CAN PROTOCOL BASED CO2 MONITORING SYSTEM

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1 CAN PROTOCOL BASED CO2 MONITORING SYSTEM Sntosh V Totagi 1, Dr. U V Wali 2 1 PG Student, Department of VLSI Design and Embedded Systems, K.L.E.Dr.M.S.Sheshgiri college of engineering and technology,belagavi,karnataka,india 2 Professor, Department of VLSI Design and Embedded Systems, K.L.E.Dr.M.S.Sheshgiri college of engineering and technology,belagavi,karnataka,india Abstract Through the work of researchers and the development of sensor technology, sensors are being widely used for process control, monitoring quality, and assessing safety. In the industries such as food storage, agricultural & chemical, there is a growing demand for co2 sensor. The goal of this work is to design & develop highly automated CAN & Microcontroller based co2 level monitoring system to measure the co2 level in working environment & to detect the faults. The main aim of this project is to implementation for data communication based on CAN protocol by using ARM controller LPC CAN is a multi-nodes broadcast serial bus standard for connecting electronic control units (ECUs). Each node connected to bus is able to send and receive messages, but not simultaneously, based on priority at a instant only one node will transmit & receive. It is an embedded project and has the ARM controller LPC1768 as controlling controller. The CO2 sensor maintains the CO2 at the specified level. According to the Sensors the controller will gives to the CAN transceiver. It transmits and CAN transceiver receives and gives to ARM controller. It displays the data in the LCD. Due to such automated industrial control system effective control and industry safety can be achieved Keywords CAN, PIC18f458, MQ2, LM35 and GSM Modem. I. INTRODUCTION The evolving trends & technology have bought more safety & comfort in industry process. Initially CAN protocol was specially designed for vehicle automation but now a days it has been advanced to home automation, industry automation & so on. In industry automation, food & agricultural industry are rapidly growing, which requires a fully automated system to monitor & to control the various parameters. Co2 is one of the important parameter in food storage sector, because small variations in Co2 level results in beginning of spoilage. Hence Co2 sensors play important role in food industry to detect the starting of spoilage & estimate the suitable co2 level in the modified atmosphere. In recent era consumer demand has been increased towards food safety, quality & convenience, in order to meet the demands, it has become necessary for food & agricultural based industries to rely on sensors & robust serial communication protocol. Usually sensors used in food & agricultural industries will vary from the sensors used in traditional industries in-terms of measuring parameters & environment. Because to monitor gas level in these sectors the sensors should be capable of tolerating extreme temperature & pressure in working environment. Many micro-organisms and biological agents in agro, & food industry challenges to implement an automated system. There for monitoring of co2 level by smart system is becoming important in many agricultural dependent applications like composition of soil & carbon, monitoring bio gas mixture proportion, fruits freeze damage detection etc. Monitoring co2 level in food packaging is very important; hence it is largely used in controlled atmosphere. Change in co2 level indicates the damage. Co2 sensors are also used to detect safety & freshness of modified atmosphere. The smart systems which are capable of detecting 0.1% of All Rights Reserved 100

2 concentration, will detect the spoilage of stored grains, hence the need of co2 detecting system is increasing in agro & food industries. It is very important that the communication between sensor & control unit should be robust, to achieve fast serial communication between co2 sensor & controller unit, we are using CAN protocol, it is a bus which works on differential signals, as a result the electrical spikes are avoided & finally increasing the efficiency of system. Because of its high immunity towards electrical spikes & reduced wire complexity, CAN protocol is widely used in industry automation. OBJECTIVE The main goal of project is to design & implement real time co2 level monitoring system, for the modified atmosphere in food & agro based units. The all sensor nodes in industry are connected through single CAN bus, each co2 sensor unit frequently transmits data to master node, which is present in control room, the data received by master will be displayed on LCD. Each unit has unique identifier, which helps in distinguishing the node in which co2 level variation is occurred. LITERATURE REVIEW The Control Area Network (CAN) was created the German Automotive Can was specially designed for robust serial communication for automobile industries. In mid 1980 s, german automotive system supplier Robert bosh designed CAN for automotive applications, because of flexibility of this protocol, it is playing vital role in industry automation. In this paper Review of Research in Controller Area Networks Evolution & Applications wei Lun Ng discuss the design of communication hub interconnected to various nodes in industries. Due to vast advantages of CAN, it had shown a great surge of interest. Hence then it is widely used in factories, electronics, aviation, military & many other automotive industries. In the absence of host computer, CAN was designed to provide communication between microcontroller & devices. Paper gives brief knowledge on operating rules on CAN protocol, principles & architectures.can is becoming standard for transmission of data in automotive applications, because it is highly stable towards electrical noises, errors & also capable of auto-correction & managing bit mismatch in data. CAN is slowly becoming famous in various industries. II. SYSTEM HARDWARE DESIGN Fig 1: Block level review The project diagram consists of following major parts. 1) ARM cortex-3 LPC 1768 as master node. 2) MQ 7 gas sensor (co2 sensor) is connected to slave node. 3) CAN bus (Twisted pair wire). 4) Liquid crystal display All Rights Reserved 101

3 The master & slave nodes are implemented using LPC1768 controller. MCP2551 is a CAN transreceiver, which is used to drive larger loads. LPC 1768 controller pins CANTX1 & CANRX1 are connected to TXD & RXD pins of MCP2551 trans-receiver. The CAN bus implemented with twister pair wire, which is terminated with 120 ohm resistance at both ends. For maximum power transmission the bus is terminated with resistance value. As the bus length increases the data rate will decreases. The MQ-7 CO2 sensor to ADC initialized pins of LPC1768 or nodes, all nodes are connected to CAN bus via MCP 2551 trans-receiver. Based on filter design, the receiver nodes will receive the broadcasted message & lastly 16*2 inbuilt LCD is used to display received CO2 level. IMPLEMENTATION OF SLAVE NODE (SENSOR NODE) Slave node is implemented by interfacing MQ-7 gas sensor with eight data channel A-D converter. Gas & smoke is applied as a input to sensor, the main function of sensor is to determine the percentage of CO2 for applied input. The output of the sensor is fed to the op-amp device LM385 op-amp use for send the difference signal between reference voltage & output of the sensor, the reference voltage sent by the variable resistors & some biasing resistors. Figure 2: Slave Node Diagram ADC INITILIZATION In power control for peripherals register (PCONP) the 12 th bit PCADC should be made high to enable the ADC, Analog to digital converter is disabled when PCADC=0 or reset. The clock rate that to be supplied to ADC, is controlled by setting the pair of bits (pin 25 & 24) in pclksel0 register. The PCLKSEL0 default value will be zero, hence PCLK for ADC & other peripherals will be ¼ of system frequency. In A-D control register (AD0CR), the CLK DIV bit is used to divide the CLK for ADC. CLKDIV=FPCLK / (ADC_CLK-1). Pin function selects register (PINSEL1), the pins from 15 to 18 are used to select p0.23, p0.24, & p0.25 pins for ADC All Rights Reserved 102

4 LPC_SC->PCONP = (1 << 12); LPC_PINCON->PINSEL1 &= ~0x000FC000; LPC_PINCON->PINSEL1 = 0x ; LPC_PINCON->PINSEL3 = 0xC ; LPC_PINCON->PINSEL1 = 0x ; International Journal of Recent Trends in Engineering & Research (IJRTER) ANALOG TO DIGITAL CONVERTER RESULTS Result bits of A/D data registers (ADD0 TO ADD7) contain the most recent converted digital value. Further the digital data is written in to reg-val variable. Reg-val = (LPC_BASE+ADC_OFFSET+ADC_INDEX-Channel no) IMPLEMENTATION OF CAN In CAN implementation we discuss, CAN initialization, CAN transmission & CAN reception. LPC 1768 contains inbuilt CAN module with two channels CAN1 & CAN2. CAN INITIALIZATION In PCONP register, the 13 & 14 bit are made high to enable the CAN1 & CAN2 clk/power. Port0 pins (p0.0 & p0.1) are used for CAN1 & similarly port2 pins (p2.7 & p2.8) are used for CAN2. Initially CAN1 & CAN2 mode register bit RM is made zero to reset (RM=0). In CAN interrupt enable register, receiver interrupt is disabled by setting RIE bit = 0. RXERR & TXRR bits of CAN global status register (GSR) made zero to reset the error counter. LPC_SC->PCONP = ((1<<13) (1<<14)); LPC_PINCON->PINSEL0 &= ~0x F; LPC_PINCON->PINSEL0 = 0x ; LPC_PINCON->PINSEL4 &= ~0x0003C000; LPC_PINCON->PINSEL4 = 0x ; LPC_CAN1->MOD/* = LPC_CAN2->MOD */= 1; LPC_CAN1->IER/* = LPC_CAN2->IER */= 0; LPC_CAN1->GSR/* = LPC_CAN2->GSR */= 0; CAN TRANSMISSION Transmit identifier register (TID1) hold the 11 bit identifier of the next transmit message. Transmit data register (TDA1) contains 1 to 4 bytes of next Transmit message. Transmit data register (TDB1) contains 5to 8 bytes of next Transmit message. LPC_CAN2->TFI1 = ptxbuf->frame & 0xC00F0000; LPC_CAN2->TID1 = ptxbuf->msgid; LPC_CAN2->TDA1 = ptxbuf->dataa; LPC_CAN2->TDB1 = ptxbuf->datab; LPC_CAN2->CMR = 0x21; Figure 3: CAN TX Buffer All Rights Reserved 103

5 CAN RECEPTION Receiver identifier register (RID1) hold the 11 bit identifier of the next transmit message. Receiver data register (RDA1) contains 1 to 4 bytes of next Transmit message. Receiver data register (RDB1) contains 5 to 8 bytes of next Transmit message. Figure 3.4: CAN RX Buffer values IMPLEMENTATION OF MASTER NODE In this project only one slave node is implemented, hence it is for master to control. But as the number of slave nodes increases, the responsibility of master will also increases. The role of master is to send transmission request to slave node, from which the data is required. The sensor processed data is stored in slave node transmit buffer will be sent to master node. The master controller collects the data & displays it on LCD module. The CAN transmission, reception & initialization are same as that of slave node. Figure 4: Master Node Diagram. III RESULTS Micro vision tool provides micro vision debugger in which CAN dialog box helps us to observe the status of registers, value of buffers & preprogrammed identifier All Rights Reserved 104

6 Figure 5: General CAN Controller Registers Above figure gives view of changing values of CAN control registers such as mask ID, baud rate of communication etc. Figure 6: CAN Message Object Registers. This dialog box shows the status information of CAN messages. Figure 7: Review of Incoming and Outgoing All Rights Reserved 105

7 From above dialog box, we can observe the communication of nodes, which is also showing the received & transmitted messages. No or Number: is a sequential number of the CAN message. States: is the time stamp of the CAN message in CPU states. ID: is the CAN message identifier used for transmission or receiving Dir: is the direction of the CAN message: Xmit for transmit output of the CAN controller, Rec for receive incoming messages. Ch or MO: channel or message object number (depends on the device). Typical CAN Output Wave form: In this project we are using standard or base frame format. Following represents the piece of code of our project to enable standard or base frame format. Figure 8: CAN Output Waveforms As the figure shows, the CAN levels are represented in two states 1) low level (dominant) 2) high level (recessive). When the CAN bus is found free, it is indicated by recessive level. When node A transmits logic 0 & node B transmits logic 1 bits, it results in collision & lastly victory will be of dominant bit. It clears that high priority message is transmitted with less delay. The low priority messages should make attempts to resend for fixed clock cycles. In the above figure TX1, TX2 and RX1, RX2 shows the CAN A and B TX and RX. All the nodes connected to bus will check that the bit in bus is same as that of bit transmitted, if result is yes then the node will continue to transmit or else if both bits are different, the node will stop sending bits & begins to receive. IV.FUTURE IMPLEMENTATION The proposed co2 level monitoring system is scaled version of real time system, which is needed to be implemented in food & agro industry. It includes only monitoring system but not the controlling system. Number of CAN nodes can be implemented.gps & GSM modules can be used to transmit data to remote places. Along with co2 other parameters such as temperature, pressure & humidity can be All Rights Reserved 106

8 V. CONCLUSION Proposed work for the CAN Protocol Based Co2 Monitoring System is successfully implemented & experimental results show that, the CAN protocol is a new boost in industrial automation field other than automobile industry. The serial robust communication is achieved by defining the CAN object ID s. The co2 level is sensed by sensor nodes & sensed data is transmitted to master node further it is displayed on LCD. The proposed system gives notable accuracy in detecting & monitoring co2 level. REFERENCE 1. S.Neethirajan, D.S.Jayas, S.Sadistap, Carbon dioxide (co2) sensor for the Agri food industry A Review, Feed bioprocess Techno (2009). 2. Ubaid Saudagar, Implementation of CAN protocol for Industrial automation, IJSETR Wei Lun Ng, Chee Kyun Ng, Borhanuddin Mohd. Ali, Nor Kamariah Noordin, and Fakhrul Zaman Rokhani, Review of Researches in Controller Area NetworksEvolution and Applications. 4. Bosch, CAN Specifications, Robert Bosch Gmbh, Postfach, Han- Way Huang, PIC Microcontroller: An Introduction to Hardware and Software Interfacing,Thomsan Delmar Learning. 6. pratek patil, GSM Based Temprature Logger for CNC Machines Using CAN Bus.. 7. Hanwei Electronics Co Ltd MQ-7, Website http// 8. Microchip, MCP 2551:High Speed CAN Transceiver, Datasheet.. 9. keil Wikipedia website All Rights Reserved 107