Example: Enable sleep mode

Transcription

1 Example: Enable sleep mode In this example, you will learn how to extend the battery life of an XBee ZigBee module. The example uses all three modules included in the kit to demonstrate how a ZigBee network handles messages when some modules are sleeping. You will configure one of the modules as coordinator and the other two as end devices with different sleep modes. An end device will periodically send the value of an ADC to the other end device. Since the receiver will be asleep, the coordinator will store all of its messages and forward them to the destination module once it has woken up. If you get stuck, go to the Troubleshooting links at the end of the example. Steps

2 1. Requirements Connect the components Configure the XBees 4. Sleep 5. What have you learned? 6. Extend the example 7. Troubleshooting

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4 1. Requirements Three XBee ZigBee modules Three XBee Grove Development Boards Three micro USB cables One computer XCTU 6.0 or later Hardware Software For further information about XCTU, go to the XCTU walkthrough. Connect the components 1. Plug the XBee modules into the XBee Grove Development Boards and connect them to your computer using the micro USB cables provided. For further information on how to connect your hardware, go to the Assemble the hardware section. After connecting the modules to your computer, open XCTU. Make sure you are in Configuration working mode. Configure the XBees To transmit data wirelessly between your XBees, you must configure them to be in the same network. Remember that in the ZigBee protocol, one device must be the coordinator and the rest can be routers or end devices. In this case, you will have two end devices configured to sleep using different sleep modes: one with cyclic sleep (XBee B) and the other with pin hibernate sleep (XBee C). The coordinator is in charge of storing the messages sent from XBee B to XBee C while XBee C is asleep. It forwards the messages once it wakes up. 1. Restore the default settings of all XBees with the Load default firmware settings button at the top of the Radio Configuration section. Use XCTU to configure the following parameters: Param Effect XBee A XBee B XBee C ID Defines the network for a radio to attach to. This must be the same for all radios on your network. JV Enabled [1] Enabled [1] Verifies if a coordinator exists on the same channel to join the network or to leave if it cannot be found. CE Enabled [1] Sets the device as coordinator. DH 0013A200 Defines the destination address (high part) to transmit the data to.

5 DL SL of XBee C Defines the destination address (low part) to transmit the data to. Use the address to address the coordinator. NI COORD ED_CYCLIC ED_PIN Defines the node identifier, a human-friendly name for the module. The default NI value is a blank space. Make sure to delete the space when you change the value. AP API enabled [1] API enabled [1] API enabled [1] Enables API operating mode. SP Defines the duration of time spent sleeping. 384 (hexadecimal) = 900 (decimal) x 10 ms = 9 seconds. SM Cyclic sleep [4] Pin Hibernate [1] Enables cyclic sleep mode on XBee B and pin hibernate sleep mode on XBee C (both end devices). ST 7D0 Defines the period of inactivity (no serial or RF data received) before going to sleep. 7D0 (hexadecimal) = 2000 (decimal) x 1 ms = 2 seconds. SO 2 Keeps the module awake during the entire period. D2/D3 ADC [2] Sets the DIO2/AD2 or DIO3/AD3 pin as ADC in XBee B, depending on if the XBee module is THT or SMT. This pin is connected to a potentiometer. Configure the D2 parameter as ADC [2] only if XBee B is surface-mount (SMT). However, if XBee B is through-hole (THT), you have to configure the D3 par ameter as ADC [2] instead of the D IR 3E8 Configures XBee B to send an IO sample every second (1000 ms = 3E8 in hexadecimal). keep the default value. Write the settings of all XBees with the Write radio settings button at the top of the Radio Configuration section. 4. Sleep With this configuration, ED_CYCLIC sends the value of the potentiometer to ED_PIN every time it wakes up. The coordinator stores all the D_CYCLIC samples sent to ED_PIN until it wakes up. To verify, perform the following steps in XCTU: 1. Select ED_PIN module (receiver). Switch to Consoles working mode. Open the serial connection with the module. 4. To request the module to sleep, click the DTR radio button from the top of the console to deactivate it (notice that the CTS indicator is also deactivated):

6 The DTR pin is the same as the Sleep_RQ pin. When the DTR option is deactivated, the module goes to sleep; when DTR is activated, the module wakes up. 5. After 20 seconds or so, activate the DTR button: 6. Check that the module receives a series of IO Samples (IO Data Sample RX Indicator): When the module wakes up, it immediately receives several IO samples instead of receiving one every second ( parameter). IR This happens because the coordinator stores the samples that ED_PIN is not able to receive while it is asleep. Once ED_PIN wakes up, the coordinator sends all IO samples at once. 7. Select one frame and check its details in the right panel. You will see the value of the potentiometer (DIO3_AD3) and other details related to the frame Repeat step 4 and rotate the potentiometer of the board where ED_CYCLIC is attached. Wait for another 20 seconds and check that the new packets that arrive contain a different value for the DIO3_AD3 pin. If you leave the receiver module (ED_PIN) awake, ED_PIN receives an IO sample every second while the ED_CYCLIC is awake ( ST val ue is two seconds). After that, ED_CYCLIC goes to sleep for nine seconds ( SP parameter). Then the cycle starts over again.

7 Don't forget to close the serial connection with the module when you finish the example. 5. What have you learned? In this section, you have learned that: Modules with ZigBee protocol, as well as others, can go into a temporary sleep state in which they consume virtually no current. In ZigBee, only the modules configured as End Devices can go to sleep. When an end device is asleep its parent (the router or coordinator that allows the end device to join the network) buffers its data until a timeout expires ( SP), or until the end device sends a poll request to retrieve the data. Pins 9 and 13 are related to the sleep modes: you can use pin 9 to put the module to sleep, and pin 13 to determine the sleep state of the device. While an XBee is in sleep mode, there is no data transmission or reception. If you try to communicate with the module when it is asleep, XCTU displays a warning message saying that the module must be reset to wake up. To configure your module to go to sleep, you must configure the following parameters: Sleep Mode ( SM): Pin sleep mode (SM = 1) pull high pin 9 by connecting it to 3 volts to put the module to sleep. The module will wake up when pin 9 is de-asserted (low). Cyclic sleep modes (SM = 4 and SM = 5) enable the module to sleep and wake up on a fixed schedule. These modes need the ST and SP parameters to be configured. Time before Sleep ( ST) is the period of time during which no data is sent or received (while the module is awake) before returning to cyclic sleep. This parameter is only applicable for cyclic sleep modes. Cyclic Sleep Period ( SP) is the length of time an XBee remains asleep. This parameter is only applicable for cyclic sleep modes. 6. Extend the example If you're ready to move beyond this exercise and extend the example, try the following: Connect a battery to ED_CYCLIC (XBee B), ED_PIN (XBee C), or both and move the modules away from COORD (XBee A). Combine this feature with a real sensor to create a low-power sensor network. 7. Troubleshooting If you are encountering problems, these suggestions may help:

8 General How do I find the serial port of my module? You can remove the XBee Grove Development Board from the USB port and see which port name disappears from your port list. The name that disappears is your XBee board. Many people figure out which port is right via trial and error, but you can also use XCTU to find it: 1. Open XCTU and discover the radio modules attached to your computer by clicking 4. on the top-left corner. Select all ports to be scanned. Click Next and then Finish. Once the discovery process has finished, a new window notifies you how many devices have been found and their details. The serial port and the baud rate are shown in the Port label. An error saying that the port is already in use by other applications is displayed. The serial port where the local XBee module is connected can only be in use by one application. Check that the connection with the module in the XCTU console is closed and there are no other applications using the port. The error 'Device driver software was not successfully installed' is displayed. Sometimes when you connect the XBee Grove Development Board into you computer, the operating system cannot install the driver automatically. If you get that error, try to remove and re-insert the board into your computer. If the OS is still unable to install the driver, remove and re-insert the board into another USB port. As a last resort, install manually the USB drivers following the instructions that appear in the step 4 of the Downloading and installing XCTU section. How can I physically identify the XBee modules? Once you have added the modules to XCTU, a simple way to identify them is to read the radio settings of each one and check the Rx and Tx LEDs of the XBee Grove Development Boards. These LEDs indicate that the XBee module is receiving (Rx) or transmitting (Tx) information through the serial port. When you read or write the settings of a module, its Rx and Tx LEDs blink, so you can identify which module is connected to each serial port.

9 An error is reported when installing XCTU. XCTU requires Administrator permissions XCTU Check that you have Administrator access on the machine where you are installing XCTU. On Windows systems, a User Account Control dialog may appear when you install XCTU or try to run the XCTU program. You must answer yes when prompted to allow the program to make changes to your computer, or XCTU will not work correctly. Note that you may also need to talk to your network manager to gain permission to install or run applications as administrator. No radios are found when discovery is performed or no serial ports are listed. Check cables Double check all cables. The USB cable should be firmly and fully attached to both the computer and the XBee Grove Development Board. When attached correctly, the association LED on the adapter will be lit. Check that the XBee is fully seated in the XBee Grove Development Board When the XBee is correctly installed, it should be pushed fully into the board and no air or metal should be visible between the plastic of the adapter socket and the XBee headers. Also, double check that all ten pins on each side of the XBee made it into a matching hole in the socket. Check the XBee orientation The angled "nose" of the XBee should match the lines on the silk screening of the board and point away from the USB socket on the XBee Grove Development Board. Check driver installation Drivers are installed the first time the XBee Grove Development Board is plugged in. If this process is not complete or has failed, try the following steps: Remove and re-insert the board into your computer. This may cause driver installation to re-occur. Remove and re-insert the board into another USB port. (Windows) Open Computer management, find the failing device in the Device Manager section and remove it. You can download drivers for all major operating systems from FTDI for manual installation. Check if the modules are sleeping The On/Sleep LED of the XBee Grove Development Board indicates if the module is awake (LED on) or asleep (LED off). When a module is sleeping, it cannot be discovered in XCTU, so press the Commissioning button and will wake up for 30 seconds. After resetting an XBee to factory defaults, XCTU reports errors for the KY and DD settings. This is a known issue with the versions of XCTU or less. When the Invalid settings dialog appears, it is safe to continue to write settings. AES Encryption Key (KY) is a setting that must be set by the user when encryption is used and does not apply with factory settings. Device Type Identifier (DD) is a diagnostic parameter which is not used in the operation of the radio and can safely be set to any value. Enable sleep mode example ED_PIN does not receive any message. Ensure that the module is joined to the network. To verify this, check that the Associate LED of ED_PIN is blinking when the DTR button is activated. If not, reset the module and wait a few seconds.