Understanding Using XBee Pro

Transcription

1 Fall 2013 Department of Engineering Science ZigBee Lab Understanding Using XBee Pro Notes to Students: Each student must turn in a separate report. The lab section can be done in groups of TWO. You must specify the name of your Lab partner on your individual report. Please try to reduce the size of plots and tables to avoid wasting papers. Double- sided reports are welcomed Time of Completion: Estimated time to complete the measurements is about 1-2 hours. Please note that you may have to go back again to redo some of the measurements. DONOT wait until the last day Important: All the connectors are provided in the lab. In some cases you have to search for the right connector for the setup. Please make sure all laboratory components are returned back to the testing table. Please keep the lab clean Make sure you sign the signup sheet Please be Gentle with the connectors All FIGURES must have Figure Number and Caption Figures without these will not be acceptable Part required for the lab: 1. XBee on Breakout Board - USB Interface 2. Serial Interface 3. Loopback Connector 4. Wi- Spy 5. XBee Evaluation Board 6. Power adaptor for the Eval Board You can complete the lab using your own laptop. In this case you need the following software: X- CTU - Download here. Read the tutorial. Chanalyzer CoolTerm (or any serial port terminal application): Objectives: The purpose of this lab is to understand basics of Radio using XBee Series 1 modules under MaxStream brand, made by Digi. Currently, all new XBees are being sold under Digi brand. You will be establishing a Point- to- Point connection using two XBee modules. The XBee modules can be con]igured using X- CTU software directly. AT (ATtention) Commands are instructions are used to control a modem. In this lab you also learn how to dissect the transmitted frame from XBee and parse the data. Using range test, you will examine radio range of XBee Pro. You are also required to examine the free- space path loss for XBee Pro radio signal. XBee contains multiple on- chip analog and digital ports. We will examine how these ports can be enabled. Note that in this exercise we do not have any router or coordinator. Furthermore, you will learn about physical layer characteristics of IEEE standard, including its frequency bands, 3- db bandwidth, Power Spectral Density (PSD), etc. using a spectrum analyzer (Wi- Spy). In the second part of the lab we will be using LabVIEW to interact with XBee frames. F.Farahmand Page 1/ 10 Updated: Monday, December 1, 2014

2 Fall 2013 Department of Engineering Science ZigBee Lab Pre- lab: Before you start the lab make sure you understand the different between Series 2 and Series 1 XBee. Read this to learn more. Read about addressing modes used in Make sure you realize the difference between XBee Pro and XBee. Read this to learn more. Please review the following links: 1. X- CTU Tutorial 2. Setting up the connections: 3. Performing Range Test: ftp://ftp1.digi.com/support/documentation/ _a.pdf 4. More accessories on XBEE: 5. Access XBEE Manual 6. Basic connection between two XBEEs 7. Review the Eval Board schematic Notes: You can do the lab in a group with one other student. You need to select your own lab partner. Please make sure you sign the signup sheet. Each TEAM must submit a separate report No more than two people per team is allowed Include the name of both participants. Please only answer the numbered questions (A.1, A.2, etc.) Please be very gentle with the RF devices and lab setup. Handle devices carefully Be very careful as you remove connectors and devices. Please do not remove anything from the lab. If somehow you cannot Read XBEE registers, always make sure the battery is good Always check the baud rate if the communication link is not working. F.Farahmand Page 2/ 10 Updated: Monday, December 1, 2014

3 Fall 2013 Department of Engineering Science ZigBee Lab BASIC SETUP Perform the following steps: A- In this section you are required to create a point- to- point link between two XBees. Assume the PAN has an ID of 2001 and the operating channel is 12. You should read about Channel (CH) register (Read Chapter 3 ed.co.uk/docs/xbe001.pdf). Connect the SMALL XBee on the breakout board, as shown below, to PC s USB. We refer to this as the Xbee Transmitter. Connect the Eval Board to the Serial Cable. We refer to this as the Remote Xbee Receiver. Invoke the X- CTU software. Make sure you can connect to both XBees. B- A%er invoking X- CTU program, make sure you go to PC Se'ngs tab and select the proper interface. Click on Test BuAon to make sure you are connected to the device. C- Go to Modem ConfiguraEon tab and click on Restore. You should get something like the figure shown here. Obtain a screen snapshot for BOTH the receiver and transmiaer modules. IdenEfy which COM port RX and TX module is connected to. You will not receive any grade if you are missing these snapshots. D- Answer the following queseons: 1. What are the serial numbers (H/L) of the transmiaer and the receiver modules? This is also on the back of XBee chip. Please handle the modules with care 2. What version of firmware has been loaded in the device? 3. What is the PAN number? F.Farahmand Page 3/ 10 Updated: Monday, December 1, 2014

4 Fall 2013 Department of Engineering Science ZigBee Lab Using the Serial Numbers of the Transmitter and Receiver, properly setup the TX Bee and RX XBee. Note: Read the lecture slides about addressing to properly setup the addressing. Assume the PAN has an ID of 2001 and the operating channel is 12. You should read about Channel (CH) register (Read Chapter 3 ed.co.uk/docs/xbe001.pdf). Connect the LOOP BACK connector (RED DB- 9 shown below) to the RX module. Connect the TX module directly to the PC. Power up the RX module. Note that the remote module (or RX module) refers to the evaluation board and the TX module refers to the base station connected to the PC. The ]igure below shows the high- level hardware con]iguration for this experiment: 1. Click on the Terminal tab. Make sure the link is properly operating by sending an ASCII character and receiving it. Click on Assemble Packets button. Type your name in there and send the data. Note that you should see the transmitted characters (your name) and the received characters. (a) Using a table list all the addressing information for TX and RX modules: Sources, Destination, PAN, MY. (b) Show a print screen of your results. (a) If you remove the Loopback what happens? Explain why? (b) Which pins on the XBee are looped back? Refer to the schematic of the evaluation board. How can you replace the red DB- 9 Connector with a single wire? Show the schematic. 2. Perform the Range Test. Do you get any errors? What is the received signal level? NOTE: If everything is operating as expected, you can SAVE your setups by going to the Modem Con]iguration tab and clicking on SAVE. You can LOAD this con]iguration later. 2. Change the PAN ID in the TX module (only) to Run the Range Test again. What happens? Explain. USB Power Supply 5VGND Din VCC 5V GND Xbee Base Dout Xbee Remote F.Farahmand Page 4/ 10 Updated: Monday, December 1, 2014

5 Fall 2013 Department of Engineering Science ZigBee Lab 3. Change the MY of the TX module (only) to Run the Range Test again. What happens? What does MY indicate in XBee Radio? 4. Read the Channel (CH) register on the TX module. Change the channel to a different valid value (Read Chapter 3 ed.co.uk/docs/xbe001.pdf). Perform the Range Test. Check the CH on the RX module and make sure it is different from CH on the TX module. Explain what is happening. 5. What is RSSI used for? What does it represent? What happens to it if you move the RX module to a different location far from the base station? 6. Create a table and list the distance (in meter) and the RSSI values as the RX module moves away from the TX module. Plot the distance (meter) vs. power received at the base station in db/dbm. You should have at least 5 points in your plot. 7. Plot the theoretical power loss (in db) for XBee as of distance. Compare this with your results above. Show both plots on the same Jigure. All values must be expressed in db/dbm. 8. Referring to the Modem Con]iguration tab, which register deals with power level of the radio? Change it and see how the transmit power changes. Explain your observations. Create a table and for each transmit power level measure the received RSSI value. To perform this test set the register on the transmitter module and read the RSSI value on the receiver XBee. F.Farahmand Page 5/ 10 Updated: Monday, December 1, 2014

6 Fall 2013 Department of Engineering Science ZigBee Lab USING AT COMMANDS In the following steps we learn how to use AT commands. AT commands are designed for more direct human interaction. Below is a simple example showing how AT commands work: Note that after +++ you should wait to get OK; DONOT press ENTER Example: -> +++ (get into AT mode (Note 1)) <- OK -> AT (check if xbee modem is responding) <- OK -> ATBD (get current baud rate as above) <- 3 (9600) -> ATBD 4 (set baud rate to 19200) <- OK -> ATBD (check again) <- 4 -> ATWR (write the baud rate change to flash) <- OK what will be the command to change power level of the TX? 1. What is the command to change the baud rate to ? Note that if you change the BR you need to recon]igure the XBee s baud rate in the Port Settings tab in order to be able to communicate with the XBee. 2. Using AT, change the PAN ID of the TX to 2000 and read it back. Show a snapshot of your result. F.Farahmand Page 6/ 10 Updated: Monday, December 1, 2014

7 Fall 2013 Department of Engineering Science ZigBee Lab TESTING WITH THE SPECTRUM ANALYZER SOFTWARE Connect the Wi- Spy 2.4x to the PC (it is probably already connected) and run the Chanalyzer 4 software. Read about Chanalyzer and watch a short video here: products/wi- spy/. Here are some examples 1: 1. Turn off the XBee modules. Take a snapshot of all 2.4G band frequencies that are detected in the lab. 2. Turn on XBee modules and ]ind your XBee signal using the ZigBee signal template. Take a snapshot. You may have to wait for a few minutes for a good reading. Make sure your snapshot is readable, otherwise you will not receive a grade. 3. Change the channel on your PAN ID (on both TX and RX). Run the Range Test. Make sure everything is operating properly and ]ind your ZigBee signal using the ZigBee signal template. Take a snapshot. 4. What is the difference between the ZigBee and WiFi signals in the way they appear? 5. Use spectrum analyzer (Chanalyzer) and answer the following: a. Find the 3dB bandwidth. Print a snapshot of the PSD. You may want to perform this test for a while to obtain a good signal pattern. b. Can you determine the null- to- null bandwidth. What is it? c. What happens if you attach an antenna to the TX module? How much the received power is changed? d. Using the Cantenna generate an interfering signal. Take a snapshot of the interfering signal. e. Start running the Test Range. Do you get any errors? Does the working channel on XBee change? CAPTURING DATA FROM THE REMOTE DEVICE Make sure you can perform the Range Test between the remote device and the Base Station to ensure your connectivity between the devices. Modify the Remote module as follow 2 : Change the I/O port 0, 2, and 3 to be DI (Digital Input) Set the Sample Rate to 80 milliseconds. Set the number of Sample Before Transmission to 1. Connect the TX module to the computer. At this point, the Red LED on the Remote module should be blinking. Also, you should see that the LED on the TX module should be (barely) blinking. Note that there is no need to have the Loopback connector. Include a snapshot indicating the new values. 1 hap:// 4/?utm_campaign=So%ware&utm_medium=Chanalyzer. 4&utm_source=HelpMenu Make sure you review the Manual: hap:// 2 XBee- Manual.pdf F.Farahmand Page 7/ 10 Updated: Monday, December 1, 2014

8 Fall 2013 Department of Engineering Science ZigBee Lab Open the X- CTU program. Make sure you can communicate with the RX module. Go to Terminal tab. You should see something like the ]igure below. These are the packet frames the Coordinator module is receiving. Read the manual. Explain clearly, where each packet frame starts. How many bytes are in each packet? Which part of the packet contains the analog data from I/O ports? Take a snapshot of your own data and mark one frame on your ]igure. Show the part that contains the data from I/O ports. Which byte indicates the RSSI level? Show it on your snapshot. Do you see the same patterns being repeated or each frame is different? Are the pull- up resistors enabled in your setup? How do you know? Which register indicates that? What is the value of the register? F.Farahmand Page 8/ 10 Updated: Monday, December 1, 2014

9 Fall 2013 Department of Engineering Science ZigBee Lab CAPTURING DATA FROM THE REMOTE DEVICE USING LBVIEW A- Setup the receiver such that AD1 and AD2 are enabled as digital input. Set the baud rate to Set the Sample Rate to 1000 milliseconds. Set the number of Sample Before Transmission to 1. Connect the TX module to the computer. Power up the the remote XBee. Using the evaluation board s schematic determine which switches on the remote module are connected to AD1 and AD2 ports. Use the provided sample LabVIEW program in the folder 3 and read the received data from the remote module. You need to understand how the received API frame is constructed. Refer to XBee manual for more information. Your program should be something like below. You can use this help sheet (many thanks to Richeee for creating it). To learn more about LabVIEW Programing check this web site. Your program must have the following features: 1. When the switches are closed the LabVIEW s Green Buttons on the front panel of your VI must be enabled, otherwise they should be disabled. 2. Plot the RSSI value on a graph on the front panel VI. 3. Modify the LabVIEW VI such that you extract the following values from the received packet. 4. You need to demonstrate that the program is fully functional. 3 If you are observing any VISTA problem while opening the LabVIEW program, you may want to restart your computer. We have tested the program on Windows 7 and XP and there should be no problem. F.Farahmand Page 9/ 10 Updated: Monday, December 1, 2014

10 Fall 2013 Department of Engineering Science ZigBee Lab Review Questions: By the end of this lab you should be able to answer the following questions (DO NOT submit this part): 1. What does MY indicate? How is it different from PAN ID? 2. What is the unit of RSSI? Can you change RSSI value on a XBee chip? 3. What does it mean if the value of RSSI register is set to 40? 4. What is the minimum setup required to get two XBEEs to communicate with one another? 5. Explain exactly how we can use two XBees to measure the temperature and report it to a computer (you know include the hardware schematic and software setup for each device). 6. In the question above what are the possible things we can do to reduce the power consumption on the remote device? 7. Assuming the transmitted XBee power is 10 mw centered at MHz with a 3- db bandwidth of 2MHz, draw the PSD for the signal. 8. What is the point of setting the Baud Rate in XBee. Is it possible to get two XBee chips with different baud rates to communicate with one another? 9. What does it mean when we perform a loopback test between two XBee chips? 10. What is the main difference between regular ZigBee and ZigBee pro? 11. How many ZigBee channels are available in 2.5 Band? 12. Which register do you set to change the transmit power? What is the maximum transmit power in mw? 13. Can you change the parity setting in RF module? How? F.Farahmand Page 10/ 10 Updated: Monday, December 1, 2014