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Contiki REST/CoAP Quickstart using Econotags
Contiki has an implementation of the IETF CORE (Constrained RESTful Environments) working group's CoAP layer (Constrained Application Protocol). CoAP is a RESTful application layer that uses HTTP-like methods (GET, POST, PUT, DELETE) to interact with constrained networks. CoAP operates over UDP and supports reliable transmission.
This tutorial will show you how to run Contiki's CoAP demo on Redwire Econotags using an RPL border-router.
- Run a RPL border-router and tunnel
See the RPL HOWTO for details about running a RPL border-router.
- Build and run the
rest-server-exampleon a second Econotag
The following must be done on the contiki-mc1322x.git tree
git clone git://git.devl.org/git/malvira/contiki-mc1322x.git
Contiki CVS is currently down and the new SCM system hasn't been set up yet. The necessary changes will be pushed as soon as the new SCM is available. - 6 Februrary 2011
To build the rest-server-example:
cd contiki-mc1322x/examples/rest-example make TARGET=redbee-econotag
This will produce the binary image
rest-server-example_redbee-econotag.bin, which you can load directly
on to an mc1322x and execute.
mc1322x-load.pl -f rest-server-example_redbee-econotag.bin -t /dev/ttyUSB3
Then press the reset button to connect to the bootloader.
In this example, we are loading the CoAP server on to the econotag on
You should see boot up messages similar to this:
CONNECT Size: 62096 bytes Sending rest-server-example_redbee-econotag.bin done sending files. performing ring osc cal crm_status: 0xc0000 sys_cntl: 0x18 ring osc cal complete cal_count: 0x17e17e0 cal factor: 100 hib_wake_secs: 2000 loading rime address from flash. Rime started with address 00:50:C2:AB:C0:00:00:23 nullmac nullrdc, channel check rate 100 Hz, radio channel 26 Tentative link-local IPv6 address fe80:0000:0000:0000:0250:c2ab:c000:0023 Tentative global IPv6 address aaaa:0000:0000:0000:0250:c2ab:c000:0023 Starting 'Rest Server Example' COAP Server
The last line indicates that the server will be using COAP. As an alternative, you can build the server to use HTTP instead with:
make TARGET=redbee-econotag WITH_COAP=0
- Download and install the
Copper Plugin for Firefox provides the
coap: URL access method
as well as an interface to easily send
Download and install the plugin from here:
- Open Copper
Open a new Firefox tab and click on the orange CU button in the lower right.
The initial CU screen will look like this:
Type in the the URL of the coap node with the default port number of "61616":
Don't forget the brackets ( [ ] ) in the URL
Make sure to use the IPv6 address of your coap server. You can get this from the boot up messages or from the webpage served by your border-router.
You must always press Enter after changing the URL.
Now click on the red "./well-known/core" button: this changes the URL
Then click GET to perform a get. You should see an acknowledgement that the GET was successful (returns 200 OK). The payload should return:
Which is are the well-known resources that this node advertises; see the COAP specification for details.
- PUT,POST the
You can PUT or POST to change the state of the LED.
Type in the following URL and press enter:
Be sure to use the proper IP address. For this URL: we will perform
actions on the
led resource with a query string of
In the payload, type:
That is the payload that will be PUT or POSTed. The COAP server detects the mode string and activates the LED accordingly (with the color chosen by the query string).
Then click PUT or POST to perform the request.
You should get a successful return code (200 OK) and the green LED
should turn on. If you PUT/POST
mode=off the led will turn off.
The econotag only has two LEDs: a green and a red. The red LED is used to indicate radio transmission by default and so cannot be used in this demo. The Coniki blue LED is connected to GPIO 43. You can toggle it, but you won't see anything unless you hook something up to this pin.
- Other resources
rest-server-example also provides
The econotag does not have a light sensor. The light resource will always return 0. At a latter date, this sensor will be connected to one of the ADC pins.