Quoting Lichuang's official 87 keyboard to make a split 78 keyboard (left)

In the early stage, I received a set of split 78 keyboard casing from Xianyu, and I have always wanted to play with it by making my own PCB. I just happened to create an 87 keyboard, so I scanned the shell and positioning holes to generate a positioning plate. I am new to electronics and don’t understand a lot of things. I have been making changes for about a week (the GND automatic connection is not easy to connect, and I didn’t know what copper laying means in the early stage). The file on the left is modified as follows (I don’t know whether it is right or wrong. Please help me read it. (Bottom) 1. Because there is no need for lights, I deleted the circuits of the three lights, and deleted the light resistors and lights (I don’t know whether it’s right or wrong). 2. When GND is automatically connected, the wires always fly, so just add them in the schematic diagram. All GND points are marked with × to indicate that they are not connected, and then use through holes to connect the copper GND network during PCB production (not sure whether it is right or wrong) 3. Do the official names of 0.1U and 0.1u capacitors refer to 0.1 μF capacitors? 4. What are the ohms of the two official resistors R7 and R8?

HT82K629A is an excellent USB keyboard dedicated chip with simple application and few peripheral circuits. It can be used directly connected to the computer without downloading drivers and code control. Simply the best choice for DIY keyboard! Lichuang Mall sells dual in-line and SMD packaging types to meet all your needs! ! ! Attached is the mall chip purchase link: https://so.szlcsc.com/global.html?k=HT82K629A

Here are some key points that must be examined:

• way of communication

HT82K629A can support two communication methods: USB and PS2. It can be used normally by directly using the USB data cable. You can also add a Bluetooth chip and a serial port chip for wireless Bluetooth transmission (you are welcome to modify it if you are creative)

• Crystal oscillator circuit

In addition to the 6M crystal oscillator in the reference schematic diagram, the 12M crystal oscillator is also compatible (pay attention to the last line on the second page of the manual)

• power circuit

The working voltage of this chip is 4.4V~5.5V . It can communicate and supply power directly with a USB data cable. It does not require a step-up and step-down circuit, which is really convenient!

• Manual instructions

The chip manual is 27 pages long. If you don’t want to conduct in-depth communication tests with the computer, you only need to look at the key value matrix table on page 20 and the circuit reference diagram on page 22. There are not too many other issues that need attention. You can refer to us of this circuit.

Circuit design and sample making

• circuit design

Draw the circuit principle in Lichuang EDA. Regarding the schematic library and package library, you can use the official package library or the user shared library (thank you to the user for providing a large number of different styles of button packages). When drawing the schematic diagram, you give priority to using the Lichuang library . After creating the EDA basic library device , not only the style is unified, but also comes with a 3D model . Next, layout and design according to the dxf positioning board file (for detailed operations, you can see our live broadcast replay, etc., the link is below)

• PCB proofing

Which company is better at PCB proofing? For exporting Gerber, go to Jialichuang ! ! Jialichuang's 5 yuan proofing is simply a benefit to all mankind. Although this keyboard PCB file exceeds the scope of 5 yuan proofing, we still have coupons. There are many ways to obtain proofing coupons, such as participating in the open source platform's collection order, Sign-in gifts on the open source platform, proofing coupons given out during Lichuang EDA training, or rewards for users who give us constructive opinions or feedback . We fully support you who love to do things~

• Component purchase

When buying devices, choose Lichuang . There is absolutely nothing wrong with this choice. The devices on Lichuang Mall are all original and genuine and do not contain fake or shoddy products. No matter in terms of learning, preparing for competitions, participating in competitions, etc., a genuine chip can save us a lot of detours. Lichuang Mall, which delivers goods within four hours, has two major warehouses in Shenzhen and Jiangsu. The delivery is fast , you can choose the express delivery method, and it also has high-quality after-sales service. The most important thing is that Lichuang Mall has a lot of activities , and there are many more every month Brand coupons are just like giving away equipment! ! There is also a big gift package for new user registration ! ! !

(PS: The Lichuang EDA account is shared between Lichuang Mall and Jialichuang)

Here are a lot of pictures and videos coming

• Schematic description                                               

In the picture, C1 and C2 are two power supply filter capacitors. In addition, R1 is used as the current limiting resistor of LED1. When the power is on, the LED lights up (this is the power indicator light)

• Main control circuit

In the picture above, X1 is the crystal oscillator circuit, which can be directly connected to the crystal oscillator. The size can be 6M or 12M ; R4 and R5 are used as reset circuits, and R6/7/8 are used as USB circuits. LED2-digit case lock indicator, LED3 is the scroll lock indicator. Since the 87 keys do not have small numeric keys, a non-connection indicator is added to the Num pin of the numeric lock to indicate that this pin is not used.

• key circuit

There are several small issues that need to be paid attention to in the button circuit. The first is that the direction of the diode is from the R direction to the C direction. If the button is connected reversely, the button will not be triggered. If you find that there is no response when pressing the button during the test, you can check whether the diode Weld it well (you can directly short-circuit it to test the key function); in addition, the role of the diode here is to provide full-key rollover and cannot be omitted.

• PCB3D preview

• Physical map

Live playback of the complete video: https://www.bilibili.com/video/BV1XZ4y1x7ix

Full video of soldering PCB: https://www.bilibili.com/video/BV1Y54y19797?from=search&seid=3334337676173120982

Everyone is welcome to like, follow and collect! ! Three consecutive support! !

The following are the highlights of the video, click the link above for the complete video: