1. Project description

This is a system board made with Hangshun HK32F103VET6. This system board integrates TFT screen interface, 8Mflash, SD card interface and WIFI module. Through these interfaces, users can expand some advanced applications, and also has onboard LED and The buttons are also a good choice for beginners, and there are two WS2812, which are very nice.

2. Highlights

First picture

1. There are SD card, WIFI, 8MB flash and screen interfaces on the board, which is enough to expand some complex applications.

2. There are two type-c interfaces left, one is the serial port and the other is ST_LINK (in order to reduce costs, it is not onboard and needs to be connected externally (you need to make your own connecting cable)). The USB port is also led out separately.

3. The leaded pin header interface is fully compatible with the Raspberry Pi interface or ART_PI interface, and can be well compatible with external expansion boards.

4. The screen interface is led out with an FPC interface (instead of a female header), which saves a lot of space and will be introduced later.

5. There are multiple buttons and LEDs on the board for testing during experiments.

6. There are two WS2812 onboard, which can add some cool colors to the project.

3. Schematic and PCB design

1. Main control

       Since the price of STM32 has increased very sharply recently, the original goods in Tunnel are also seriously insufficient. I learned that Hangshun's chip is fully compatible with STM32. Since domestically produced ones are available, why not replace it? I will no longer have to worry about chips in the future. This design uses the HK32F103VET6 chip. Why did you choose this one? I think that if you want to make a development board, it must not only look beautiful, but also be powerful in function. Small size is also a major feature.

Originally I planned to use a 144-pin chip like ZET6, because this can expand more peripherals, but later I learned that Hangshun did not have this chip, so I settled for the next best thing and used HK32F103VET6, and gave it a rough idea. , and it has a lot of functions (haha).

There is nothing much to say about this part of the schematic diagram. The crystal oscillator, reset, boot, filtering and power supply form a minimum system.

2. Power and Download

First of all, in the picture above, I used to use micro-USB ports, which really didn’t look good. This is my first time trying to use type-c, which uses a 6-pin interface (6P cannot transmit data, tmd, I only found out today that I am really screwed. I searched a lot of information on the Internet. I worked all day at noon today and removed a data cable, but it still didn’t work. I don’t care, let’s fly the cable first. The next version will be replaced with 16P. This is all experience), which is enough for my application. I used a total of 2 type-c interfaces and a miniusb. Some people want to ask why there are so many interfaces on one board. Here I will explain it to you.

2.1 ST_LINKDownload

First we get the board and we need to burn the program to the board. Since we want to burn the program, there must be a download interface. Generally, the interface is designed to be led out with pin headers or a direct onboard downloader. First of all, let me tell you why I don’t Using these two solutions, if you use a pin header to lead it out, it will be slightly loose when plugged in, which will make it difficult to use after a long time, and it will be very troublesome when connecting. The on-board downloader is naturally very good, but the cost increases not a little bit, because for people like us, there are usually several models of boards, and each one needs to be downloaded. Does each one need to have an on-board downloader? ? Based on the above circumstances, I chose to use a type-c interface (only a type-c cable and an st-link downloader are needed), which can be used on any development board without instability. Phenomenon.

See the picture below for the download line

2.2 Serial port 1

The same principle applies to the serial port. If there is a CH340 on the board, one costs one or two yuan. Not only is it a waste of money, but it also takes up the board's volume and affects the aesthetics. Just add a serial port to TTl module to one line. See the picture below for the serial port line

2.3 usb

The chip I use has a USB interface. USB is a very good interface, so it is natural to leave it aside. In order to distinguish it from other interfaces, miniusb is used (actually based on other people's, I think it may be like this), this You don’t need to make it yourself, just use the normal thread, which I won’t take pictures here.

3.WIFI

In my development process, WIFI is a commonly used thing. It can connect to Alibaba Cloud and Baidu Cloud to upload data, connect the computer to communicate with the host computer, and can also be used as an AP mode to interact with mobile APPs. Users can design according to their own needs. . So I think a WIFI is very necessary. But what kind of WIFI to choose? Currently, there are not many people involved in it, such as AP6212 series and esp series. Considering the cost and popularity, I finally chose the esp8266, which is also the one I am most familiar with (definitely considering comprehensive factors).

The original plan was to use the chip directly, then match it with peripheral circuits, and then draw the onboard antenna. Finally, I copied a schematic diagram. After I almost finished copying it, I gave up decisively (it was a bit complicated, difficult to solder, and the cost was not low). Finally, after comprehensive consideration, I finally chose esp12-f because I have two of them (the cost is not high). It's also a SMD, so it can be soldered directly to the board, which is very convenient.

Because it is the first time to use it, there are a lot of uncertainties, so the interface is left to facilitate subsequent testing and modification. There is no copper pouring underneath. This is what Mo Gong taught me. The training camp really gradually enriched my experience.

4.TFT screen

A screen can be a nice tool, but it's not necessary, so I don't have onboard female headers here. I think it's good to leave one interface, which not only saves money on the motherboard, but also greatly saves the area of ​​the board, and is also very convenient to use.

What I refer to is the interface of Wildfire, because when I study 32, I learn the videos of Wildfire, so now whether it is f1, f4 or H7, I only watch Wildfire, and things are naturally from Wildfire (I love Wildfire).

We all know that Wildfire's 3.2-inch development board has pin headers directly left, and there is no such interface as FPC. How to use it?

In order to solve this problem, it is natural to draw a screen expansion board yourself. Not much to say, just the picture

There is a header and FPC left on it, and it can also be directly plugged into the Wildfire development board. It should be noted that this is a 5-inch screen because I don’t have a 3.2-inch screen.

5. External expansion IO

Because most of the IO is occupied. And I don’t feel the need to print it. The interfaces here are all compatible with those of Raspberry Pi and ART_PI.

Raspberry Pi interface

ART_PI interface

my interface

In this way, the interface of my board can be compatible with the expansion board of Raspberry Pi and ART_PI.

6. External expansion board

Since I participated in ART_PI activities before, I designed an expansion board

This is an expansion board for a thermal printer. You can use this expansion board to print out Chinese characters, QR codes and pictures. It currently supports multi-line printing.

Here are some pictures                                                   of the front                                                   and side                                                   effects:

The expansion board can be completely inserted into this board, and the interfaces are all corresponding.

If you want to know more about it, you can click on the link below: Thermal Printer

4. Welding

I don’t have much to say about welding this one, just practice more and weld more.

Practice makes perfect

Everyone has a first time, it would be better to solder a few more boards.

5. Conclusion

Inspired by ART_PI, it is compact, powerful, beautiful and practical.

6. Complain

Why make a complaint at the end? Because I was holding back my anger and couldn’t buy the goods. Previously, I saw that there was no stock in the mall, so I went to Taobao to sell it. I bought one after another, but was finally informed that it was out of stock, and all ended up with a refund. This experience is really not good.

Finally, I hope that Lichuang EDA and Hangshun will get better and better. I hope that Hangshun will speed up production and stop being out of stock. I also plan to replace STM32 in the future!

work hard together! ! !