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Introduction Today we are going to study GSM based Speed Control of Motor. This is a robot which can be controlled by using cell phone. Later on we can build application like controlling the electricity of a building with a cell phone using same development board. We are going to discuss ….
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Introduction • Today we are going to study GSM based Speed Control of Motor. This is a robot which can be controlled by using cell phone. • Later on we can build application like controlling the electricity of a building with a cell phone using same development board.
We are going to discuss …. • What is DTMF? • DTMF Keypad table • HT9170B IC • Application Circuit • Sample Code • How to control Speed of Motor using DTMF?
How to use it to control Motor You can use this system in robotics for controlling speed of Motor remotely. It can be considered as an infinitely long range remote control of your robot. Limitations Availability of network connectivity. Portability of errors id very high due to unreliability.
DTMF(Dual-Tone-Multiple-Frequency) • DTMF signaling is used for telecom signaling over analog telephone lines in the voice frequency band between telephone handsets and other communication devices and the switching centre. • In other words DTMF is a method of instructing switching system of the telephone numbers to be dialed, or to issue commands to switching systems.
Table Description • DTMF table is laid out in 4*4 matrix. • Row represents low frequency . • Column represents high frequency. • The multiple tones are the reason for calling the system multi frequency. • Tones are then decoded by switching centers to determine which keys are pressed.
DTMF Decoder/Receiver IC(HT9170B) • Operating voltage : 2.5V – 5.5V • Minimal external components • No external filter required • Excellent performance • 3.58 crystal or ceramic resonator • 18 pin package
Working of the IC • Tone is attached to 0.1 micro F capacitor on the top corner. • Mount the circuit on the robot with auto answer mode on. • Connect one wire of the headphone to the wire and other to the ground. • The tone is then passed to amplifier for filtering. • OE is the output enable pin, high on this pin will enable the output . • D0,D1,D2 and D3 are the decoded output of the IC. ……continued.
Working of the IC • DV is data valid pin, it’s a output pin, Set to high itself by IC when valid data is available on these bits. • RT/GT and EST are pins for setting effective time duration of tone to check for authenticity.
Connecting Cell phone to circuit • Connect the cell phone to circuit. • Call the cell phone from a remote phone • Now press the keys on the remote phone and you will see the LED’s blinking.
Advantage • Remote Control for long Distance • Simple Operation Far From Sight • Less Power Consumption
Applications • Robotics and Wireless Robotic Arm • Industries are using RF Solutions for monitoring , process, control, inventory tracking, data links and bar code reading devices. • Automotive companies employing RF for wireless Remote Control, Remote key less entry and safety applications . • Consumer products including electronic toys, door openers. • Manufacturing industries like plastic, textile, chemical etc.