【Training Camp】Fancy atmosphere small table lamp 567883A

 

The left side is Pauling's type and the right side is Kekulé's type. Picture source is Baidu Encyclopedia.

• So here comes the question. Kekulé-style wires can use ceramic filaments or other COB filaments, but what about the ring in the middle of Pauling-style wires? After struggling for a long time, I chose WS2812 lamp beads for a circle.

3. Characteristics

• After I finished drawing the outline, I discovered a very embarrassing thing: the space was too small to accommodate other structures, so I settled for the next best thing and used two PCBs, with the upper layer being the light board and the lower layer being the control board. The two are connected through copper pillars, and the copper pillars also serve as conductors, so there won't be a bunch of messy flying wires. But then I discovered a very embarrassing problem: the Tuya module I chose was WBR3D, but Tuya's 0-code development function did not include the control of WS2812 lamp beads, but fortunately it left a serial port, which can be used with communicate with other microcontrollers. But what microcontroller to use?
• Because the development cycle is short, and I am pretty good at it, I chose the ATmega328P chip as the slave computer. I flashed the Arduino Bootloader and used the Arduino IDE for development, which was convenient and fast.
• But here comes the problem. The module level of Tuya is 3.3V, but the level of 328P is 5V. The levels of the two are different. Although there should be no big problem if they are connected directly, we still add another level for the sake of conservatism. conversion function
• It is safer to use a transistor here. Although using a resistor to limit the current is not a big problem, just choose either one.

• As for the debugging of 328P, the serial port chip chosen is ch340c because it is cheap; and in order to download and debug the program without conflict with Tuya module communication, soft serial port communication is used to communicate with Tuya's chip.
• Since I chose to use Arduino IDE for development, the purchased Atmega328P generally does not come with an Arduino bootloader and needs to be burned by myself, so I added a standard burning interface to burn the firmware by myself.

• As a desk lamp, how can it be used only by plugging in the power supply? Naturally, it needs to add a battery. As for what charging chip to use, I thought about it for a long time on Lichuang Mall and decided to use Yingjixin’s IP5306 chip. , the reasons are as follows

1. First of all, it does not have any fast charging protocol, but it can run up to the maximum USB current of 2.1A, so there is no need to worry about the power. At the same time, it can be safely connected directly to the serial port chip without worrying about burning the chip;
2. Then there is the built-in 5V synchronous boost, which supports charging and discharging simultaneously, eliminating the need for isolation of input and output;
3. The power of the boost circuit is large enough, and the maximum output current is as high as 2.4A, which is enough to feed the filament;
4. The peripheral circuit is simple and easy to design;
5. Comes with 4 LED lights for power display.

• Now that there is such a high-power charging chip, and for maximum compatibility, a dual USB port design is adopted, which is suitable for more people (in fact, I also want to add a Lightning interface)

The above is the schematic diagram and PCB diagram of the dual USB ports.

• So back to the question that everyone is most concerned about, what is ceramic filament?
• I borrowed a picture from a Taobao seller (the actual picture is not out yet)

SY8088 circuit

Then the rated current of each filament is 200mA, and when it encounters a "double bond", it can be as high as 400mA. In theory, it can be controlled using an S8050 transistor. However, the maximum output current of the S8050 is only 500mA. In order to avoid extreme situations, I used the S8050 transistor as the pre-driver and the SI2305 as the real "switch". In this way, the theoretical current that can pass through is as high as 4.1A (although it is useless). But six sets of filaments still look spectacular like this.

As for the power supply of the filament, I used copper pillars to connect the upper and lower plates, so that there are no exposed wires. It looks very simple and has a cyberpunk aesthetic after lighting it up.

Control panel front	Back of light panel	family portrait

The front of the welded light panel	an angle	another angle	another angle

Only open the "single button" filament	Only open the "double-bonded" filament	Purple ambient light with lighting function	Blue ambient light with lighting function

1. Although there are soldering pads reserved on the upper and lower sides of the lamp board, try not to solder all the filaments, because to be honest, the power of this lamp is quite high and there are many filaments. It is probably too much for DCDC to solder all the lamps, even if you change to a DCDC. , the maximum output current of ip5306 is only 2.4A. Even if you change the charging chip, it doesn't make much sense, the battery capacity is only that big. And now that the light is turned on to maximum power, it is very bright, and the entire dormitory is illuminated as if it were daytime. Therefore, the reserved pad positions are only for the upper and lower parts. If you feel unsightly, you can delete them.
2. The light board and the control board are connected using M3 copper pillars. Note that they cannot be replaced with plastic pillars because the copper pillars also serve as conductors. The six surrounding copper pillars are the positive electrode of the filament, and the middle one is GND. The power supply and data transmission lines of WS2812 use a single pin header and Dupont wire to connect the upper and lower boards.
3. The code is not open source for the time being, because there are always small bugs in the communication with Tuya. It is speculated that it may be because Atmega328P does not have serial port interruption. And there are too few customization functions in Tuya (maybe I’m just too good at it). And the panel SDK of Tuya is too difficult to use. The panel I use is the ugly debugging panel, which I can’t even stand.
4. Ceramic filaments are really really easy to break. This is not an alarmist, so please handle it with care. When picking it up and putting it down, try to hold the copper pillar instead of the filament, otherwise it will break easily (mine has been broken four times). Five of them)
5. When welding, the negative electrode of the lamp can easily touch the copper pillar of another lamp, so please be careful when welding. Remember to use a multimeter to check whether there is a short circuit after soldering. The consequence of a short circuit is to blow up the control mos tube.
6. Please try your best to buy all chips in Lichuang Mall (this is not an advertisement), otherwise the chips bought on Taobao may have some weird problems. For example, the ip5306 I bought this time will fall off when the load power consumption is high. , the mcu was pulled and shut down.
7. Please don't plug in two USBs at the same time, don't ask why.
8. If you want to use the local dimming function, please turn off the cloud control switch and turn the DIP switch of the light you want to turn on to "ON". Please note that the power of the MCU and Tuya module must be turned off, otherwise it may not work. In severe cases, the RH6616 chip may be burned out.
9. Because I was lazy and didn't have a suitable location, I didn't add a battery holder. Only two battery pads were left. You need to manually solder the wires. It is recommended that you use 18650 batteries. There is just enough room for one 18650 battery on the back.
10. Please note that there are components on the back, including a 22μ battery-side filter capacitor, two 10kΩ pull-up resistors, and an SHT30 temperature and humidity sensor. If you don’t want to use a temperature and humidity sensor, you can choose not to solder the resistor and SHT30. As for the filter capacitor...just be happy (doge).
11. According to the datasheet of RH6616, it is paved with grid copper because of the need for touch. It looks pretty good. And there must be a certain distance between the copper paving and the touch point, so it is recommended to manually frame the area without copper paving. I covered the touch points with oil for good looks. If you don't want to cover them, just change the solder mask expansion of this pad to a normal positive number.
12. It's still a problem with the RH6616. The 20nF capacitor and 5k resistor above are not commonly used capacitors and resistors. The capacitor can be replaced with 22nF or two 10nF capacitors connected in parallel; the resistor can be directly replaced with a 5.1kΩ resistor.
13. The filament, SY8089, IP5306 and other components may become hot after long-term use, so please try not to touch them.
14. The ceramic filament can still light up if it is broken, but it is very fragile, and there is a chance that only one side will light up. If the filament is broken during use, replace it with a new filament.
15. Please do not solder the transistors or resistors used for level conversion at the same time. Only one of them is required. It is unknown what problems will occur if they are all soldered.
16. Since the CH340C chip uses a 5V power supply, please connect a 10nF or 100nF capacitor in parallel with GND for V3 (the fourth pin). Please note that this is very important. Generally speaking, this is the reason why the serial port cannot be recognized.
17. Each power supply pin of WS2812 on the lamp board is connected in parallel with GND with a 100nF filter capacitor. However, some lamp beads do not need it, so you can solder it as needed.
18. There will be the next version of esp8266, which will be open source at that time, so stay tuned.