With the continuous development of wireless communication technology, technologies such as Bluetooth, RFID, and WIFI have appeared in the field of short-range wireless communication. These technologies are constantly being used in embedded devices and PC peripherals. The 2.4 GHz wireless mouse and keyboard uses the 24-2.448 5 GHz radio band, which is licensed for use in most countries around the world, which clears the biggest obstacle to the popularity of wireless products. Users can quickly enter the world of wireless design that is synchronized with the world, minimizing design and production time, and delivering the perfect performance to replace Bluetooth technology.
1 system hardware structure
The 2.4 GHz wireless mouse and keyboard receiver mainly implements the enumeration recognition process of the HID device such as the mouse and the keyboard on the PC and receives the data transmitted by the wireless mouse or the keyboard (including the key value, the movement of the mouse up and down, left and right, etc.), and The received data is transmitted to the PC through the USB interface to realize the wireless control function of the mouse and keyboard. The receiver is mainly composed of a USB interface part, an MCU and a wireless receiving part. The system hardware block diagram is shown in Figure 1.
1. 1 USB interface section
The system uses the 8-bit USB multimedia keyboard encoder HT82K95E produced by HOLTEK as the core of the system. HID devices such as mice and keyboards are low-speed devices, so the receiver must be able to simultaneously transmit mouse and keyboard data to the PC in both directions. The MCU must first have a low-speed USB interface and support a minimum of 3 endpoints (including endpoint O). Considering the HT82K95E as the main control chip of this system.
The circuit diagram of the USB interface of this system is shown in Figure 2, where resistors R100, R101, R102, R103, R104 and capacitors C102, C114 and C115 are used for EMC. Since the mouse and keyboard devices are slave devices, a 1.5 kΩ pull-up resistor should be added to the USB-signal line.
figure 2
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