for the voice recognition module firmware download, as shown in the image:

3. Shell Section

3D file download: https://gitee.com/laoguaige/esp32-s3-r8-n8-pixel-clock/tree/master/3Dfile

Since the physical object is large, the printed shell needs to be separated into left and right parts.

LEDGrid2x.stl is a light bar, requiring two parts to be printed and assembled together;

Note: The light bar must be made of black material, whether choosing black material during 3D printing or later spray painting it black; remember to use black for the light bar! Otherwise, the visual effect will be greatly diminished.

frontFrame2x.stl is the shell frame, requiring two parts to be printed and assembled together;

Housing.stl and Housing_noV.stl are the same part; choose one for printing, as both are costly and should be printed judiciously;

To assemble the complete shell, you also need to purchase a black acrylic transparent panel to block light!

Production specifications: Black tea-colored transparent acrylic 95×330×2mm

Actual effect:

4. Software Section

Due to the extensive software section, please refer to the documentation for each module’s example in the Gitee repository: https://gitee.com/laoguaige/esp32-s3-r8-n8-pixel-clock/tree/master/example. Here, I will directly inform you that the complete firmware configured through the software can be directly downloaded to the development board. Go to: https://gitee.com/laoguaige/esp32-s3-r8-n8-pixel-clock/tree/master/firmware, download the latest firmware, and open the ESP32S3 burning tool https://www.espressif.com.cn/zh-hans/support/download/other-tools to burn from address 0.

After burning, power off and restart. The next article will focus on: building the Gitee repository, installing the environment, displaying time with DS1302, displaying temperature and humidity with DHT11, showing cool UIs with WS2812 RGB lights, obtaining network time via WIFI-NTP, fetching weather via WIFI and displaying it, voice recognition and broadcasting.

END

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