Wireless remote control system for tower crane based on MSP430 and nRF905 (3)
source: "Electrical Engineering" Author: Yang Peng time: 2012-04-12-
hardware receiver circuit design and
Basically the same receiving circuit and the transmitting circuit, the wireless chip is operating in the receive mode. The crane system requires high reliability, caused by the receiving circuit malfunction to prevent interference, receiving the drive output using software coding, hardware decoding technology, which is corresponding to each relay action a digital code, the code of the decoder output, the output signal by the optocoupler isolation and inverter to drive the output to control the action of the relay. So the other signal output will be banned, also eliminates system due to power on (or off) the moment I/O port output uncertainty caused by misoperation.
The design of the system software
System software includes software transmitter and receiver. Effect of functional division of transmitter and receiver of remote control system performance greatly, to improve the system reliability, speed recovery at emergency fault occurs, all the logic control are realized in the transmitter, the transmitter sends timing transmission and interrupt transmission in two ways: when the button moves, using interrupt mode to send, according to the timing of transmitting in the subsequent period of time. The receiver only realize signal receiving, decoding and driving output, when 3 consecutive times not receive information, automatically shut down all the output receiver, to restore the initial state. The advantage of this is:
(1) for the transmitter button control to capture the reliable. When the interrupt signal if lost, the receiver out of control and maintain the original state, but the control information sent from time to time and the corresponding control.
(2) when the RF signal interference or transmitter failure and makes the receiver does not receive the control information, the receiver automatically shut down all output to recover the original state, expand the accident prevention, also can realize "the transmitter off or electric power shortage, automatic shutdown".
receiver
