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Std edition GaiZhongGai-Keyboard-68+4PRO

Profile:The KEYBOARD uses an bargain CH551G MCU, has a unique matrix circuit, and supports OpenRGB ,and comes with a USB hub .

License: GPL 3.0

Published Time: 2022-06-29 07:45:53
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The project debuted on the Chinese version of the forum OSHWHub

In Chinese, this name is described as bargain among bargain goods, which means very bargain.

Place a common SCM configuration comparison table with QMK scheme

MCU model STM32F103C8T6 GD32F103C8T6 ATMEGA32U4-AU CH551G
lcsc code C8734 C77994 C44854 C108958
unit price(2022/6/24) US$ 7.6784 US$ 2.5877 US$ 23.4282 US$0.4851
encapsulation LQFP-48 LQFP-48 QFP-44 SOP-16
I/Os 37 37 26 12.5(RST feet can only be read when half)
bits wide 32-Bit 32-Bit 8-Bit 8-Bit
core ARM® Cortex®-M3 ARM® Cortex®-M3 AVR C51
ROM 64kB 64kB 32kB 10kB
RAM 20kB 20kB 2.5kB 0.75kB
EEPROM None (but can be simulated in FLASH) None (but can be simulated in FLASH) 1kB 128B

If you make a copy of your work, for example by selling it on eBay and making a profit, please pay $0.50 per copy as a commercial license fee.

Due to the inconvenient payment method, if you are not in China and want to award this project or pay the authorization fee, please enter the Sponsorship of openRGB and take a screenshot in the comments section. Thank you. Taiwan compatriots please send money to me.

1.function Introduction

Usually state


Press the FN

keyboard-layout (FN).png

2.Hardware Introduction

This is the circuit of the mechanical keyboard on the market (QMK's scheme is such), a typical matrix keyboard with anti-keystroke diodes.


This is my new matrix keyboard scanning circuit


If you analyze the circuit with ideal diodes, you will get confused,

while pressing S1,S3. Uio2=Uio3=0V when scanning IO1 bit low? This will read S1,S2 press???


This is the voltammetric characteristic diagram of onsemi 1N4148, and note that the horizontal axis is exponential.

It can be seen that there is a positive guide voltage drop of 500mV even at the lowest current of 0.1mA.

Combined with the above questions, it can be inferred that Uio2=0.5V and Uio3=1V.

At this time, we will check the MCU electrical parameters

屏幕截图 2022-06-12 162819.png

This is the technical document of CH552G. It is clear which supply voltage to choose.

Then through the real machine test, it is necessary to add the pull-up resistance to increase the diode conduction current and increase the voltage drop to obtain a more stable scanning detection effect.

3.Assembly note

The bottom plate is fixed with solder welded copper nut


Some holes need to plug screws in advance, and then weld switches


4.Write the firmware

If the software is opened in Chinese, please turn on this setting to switch to English mode


To burn the firmware, perform the following operations. Before the fifth step, press BOOT to insert the USB and release BOOT


design drawing
schematic diagram
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