An Ultra Low Powered Msp430 Microcontroller Based Control System for a Composting Process

An Ultra Low Powered Msp430 Microcontroller Based Control System for a Composting Process

A.Prasanna Lakshmi K.Vijayachandra

M.Tech(Student) Assoc Prof

PKSK College PKSK College

ECE Dept ECE Dept

Abstract:

Composting is a process by which organic material such as scraps, garbage, wood shavings, cardboard, and paper is biodegraded by microorganisms, resulting in the production of organic and/or inorganic by-products and energy in the form of heat. Microorganisms that are present in organic waste materials, start the decomposition process when they get exposed to air, and the moisture content of the waste is brought to a suitable level; carbon dioxide, water and heat are given off. The temperature of the heap rises as the degradation process speeds up, which normally occurs slowly in organic waste. To keep the temperature and moisture to a suitable level through air flow to make organic composting process properly. To achieve this work we designed an intelligent remote monitoring and control system controller for a composting process using Texas

Instruments ultra low powered MSP430 microcontroller chip, wireless module for establishing a RF link between the two MSP430 microcontrollers, one is transmitter and another is receiver which is also works as controller. Composting is the best economical and sustainable method for promoting organic farming. Our work is a major step in developing a low cost and efficient control system for a compost manufacturing process which can be used by farmers to produce rich content, nutrient fertilizer. This same system we can use in cold storages to maintain cooling. We also designed the system using GPRS module inplace of Xbee communication to transmit composite parameters to remote monitoring system.

Categories and Subject Descriptors

C.3 [Special-Purpose and Application- Based Systems]: Microprocessor/microcomputer applications, Real time and embedded systems, process control.

General Terms:Measurement, Design, Experimentation, Verification.

Keywords :Microcontroller, composting, transmitter, receiver

INTRODUCTION

Composting is a process by which organic material such as yard trimmings, kitchen scraps, wood shavings, cardboard, and paper is biodegraded by microorganisms, resulting in the production of organic and/or inorganic by-products and energy in the form of heat. Microorganisms that are normally present in organic waste materials, start the decomposition process when they are exposed to air, and the moisture content of the waste is brought to a suitable level; carbon dioxide, water and heat are given off. As a result the temperature of the heap rises thereby speeding up the basic degradation process, which normally occurs slowly in organic waste. The final product is a compost which is of significant value in

agriculture. Moreover for the process to give significantly good quality compost the process parameters have to be properly monitored and adjusted .Two such parameters that are important and interdependent to some extent are temperature and oxygen content of the waste material[8]. So a control system is designed to control temperature of the composting process and air flow rate (oxygen supply).

CONTROLSYSTEMDESIGN

Control system is designed around a Texas Instruments ultra low powered MSP430F1232microcontroller,CYWM69

35 wireless module for transmitting compost temperature to a remote monitoring station. Figure 1 shows the control scheme along with the compost reactor

Figure1.CompostControllerandTransmitter

Compost reactor consists of a drum that is insulated within an outer drum to prevent heat loss during the composting process. In the center of the inner drum, a resistance temperature detector(RTD)

,installed vertically, senses the temperature of the compost. A perforated plate, located approximately 5 inches above the bottom of the reactor, suspends the compost over the air inlet and provides even air distribution to the compost. Air flow to the compost is provided by the blower/fan. The fan offers a very easy means to introduce air(oxygen) in the reactor at regular intervals, and to circulate an air current to cool the process when required. There are basically two conditions for the fan to be switched on; whether the recorded temperature is above 55 degree C, and at regular intervals of 20 minutes . In the first case the fan remains on as long as temperature does not fall below 55 degree C. In the second case the fan is switched on for approximately 30 seconds to allow an influx of oxygen required for the composting process. This amount of time is sufficient to allow enough oxygen in the plant for the process to be sustained [8].The moisturecontent of the compost mixture is adjusted by adding water to the compost reactors through the top sample ports.

SignalConditioningandTransmitter

This application uses PT100 RTD for temperature sensing. The RTD signal conditioning circuit converts the resistance changes on account of temperature variations into a proportional voltage that is applied to analog to digital converter. The MSP430F1232 device integrate,10-bit

200 ksps ADC with internal reference, sample and hold and data transfer controller. Also the USART configured in SPI mode is used to communicate with the CYWM6935 (2.4GHz ISM band)wireless module. The MSP430F1232 microcontroller acts as a SPI master while CYWM6935 wireless module acts as SPI slave. The acquired temperature information is processed according to the control logic , displayed locally on the LCD screen and simultaneously transmitted over the air using CYWM6935 module. Depending upon the time elapsed and temperature value the fan is switched on and off according to the logic depicted in the flowcharts.The fan aerates and cools the compost in a reactor. The bacteria in the material require a minimum level of oxygen for their metabolic processes; they generate significant amounts of heat as they digest the compost. If left uncontrolled, they

might use up all the oxygen or the temperature might rise to a level that would kill the bacteria.

RemoteMonitoringStation(Receiv er)

The remote monitoring station as shown in Figure 2 consists of MSP430F1232 microcontroller at it's heart,CYWM6935 wireless module and LCD display for remote monitoring of the compost temperature. The remote monitoring station can be placed at a centralized location to monitor the progress of the composting process. The CYWM6935 provides a complete SPI-to-antenna radio modem. The CYWM6935 is designed to implement wireless devices operating in the worldwide 2.4-GHz Industrial, Scientific, and Medical (ISM) frequency band (2.4 GHz to 2.4835 GHz)supporting a range of 50 meters or more. This restricts us to place remote monitoring station within 50 meters of the transmitter. A Texas Instruments MSP430 Family microcontroller(MSP430F1232) has been chosen to use for the application because it is readily available, well supported with documentation and applications information , and has relatively inexpensive evaluation tools. The family of microcontrollers is designed

specifically for industrial control, instrumentation, and measurement tasks with low-power, extended battery-life applications as prime design objectives[2][4]. Rather, the easy-to- understand architecture, instruction set, and family structure contributed significantly to the selection.

Figure 2. Remote Monitoring Station

Flowcharts

Figure 3. Transmitter Flowchart

Figure 4. Receiver Flowchart

The software for this application is developed in C language usng the IAR Embedded Workbench IDE which contains MSP430 IAR C Compiler,MSP430 IAR assembler, a powerful editor, project manager and Flash Emulation Tool (FET) debugger. The complete development system comprising a PC with the IAR Embedded Workbench installed, Olimex FET connected to the PC parallel port, JTAG and target board are shown in Figure 5 .

Figure 5. Software Development System

SOLAR POWERED AND BATTERY OPERATED SYSTEM

The entire electronics for this system is battery operated and solar powered. Solar panels charge the batteries. Power supply for the electronics uses low dropout regulators (LDOs) while the fan is driven by an inverter. So a solar powered control system for a environment friendly composting process makes this a truly green technology.

CONCLUSION

A control system for turning organic waste into a valuableproduct is presented in this paper. Usage of advanced microcontroller like Texas Instruments MSP430 makes the electronics reliable and ultra low powered. Composting reduces difficulty in treating organic waste and creates economic revenue stream from the sale of compost. It is a good source of fertilizer to the agricultural community for crop application. Applying a process control system ensures a product with consistent quality.

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