Catherine Sui
This project designed according to HT82K629A.
HT82K629Ais an excellent USB keyboard dedicated chip, simple application, few peripheral circuits, directly connected to the computer can be used, do not need to download the driver and code control.
Step 1: Features
1 Communication mode
HT82K629A can support two communication modes, USB and PS2. You can use the USB data cable directly for normal use, or you can add a Bluetooth chip and serial port chip for wireless Bluetooth transmission (you are welcome to have creative transformation).
2 Crystal resonance circuit
In addition to 6M crystal vibration as shown in the schematic diagram, 12M crystal vibration is also compatible (note the first line from the bottom of page 2 of the manual).
3 The power supply circuit
The working voltage of the chip is 4.4V~5.5V, and it can be used for communication and power supply directly with the USB data line. It doesn't need to lift the voltage circuit, which is convenient!
4 Manual instructions
The chip manual is as long as 27 pages. If you don't do an in-depth communication test with the computer, you only need to see the key-value matrix table on page 20 and the circuit reference diagram on page 22. For other problems, you can refer to our circuit without too much attention
Step 2: Schematic Diagram Description
There are two power filter capacitors C1 and C2 in the figure. Also, R1 is used as the current limiting resistance of LED1. When the power is switched on, the LED will be on (this is the power indicator).
Step 3: Main Control Circuit
In the figure above, X1 is the crystal oscillator circuit, which is directly connected to the crystal oscillator. The size can be 6M or 12M.
R4 and R5 as reset circuits, r6/7/8 as USB circuits. LED2 case lock indicator, LED3 is the rolling lock indicator. As there is no small digit key in key 87, an unconnected identifier was added to Num pin of digital lock to indicate that this pin is not used.
Step 4: A Specialized Circuit
There are several minor problems to be noted in the key circuit. The first is that the direction of the diode is from the R direction to the C direction. If the key is connected backward, it cannot be trigged. In addition, the role of the diode here is playing a full key with no impact, can not be omitted.
Step 5: Schematic
Step 6: PCB File
engineerkid1
kamalkedin123
