2.4g wireless mouse
With the development of wireless communication technology, the short distance wireless communication area appeared in the Bluetooth, RFID, and WIFI technology. These technologies used in embedded devices and PC peripherals.2.4g wireless mouse and keyboard use 24 ~ 2.4835 GHz radio frequency band, the band of most countries in the world are unlicensed use, the wireless product popularization cleared away the biggest obstacle. USB interface system using 8 USB multimedia keyboard encoder systems as the core. The mouse, keyboard and other HID devices for low speed equipment, so the receiver can simultaneously realize the mouse and keyboard data from PC two-way transmission.MCU first must have a low speed USB interface, and at least 3 support (including O endpoint endpoint).USB USB standard enumeration process is a very important "action" or "process". This action will let PC know what USB device connected to and cut contains various kinds of information. To complete a device enumeration process, need to perform many of the data exchange and the device request.
2.4g wireless keyboard
The user can quickly into sync with the world of radio design, shorten the design and production time, and has perfect performance, can replace the Bluetooth technology.2.4g wireless keyboard, mouse and other receiver mainly realize the HID equipment on PC enumeration recognition process and receive wireless mouse or keyboard to send data (including the key value, the mouse up and down and move around and so on), and the received data through USB interface for PC machine, the realization of the mouse and keyboard wireless control function. The receiver is composed of USB interface part, MCU and wireless receiving part.
USB- signal line and 1.5 K ohm pull-up resistor
As a result of the mouse and keyboard device belongs from the equipment, it should be the USB- signal line and 1.5 K ohm pull-up resistor. MCU reset circuit by R108 and C105 consisting of RC integral circuit to realize the power on reset function. Electric moment, since the capacitor voltage can't mutation, so the reset pin is low, then capacitor start slow charging, reset pin potential began to rise, and finally goes high, to complete the chip power on reset. If the device power supply voltage drops to 0.9 V ~ VLVR range and that more than 1 of the time MS, then LVR will automatically reset device. It should be noted that for the device reset circuit, still should add 1 diodes. If not this diode, equipment in the first use of normal reset, but in later use but not normal reset, reason is the capacitance of the charge could not release, and the diode can go through the whole circuit fast release capacitor charge.PCB design of the system is good or bad, directly affects the performance of the system. In the design, consideration must be given to all kinds of electromagnetic interference, pay attention to adjust the resistance, capacitance and inductance position, with special attention to the location of the capacitor.
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