[Training Camp] Tuya Learning Omnidirectional Infrared Universal Remote Control-272650A

Project Introduction

This is a learning omnidirectional infrared universal remote control based on the Tuya module that can control a variety of home appliances with voice (activation of smart speaker control requires payment, 5,000 yuan is too expensive for individuals, but voice control can be achieved through Siri shortcuts ). Features:

1. Omnidirectional remote control
2. With learning function
3. Firmware development-free
4. APP development free
5. The power input adds a protection circuit
6. USB uses differential lines to lead out RX/TX to facilitate access to production test tools
7. After activating value-added services, it supports multiple smart speaker controls.

[Link to Tuya IoT development platform] https://auth.tuya.com/?from=https://www.tuya.com/cn/&_source=cbc30f99f7a6c4aebca6755c2fab437f (contains detailed development documents)

Key component selection

Master chip

The main control chip is Tuya’s WB3S. WB3S is a low-power embedded Wi-Fi+BLE dual protocol module developed by Tuya Smart. It consists of a highly integrated wireless radio frequency chip BK7231T and a small number of peripheral devices. It has a built-in Wi-Fi network protocol stack and rich library functions. WB3S also includes a low-power 32-bit MCU, 1T1R WLAN, a maximum frequency of 120MHz, built-in 256K SRAM, 2Mbyte flash and rich peripheral resources.

Infrared reception

The infrared receiver chooses the common HX1838 to realize the learning function of infrared remote control.

Infrared emission

A total of 7 infrared emission tubes are designed for infrared emission. The layout is that six of them circle around and emit diagonally upward, and one in the middle emits directly upward. This achieves omnidirectional coverage of the device obliquely above and directly above. The infrared emission circuit refers to the reference schematic diagram provided by Tuya. If calculated according to the forward voltage drop of 1.4V, the instantaneous current of a single channel will reach 220mA (total idea). Test it first, and then consider lowering the current later.

power supply

The most commonly used power supply is AMS1117, which provides 3.3V voltage output for the system.

Input capacitance

I used a 100uF chip ceramic capacitor here to support the instantaneous large current emitted by the infrared tube. The measured capacity is sufficient. If you switch to electrolytic capacitors, it is recommended to use capacitors above 16V 470uF.

protect the circuit

The protection circuit part is designed with a self-restoring fuse and a TVS diode to achieve overvoltage and overcurrent protection.

User interaction

User interaction consists of the following two parts:

• One button allows users to activate the network distribution function.
• One LED indicator light, used to display the distribution network status.

designing process

After the schematic was completed, there were basically few changes. Originally there were no test points, but later test points were added. The biggest change is the PCB. The original version wanted the button to be placed in the middle, which resulted in the module and infrared transmitter tube being placed on both sides of the board, and the module antenna was not on the edge of the board. After repeated consideration, we finally decided to place the module in the middle of the upper edge of the circular PCB and cut off the PCB at the height of the antenna. This made the board much more beautiful. Later, a 0ohm resistor was added to the separate infrared emission tube to facilitate the adjustment of the emission tube current later.

2020.12.3 Update:

1. Adjust the spacing and angle of the infrared tubes
2. Change keys
3. PCB layout slightly adjusted

APP interface

For APP, just use Tuya’s public version APP. Basic interface:

PCB 3D preview (Rev1.0)

shell

The shell is a bit of a headache. A decent shell from a certain product costs 27 yuan including shipping! 3D printing with transparent resin costs 100 yuan+! This price is too unfriendly to retail investors. You have to know that the finished graffiti universal remote control on PDD is only 28 yuan, and shipping is free! So I thought hard and searched for a long time, and found a more suitable thing: a powder box commonly used by girls. PDD is only 4.5 yuan with free shipping. You just need to make the holes yourself.

Physical map

Penetration test

Signal strength: Measured to be able to penetrate a TV cabinet made of frosted glass

speech ability

1. Siri (Wall Crack Recommendation) : Set "one-click execution" in the Tuya APP (turn on the TV - turn on the set-top box - delay 40s - set-top box opens the specified channel), and then add it to the Siri shortcut to automatically turn on the TV + automatically turn on Set-top box and wait for the set-top box to start up and then open the designated APP (achieved with Dangbei desktop digital shortcut or through key combination)
2. Tmall Genie (generally recommended): You can automatically turn on the TV + automatically turn on the set-top box by combining commands. However, it does not support delayed startup of the APP, because the voice delay command of Tmall Genie can only be 1 minute at least, and it does not support set-top box button operation.
3. Xiaoai classmates (highly not recommended). When Mijia is updated to the latest version, it can only synchronize with the TV, but not with the set-top box. So only the TV can be operated.

Tuya adds "one-click execution" to Siri's shortcuts to enable turning on the TV + turning on the set-top box + delaying the opening of the designated APP	Tmall Genie can turn on the TV + turn on the set-top box through a combination of commands

Pity

After the welding was completed, I found that the board still had some regrets:

1. After adjusting the angle of the infrared tube, there is some interference with the buttons. In the next version, you can consider canceling the network configuration button or adjusting the size and position of the button. (The current document has been adjusted)
2. There is a problem with the rotation angle setting of the infrared tube in the upper right corner, which makes it difficult to adjust the direction. It needs to be improved in the next version. (The current document has been adjusted)
3. Tmall Genie can perfectly synchronize all added infrared controlled devices (one TV and two set-top boxes), but it cannot operate the set-top box buttons with a delay. However, Xiao Ai can only synchronize the TV, but the set-top box cannot be synchronized.

Improvements planned for next version

1. Add battery and charging management circuit (specifically, it depends on the power consumption, after all, it is a WIFI module...)
2. The connector is changed to type-c
3. Added USB power indicator light. Otherwise, it feels weird not knowing whether the device is running after powering on. Maybe it can be reset in the firmware.

See the attachment for the video (my video must be the most popular on OSHWHub, hahaha ^_^. Please wear headphones to watch the video for the best sound effect, Hollywood blockbusters are coming)