The EFR32 Sleepy applications demonstrates Sleepy End Device behaviour using the EFR32's low power EM2 mode. The steps below will take you through the process of building and running the demo
For setting up the build environment refer to examples/platforms/efr32mg12/README.md.
$ cd <path-to-openthread> $ ./bootstrap $ make -f examples/Makefile-efr32mg12 COMMISSIONER=1 JOINER=1 DHCP6_CLIENT=1 DHCP6_SERVER=1 BOARD=BRD4161A
Convert the resulting executables into S-Record format and append a s37 suffix.
$ cd output/efr32mg12/bin $ arm-none-eabi-objcopy -O srec sleepy-demo-mtd sleepy-demo-mtd.s37 $ arm-none-eabi-objcopy -O srec sleepy-demo-ftd sleepy-demo-ftd.s37
In Silicon Labs Simplicity Studio flash one device with the sleepy-demo-mtd.s37 image and the other device with the sleepy-demo-ftd.s37 image.
For instructions on flashing firmware see examples/platforms/efr32mg12/README.md
For demonstration purposes the network settings are hardcoded within the source files. The devices start Thread and form a network within a few seconds of powering on. In a real-life application the devices should implement and go through a commissioning process to create a network and add devices.
When the sleepy-demo-ftd device is started in the CLI the user shall see:
sleepy-demo-ftd started sleepy-demo-ftd changed to leader
When the sleepy-demo-mtd device starts it joins the preconfigured Thread network before disabling Rx-On-Idle to become a Sleepy-End-Device.
Use the command “child table” in the FTD console and observe the R flag of the child is 0.
> child table | ID | RLOC16 | Timeout | Age | LQ In | C_VN |R|S|D|N| Extended MAC | +-----+--------+------------+------------+-------+------+-+-+-+-+------------------+ | 1 | 0x8401 | 240 | 3 | 3 | 3 |0|1|0|0| 8e8582dbd78c243c | Done
Pressing button 0 on the MTD toggles between operating as a Minimal End Device (MED) and a Sleepy End Device (SED) with the RX off when idle.
Pressing button 1 on the MTD sends a multicast UDP message containing the string “mtd button”. The FTD listens on the multicast address and will toggle LED 0 and display a message in the CLI showing “Message Received: mtd button”.
Pressing either button 0 or 1 on the FTD will send a UDP message to the FTD containing the string “ftd button”. The MTD must first send a multicast message by pressing the MTD's button 1 so that the FTD knows the address of the MTD to send messages to.
This will toggle the state of LED0 on the MTD. If the MTD is operating as a sleepy end device then the MTD polls the parent every 5 seconds for messages and will update the LED state on the next poll.
Open the Energy Profiler within Silicon Labs Simplicity Studio. Within the Quick Access menu select Start Energy Capture... and select the MTD device. When operating as a Sleepy End Device with no LEDs on the current should be under 20 microamps with occassional spikes during waking and polling the parent. With the LED on the MTD has a current consumption of approximately 1mA.
When operating as a Minial End Device with the Rx on Idle observe that the current is in the order of 10ma.
With further configuration of GPIOs and peripherals it is possible to reduce the sleepy current consumption further.
To allow the EFR32 to enter sleepy mode the application must register a callback with efr32SetSleepCallback. The return value of callback is used to indicate that the application has no further work to do and that it is safe to go into a low power mode. The callback is called with interrupts disabled so should do the minimum required to check if it can sleep.