Xi'an subway route NFC electronic business card map

Acknowledgments written above:

The design idea of ​​this project is inspired by the following project, and uses the NFC chip used in the following project. https://oshwhub.com/scarrr0725/ji-yu-nfcde-ming-pian-ji-ji-yu-a

Original design intention:

Since I will work and live in Xi'an with my daughter in the future, I have also been thinking about commuting in Xi'an recently, so I suddenly thought of making a PCB board the size of a business card to make it easier to see the subway lines in Xi'an. During the design process, I saw the project in the acknowledgment at Kaiyuan Plaza. I thought it would be nice to add NFC function to the subway circuit board and realize functions such as electronic business cards. So I drew on the above solution and designed this Xi'an subway line board with NFC function.

designing process:

There may be friends who also want to design a subway route map for other cities, so let’s talk about my drawing board process. First, I searched Xi'an's latest subway route map for 2020 on Baidu and used it as a standard to draw subway lines. As shown below: Next, I started to draw the PCB board: First, I determined the size of the PCB board. The size I designed here is 10cm*6cm. If you want it to be about the same size as a normal bank card, you can reduce it to 9cm*5cm and put it into a common protective card holder. Next is a cool operation of my own. It can be seen that the subway line map above is actually quite large. If the picture is hand-drawn, it will inevitably have proportional distortion problems, resulting in the overall loss of control. So here I imported the above picture directly into the PCB schematic diagram, and adjusted the imported size so that the height of the line just filled the PCB board. The schematic diagram is as follows. Next, in the layer options on the right, I changed the imported picture to the top-level solder mask, and then used the top-level line drawing to follow the picture, and drew the road map according to the proportion of the picture: the above for each site I created the circle by using the solid fill tool to draw two semicircles and combine them. After drawing the circuit diagram, create a window area directly on the top layer (red line and circle) (note that you must operate in the PCB schematic diagram) After creating the window, please hide the top layer to ensure that the window area is not missing. Finally, just add the silk screen and your favorite pattern. The circuit diagram is relatively simple. You only need to copy the NFC coil and arrange the four components (LED, capacitor, resistor, NFC chip) in the desired position.

Physical welding

For the convenience of welding, I chose 0603 packaged resistors, capacitors and LED patches. This part of the welding is relatively simple. It should be noted that the size of this NFC chip is very small, almost the size of two 0402 packages side by side, and it is very difficult to weld! ! ! ! ! (If you are discouraged from welding, you can try SMT patches. The disadvantage is that they can only be pasted in green and are a little expensive.) I used a hot air gun to solder the NFC chip, but it overturned in the middle. . . . . I made five boards to verify, and the first one welded successfully achieved the effect. However, the four boards at the back were seriously overturned. For some inexplicable reason, the lights could not be turned on for communication. It took several reworks to confirm that the NFC chip was not attached properly, and even a small misalignment would not work! ! ! Helpless, after reworking N times, we finally welded 4 finished products! (I bought 6 NFC chips, but when I used the hot air gun to blow them, the tweezers pressed too hard and two of them cracked! They cost 4 yuan each! Heartbroken!!)

Physical display

Comparison of the size of the back of the NFC subway business card and the Xiaomi Mi 8 mobile phone: Front of the NFC card: The characters are of suitable size and you can see the information of each site clearly. (The character settings made in the first version were too small to be seen clearly, so I increased the size.) Use the APP to write the direct WIFI function into the NFC chip: after scanning, a dialog box for connecting to the specified wifi will pop up directly. , this function is my favorite. It is suitable for keeping at home. When relatives and friends come to your door, you can directly scan the card to connect to the wifi without having to tell the password. The video of using the APP to write wifi information to NFC direct connection can be seen in the attachment. There are many other functions, so I won’t show them one by one. Here is a list: Of course, I think a more practical function is the electronic business card. You can add contacts directly by attaching NFC. This function is really cool, especially for some sales. The staff can directly ask customers to put on their electronic business cards and add their contact information, which is quick and convenient, and avoids the disgusting process of slowly reporting and entering numbers. The effect can be seen in the video attachment~ This project has been published in Zhihu, the link is https://zhuanlan.zhihu.com/p/134499491 , and there is also an open source platform interlink behind the article~