Abstract: This paper introduces a handheld monitoring device based on MSP430FG4618 single-chip satellite communication vehicle station. This device can complete the monitoring of antenna controller and satellite MODEM, realize various parameter setting, working mode selection and system status monitoring.
Keywords: vehicle station; handheld monitoring equipment; MSP430FG4618
introduction
The vehicle-mounted satellite communication earth station is a satellite communication station installed in a car. It utilizes the rapid mobility of the vehicle and can quickly reach the scene of the event to form a high-speed information channel to meet the needs of real-time communication. In order to ensure that all parts of the vehicle station can work normally, centralized control and monitoring must be carried out in the station. The function of the monitoring device is to monitor the status of various devices in the system, and can alarm and troubleshoot when a fault occurs.
In the past, the monitoring method for the on-board station was mainly computer monitoring. The RS-232 port of the antenna controller was connected to the RS-232 port of the computer inside the computer, and was monitored through the interface written by the software. The design of this paper is based on MSP430 MCU embedded handheld monitoring system, users do not need to carry a computer for monitoring, just connect the two RS-232 ports of the handheld device to the antenna controller and the RS-232 port of the satellite MODEM. Monitor and control operations.
Design principle and scheme of satellite MODEM handheld device
Hardware implementation of satellite MODEM handheld device
The handheld device has four main hardware parts:
1. MCU: MCU is the core part of the handheld monitoring device. It consists of MSP430FG4618 and peripheral circuits. MSP430FG4618 is a 16-bit ultra-low power MCU with 116KB flash memory, 8KB RAM, 12-bit ADC, dual DAC, DMA, 3 OPAMP and The 16-segment LCD uses an external 8MHz crystal oscillator (clock). The main function is to complete the keyboard detection, liquid crystal display and data transmission and reception according to the user's commands. It provides two duplex serial ports Uart0 and Uart1, which can realize asynchronous data communication with the antenna controller and MODEM, and can be extended to multiple UART serial ports with higher baud rate by UART multi-serial port expansion chip (SP2338DP) as needed. Because the interface display program occupies a large RAM and Flash, and requires a higher operation rate, the MSP430FG4618 series can meet the design requirements. The system supply voltage is 5V, and the 5V power supply can be introduced by the antenna control unit, and no self-supplied battery is required.
2. Keyboard: The keyboard circuit realizes input configuration parameter information, which is mainly controlled by the port P5.3~P5.7 of MSP430 and the matrix keyboard circuit controlled by P4.3~4.7 column. The keyboard input is used to capture the input of the keyboard. The keyboard part mainly includes 0~9 number keys, up and down left and right direction keys, confirmation keys, clear keys, reset/collection keys and switch keys.
3. Liquid crystal display: In the application of handheld devices, the human-machine interface is a very important part of the system. Since the liquid crystal display has the advantages of low power consumption, small size, light weight, ultra-thin, etc., the handheld adopts ST7920 Chinese character dot matrix LCD control / driver.
4. Alarm light: The alarm part is controlled by P4.3~P4.7 port. The 74HC245 is an extension of the input/output interface. The alarm circuit consists of four LEDs. LED1 and LED2 represent the current state of the antenna (lock/search). LED3 and LED4 represent the status of the receiver, tilter, polarization, etc. (normal/fault).
software design
The system software mainly adopts the modular design method, and divides all functions into main modules and functional modules. In the specific implementation, the combination of interrupt and query is adopted, and the design idea of ​​task scheduling is used. The task with higher priority is realized by interrupt, while the task with low priority is called by setting and querying the function module. . The whole system software consists of a main program, a receiving data processing program, a keyboard interrupt service program, a display program, and a serial port interrupt program. Among them, the keyboard detection program is placed in the timer interrupt, with the highest priority, followed by the serial data transmission interrupt program, the data processing and display program has the lowest priority, and the scheduling operation is performed by querying the flag.
For the software design of liquid crystal display, the ST7920 is mainly used for reading and writing operations. The ST7920 has two modes of drawing and non-drawing, and provides two sets of control instructions: basic instruction set and extended instruction set. In this design, the display of Chinese and English characters uses its own Chinese character code table, which is completed with the basic instruction set; the editing reverse display part is implemented by drawing mode and using the extended instruction set.
Conclusion
The handheld monitoring device is now in use in the ultra-small-caliber portable satellite communication earth station and the in-vehicle earth station system developed by Nanjing University of Posts and Telecommunications and Beijing Aikedi Information Communication Technology Co., Ltd. The on-site use shows that the device has complete functions, stable operation, good real-time performance, convenient operation and use, and has good application prospects.
:
Extra loading shock absorber Caster
Extra loading shock absorber Caster,Brake Caster Wheel,industrial caster and wheel
BENYU CASTERS & WHEELS CO.,LTD , https://www.benyucaster.com