RIOT example app to collect temperature readings and report them via CoAP. Uses a JC-42.4 compliant temperature sensor via RIOT's SAUL sensor/actuator API. Uses the CoAP Observe exension to report the data with RIOT's gcoap implementation.
The sections below help to set up the data collector, including networking, the server that listens for the temperature readings, and sensor hardware to collect the readings.
Below are subsections for the supported networking types. The uppercase names below are variables in the make files.
| Name | Description |
|---|---|
| DATAHEAD_ADDR | Address of listening server |
| DATAHEAD_PORT | CoAP port for listening server |
Supports a board connected via serial interface. Build with the SLIP-specific make file, Makefile.slip:
make -f Makefile.slip BOARD="samr21-xpro"
See the RIOT border router example documentation for setup and use of SLIP. Verify addresses for the SLIP interfaces in the make file.
| Name | Description |
|---|---|
| SLIP_ADDR | Address of RIOT gateway |
| SLIP_PEER_ADDR | Address of connected host, for example a Linux laptop |
| BORDER_IF | Serial network interface number |
On my system, I test with the tun networking setup below.
$ cd ~/dev/riot/repo/dist/tools/tunslip/
$ sudo ./tunslip6 -s ttyUSB0 -t tun0 bbbb::1/64
The setup above must be run before the data collector tries to use the network. The data collector waits 20 seconds after it boots before attempting to use the network.
Supports a board connected wirelessly via the RPL routing protocol. Requires a second gateway router to forward traffic to the data server. Build with the standard Makefile:
make BOARD="samr21-xpro" NET_ROUTER=1
To run this configuration, be sure to set up the gateway router first, including establishing it as RPL root. Also, be sure the values below are defined as expected in the make file.
| Name | Description |
|---|---|
| HOST_ADDR | Address of host |
| ROUTER_IF | Network interface number |
By default, uses aaaa as the prefix for the RPL interface on the host and gateway. See the RIOT RPL tutorial for more information about use of RPL. See the gcoap SLIP example documentation for gateway router setup with RPL.
You should see output like below when starting a data collector.
$ make term BOARD="samr21-xpro" PORT="/dev/ttyACM1"
pyterm -p "/dev/ttyACM1" -b "115200"
2017-05-15 05:50:49,250 - INFO # Connect to serial port /dev/ttyACM1
Welcome to pyterm!
Type '/exit' to exit.
2017-05-15 05:51:05,028 - INFO # Initialized router address
2017-05-15 05:51:05,031 - INFO # Initialized RPL; pause 10 sec.
2017-05-15 05:51:15,045 - INFO # Initialized router RPL networking
2017-05-15 05:51:15,048 - INFO # Sending hello message to datahead
2017-05-15 05:51:15,051 - INFO # temperature: 19.37 C
2017-05-15 05:51:15,071 - INFO # 'hello' response OK
2017-05-15 05:51:35,074 - INFO # temperature: 19.37 C
2017-05-15 05:51:55,097 - INFO # temperature: 19.43 C
This implementation is designed only to test use of CoAP. RIOT does not support use of a physical sensor in this configuration.
Build with the standard Makefile. Follow the setup instructions for the gnrc_networking example. On my system, I test with the tap networking setup below.
$ sudo ip tuntap add tap0 mode tap user kbee
$ sudo ip link set tap0 up
# Data collector sends to DATAHEAD_ADDR in Makefile.
# Must define this address.
$ sudo ip address add fe80::bbbb:1/64 dev tap0
The RIOT data collector expects to communicate with a CoAP listener interested in the data. The interface between them includes these resources:
| Resource | Location | Description |
|---|---|---|
| /dh/lo | Listener | "Hello", registers RIOT host with listener (POST) |
| /dh/tmp | Host | Listener observes this resource on RIOT host (GET) |
I use Datahead to provide the server side of the interface.
We connect the Adafruit MCP9808 breakout board to a SAMR21 Xplained Pro board via I2C. The pins are:
| Function | SAMR21 | MCP9808 |
|---|---|---|
| I2C SCL | PA17 | SCL |
| I2C SDA | PA16 | SDA |
| 3.3V | VCC | Vdd |
| Ground | GND | Gnd |