Design and implementation of bus stop announcement system based on CC1110 single chip microcomputer

With the continuous development of information technology, people's demand for communication technology is getting stronger and stronger. Getting rid of the constraints of wired networks and realizing wireless communication has always been a concern for everyone. Today, wireless communication research is becoming more and more popular and widely used, making communication between people more convenient and faster, and having more market development prospects. At present, most bus arrival announcements are manually operated or semi-automatically realized, and the real wireless voice automatic announcement system and the so-called GPS satellite positioning intelligent announcement system are expensive and have not yet formed a market. The intelligent dispatching system is also only used in a very few large cities. The CC1110 single-chip microcomputer chip combines a high-performance DSSS (direct sequence spread spectrum) RF transceiver core and an industrial-grade compact and efficient 8051 controller. The realization of the bus announcement system based on the CC1110 single-chip microcomputer will make the bus announcement automatic, so that the driver can concentrate on driving, reduce fatigue, and improve the traffic safety factor. The platform prompts passengers waiting for the bus to get ready to board the bus in time, so that urban public transportation can operate better. Nowadays, buses basically announce stops manually, but the bus announcement system based on CC1110 single-chip microcomputer is affordable. To fully realize intelligent voice announcement, the demand is huge and the price is acceptable. Intelligence is a need of modern society.

1 Hardware design of wireless voice automatic announcement system
The bus announcement system based on CC1110 single-chip microcomputer is based on the high-frequency wireless module CC1110. The peripheral circuit of the high-frequency wireless module CC1110 is shown in Figure 1. The system is divided into two parts, one is mobile, that is, the on-board wireless system; the other is fixed, that is, the wireless system installed on the bus stop. The system hardware structure block diagram is shown in Figure 2.

The on-board wireless system receives the modulated signal sent by the station through the RF transceiver module inside CC1110. When it is within the coverage of the RF wireless transceiver (CC1110 is adjustable to 100m or 800m), the MCU confirms the signal, and the WT588D is responsible for broadcasting the name of the station to be arrived at, "XX station is about to arrive, please get off the bus and be prepared to get off the bus", and the OLCD screen displays "XX station is about to arrive, please get off the bus and be prepared to get off the bus", and at the same time sends signals including the bus route and the direction of the bus to the bus station wireless system. At this time, the passengers can use the button to remind the driver to get off the bus at the station. When the bus arrives at the station, according to the information of the door opening, the WT588D is controlled to voice broadcast the prompt "XX station is here, please get off the bus, please pay attention to safety when getting off the bus", and when leaving the station, according to the information of the door closing, the WT588D is automatically controlled to broadcast the name of the next station. The communication between the bus and the bus stop adopts a point-to-point communication mode; the CC1110 system of the bus stop keeps sending bus stop related signals through the RF of the high-frequency module, and the MCU detects whether the signal returned by the bus is received. If the signal is received, the bus stop will announce the bus number after confirmation, and at the same time use the OLCD display to display "bus about to arrive: XXX bus...", and light up the arrival signal light of the bus, reminding passengers to get ready to board the bus.
1.1 Features of the high-frequency module CC1110
The high-frequency wireless module CC1110 contains a true CMOS solution system chip (SoC). This solution can improve the requirements of low cost and low power consumption for ISM band applications. It combines a high-performance DSSS (direct series spread spectrum) RF transceiver core and an industrial-grade compact and efficient 8051 controller. The RF radio transceiver can operate in the 433 MHz and 868/915 MHz frequency bands, has excellent wireless receiving sensitivity and strong anti-interference, high-performance and low-power 8051 microcontroller core, and a programmable rate of up to 500 kBaud. The hardware supports CSMA/CA function, a wide voltage range (2.0~3.6 V), 1 conventional 16-bit timer and 2 8-bit timers. [page]

1.2 Voice module WT588D
WT588D is a voice microcontroller chip that can be repeatedly erased and burned produced by Guangzhou WeiChuang Technology Co., Ltd. WT588D allows the voice chip to be directly connected to the 89C2051 microcontroller, replacing the complex peripheral control circuit. The module adopts a three-wire serial port control I/O port extended output mode application circuit, and the circuit module is shown in Figure 3. I/O port P01 is defined as the DATA data port, P02 is the CS chip select port, and P03 is the CLK clock port. The microcontroller can control the WT588D voice module through three control ports. The microcontroller sends data F5 to the WT588D voice module, switching from the three-wire serial port control mode to the three-wire serial port control I/O port extended output mode, and maintains the last working state in the three-wire serial port control mode. The I/O port output voltage is basically equal to the input voltage of the module. The voltage of the VCC input terminal of the WT588D module must be guaranteed to be between 2.8 and 3.5 V. If the voltage of the module VCC is greater than 3.5 V, the internal memory of the module may burn out. When using it, just use the host computer software to burn the voice program into the module.

1.3 LCD display module OLCD12864
The display part uses a dot matrix OLCD12864 expansion board, which integrates OLCD, LED and buttons. The OS128064P model OLED has a resolution of 128x64 and can display in reverse colors. The OLED has the same function as LCD, with lower power consumption and larger viewing angle than LCD, and clearer display patterns. The 4 buttons on the board are usually used for menu selection. The OLCD LCD screen interface circuit is shown in Figure 4.

2 Important configurations of the CC1110 wireless part
1) Output power configuration The RF output power has two programmable levels. First, the dedicated PA_TABLE register can hold 8 user-selected output power settings; second, the 3-bit REND0.PA_POWER value selects the PATABLE use entry. This two-level function provides flexible linear rise or fall of PA power and ASK debugging shaping at the beginning and end of transmission. In each case, all PA power setting values ​​from serial number 0 to FREND0.PA_POWER value in PA_TABLE will be used.
2) Frequency Configuration CC1110 can work in the free frequency bands of 315, 433, 868/915 MHz. If the high frequency part of CC1110 starts to work, its working frequency band must be configured to these frequency bands (300-348 MHz, 391-464 MHz and 728-928 MHz). If you want to set these parameters, you need registers such as CHANNR, FSCTRL0, FREQ2, FREQ1, and FREQ0.

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3) Modem and data transmission rate configuration The modem can modify its modem mode to 2-FSK, GFSK, MSK, etc. by configuring MDMCFG4, MDMCFG3, MDMCFG2, MDMCFG1, MDMCFG0 and DEVIATN. The RF part of CC1110 is a programmable control rate chip with a maximum rate of 500 kBaud. Since the higher the rate, the greater the current consumption, considering the issue of energy saving, it is necessary to modify the data transmission rate accordingly when a high rate is not required.

3 System software design
This system software design mainly includes initialization module, wireless transceiver module, display module and voice control module. Initialization mainly completes the configuration of CC1110 high-frequency module input and output I/O, important configuration of wireless transceiver part, OLCD display initialization and voice chip WT588D initialization; the wireless transceiver part program is the key part of the system operation. The wireless transceiver protocol adopts SimpliciTI network protocol. SimpliciTI network protocol supports various network topologies, but it can still support point-to-point communication. This option can not only use access point devices to store and send messages, but also expand network coverage through range extenders to support multiple frequency hopping; the bus station announcement system based on CC1110 single-chip microcomputer works in the 433 MHz frequency band, and the data transmission adopts 2-FSK modulation mode, with CRC check, and strong anti-interference ability. The on-board wireless system and the platform wireless system transmit and receive wireless data through the RF part of the CC1110 high-frequency module, and perform related controls such as OLCD display control and voice broadcast control according to the received data. The program flow charts of the on-board wireless system and the platform wireless system are shown in Figures 5 and 6.

4 Conclusion
The intelligent wireless bus voice automatic announcement system based on the C51RF-PS system realizes a wireless intelligent bus announcement system that provides better services for drivers and passengers. It uses the cost-effective CC1110 wireless high-frequency module as the main control chip to reduce the system cost, and uses an external voice recording and playback chip WT588D. It also uses an OLCD liquid crystal module display.
This product has the characteristics of novelty, convenience, intuitiveness and reliability. Through software debugging and hardware testing, all parts of this system have achieved the expected functions. In addition, based on the design of the voice circuit, it can also be applied to various systems such as bus intelligent dispatching system, highway toll system, bank number reporting system, etc.