| Wireless data transmission is used very often in our daily production and life. There are many techniques for example like Bluetooth and infrared. We will choose the right technology according to our real application. This paper chooses the chip nrf2401 and it works in ism frequency band. Moreover it has strong capability of transmission in distance, and that its transmission distance is 30m to 100m is satisfied by most applications.Our work includes two aspects which are hardware and software. In software, we analyze the architecture of upper and downer machine software. Then we realize the system by keilc51. The communication protocol includes the data linker layer and application layer. The data linker layer realize the frequency hopping algorithm and the application layer realize the serial port and wireless transportation interface. In the hardware, we realize the serial and power supplying circuit. We design the circuit based on circuit of the development board., which we remove the burn-write circuit of rom. By doing so, we can reduce the surface of the target board. The design of hardware includes the electric circuit diagram and the printing circuit board diagram.There are many similar wireless data transition system is peer to peer system, which it's upper side machine sends order to down side machine then down side sends the data to the up. Our application needs one up machine and several down machines. For other words, the up machine asks the down machines in turn. But the sensors connecting down machines have different velocity of data transmission. Some down machines have no data to transmit when it get its turn. So it can help the down machine beside it. The down machine then has the role of up machine. We have one real up machine which connects the upper software. We call these systems mix mode systems. |
