Experiment 5.B. Multifunction Wireless Control. ECEN 2270 Electronics Design Laboratory 1

Transcription

1 .B Multifunction Wireless Control Electronics Design Laboratory 1

2 Procedures 5.B.0 5.B.1 5.B.2 5.B.3 5.B.4 Turn in your pre-lab before doing anything else. Check that Part A is in working order Wirelessly controlled LED Transmission t on Measurement Robot Control Electronics Design Laboratory 2

3 B.1 Check that Part A is in working order After completing part A you should have A solid understanding of how each of the blocks in your wireless communication receiver and transmitter work A working receiver with an experimentally verified center frequency within 10Hz of your nominal center frequency A filter gain of 0dB or less at both +40Hz and -40Hz from your nominal center frequency A peak-detector and comparator circuit that is working and tested A transmitter circuit with a tunable modulation frequency If you don t have all of these things go finish them! In Part B you will Connect your receiver to your Arduino Use your new wireless communication circuits as a remote control for your robot Electronics Design Laboratory 3

4 B.2 Wireless LED Control Connect the output of your wireless receiver circuit to your Arduino Wireless Receiver Circuit Receiver GND Signal Processing 5VDC Write test code to turn on the Arduino LED when you are transmitting, and turn it off when you are not Have a TA or Instructor check that this is working Include your code in your lab report Electronics Design Laboratory 4

5 B.3 Transmission t on Measurement We will be using pulse length to control your robot. This is one of the simplest ways to communicate using 1 s and 0 s, but it doesn t give you much flexibility. It is a good first step. For this method of control Your transmitter input will be a string of pulses at a fixed frequency with a certain t ON Your receiver will filter and re-digitize these pulses and output them to your Arduino The Arduino will measure the t ON of the incoming pulses, and take action based on the length. Fixed Frequency Input 5VDC Transmitter Circuitry Variable t ON 5VDC Receiver Circuitry Hey! Listen! The received t ON is between X seconds and Y seconds! That means I should preform action Z! Seconds Electronics Design Laboratory 5

6 B.3 Transmission t on Measurement Determine your fixed frequency input waveform characteristics t ON must be greater than 10/f m Why is this? Explain in your lab report. A good target for the minimum t ON is 20/f m Your input waveform should have a duty cycle D of no less than 15% and no more than 75% In your lab report describe your input waveform Frequency, minimum duty cycle D min, maximum duty cycle D max, minimum t ON, maximum t ON, etc Electronics Design Laboratory 6

7 B.3 Transmission t on Measurement Program your Adruino to measure the length of an input pulse and print it out to the serial port Using the pulsein() function is the easiest way to do this Include this code in your report, and a description of what you did, how you did it, and why. How does the pulsein() function work? If you could not program this function yourself ask! Generate a plot if input t ON vs. measured pulse length. You are likely to see that your measured pulse length is less than your set input t ON Why is this? Include the plot and an explanation in your lab report. Split your possible pulse lengths into 4 bins, and have your Arduino print a unique string for each See the example table to the right Pulse Length Bin You will have different timings and different bins than this 0ms < t ON < 10ms STOP table shows! Do not try and 10ms < t just use this table! ON < 20ms FORWARD Have a TA or instructor check that 20ms < t ON < 30ms LEFT this is working 30ms < t ON RIGHT Electronics Design Laboratory 7

8 B.4 Robot Control Write four Arduino functions stop() forward() left() right() Program your arduino to execute these functions based on the input pulses. You should be able to drive your robot around the lab this is what you will do for your demo! Electronics Design Laboratory 8