mirror of
https://github.com/cesanta/mongoose.git
synced 2024-12-15 01:29:00 +08:00
73 lines
2.0 KiB
Plaintext
73 lines
2.0 KiB
Plaintext
|
= Raspberry Pi camera/LED demo
|
||
|
|
|
||
|
|
== Overview
|
||
|
|
|
||
|
|
The link:/[demo] consists of web app providing access to a webcam and a LED attached to a RaspberryPi.
|
||
|
|
The device is assumed to have a limited bandwidth towards the server hosting the web app.
|
||
|
|
|
||
|
|
== Objective
|
||
|
|
|
||
|
|
The demo shows how to use websockets to communicate bidirectionally with an embedded device using standard protocols.
|
||
|
|
|
||
|
|
It also shows that it's possible to use Smart.c to develop also the cloud endpoint and expose WebSocket and RESTful APIs
|
||
|
|
easy to integreate with modern web stacks.
|
||
|
|
|
||
|
|
== How it works
|
||
|
|
|
||
|
|
image::docs/arch.png[]
|
||
|
|
|
||
|
|
There are two components, once with runs on the device (`device_side`) and one that runs on a stronger machine
|
||
|
|
and with more bandwidth (`cloud_side`).
|
||
|
|
|
||
|
|
The device app connects to the cloud app via websocket and sends a new jpeg frame as fast as the underlying `raspistill` camera
|
||
|
|
grabbing application can handle. The device automatically attempts reconnecting.
|
||
|
|
|
||
|
|
The cloud side serves the webapp static pages and serves an MPJEG image on `/mpjg`.
|
||
|
|
The MPJEG image handler blocks all the clients until a JPEG frame arrives via websocket
|
||
|
|
and then every client will recieve a copy of the frame.
|
||
|
|
|
||
|
|
The web app can turn on and off the LED via a RESTful api accessible via the `/api` handler.
|
||
|
|
|
||
|
|
== Installation
|
||
|
|
|
||
|
|
=== Server side
|
||
|
|
|
||
|
|
----
|
||
|
|
git clone https://github.com/cesanta/mongoose
|
||
|
|
cd mongoose/examples/web_demo
|
||
|
|
make cloud_side && ./cloud_side 0.0.0.0:8080
|
||
|
|
----
|
||
|
|
|
||
|
|
=== Raspberry Pi
|
||
|
|
|
||
|
|
The instructions provided here are tailored for the Raspbian distribution.
|
||
|
|
|
||
|
|
==== Dependencies
|
||
|
|
|
||
|
|
jpegoptim::
|
||
|
|
apt-get install jpegoptim
|
||
|
|
|
||
|
|
camera::
|
||
|
|
run raspi-config and enable camera
|
||
|
|
|
||
|
|
==== LED
|
||
|
|
|
||
|
|
In order to access the led on your link:http://www.qdh.org.uk/wordpress/?page_id=15[HotPi]
|
||
|
|
board you need to export the gpio pins:
|
||
|
|
|
||
|
|
----
|
||
|
|
for i in 22 23 24; do
|
||
|
|
echo $i >/sys/class/gpio/export
|
||
|
|
echo out >/sys/class/gpio/gpio$i/direction
|
||
|
|
chgrp pi /sys/class/gpio/gpio$i/value
|
||
|
|
done
|
||
|
|
----
|
||
|
|
|
||
|
|
==== Build and run
|
||
|
|
|
||
|
|
----
|
||
|
|
git clone https://github.com/cesanta/mongoose
|
||
|
|
cd mongoose/examples/web_demo
|
||
|
|
make device_side && ./device_side yourserver:8080
|
||
|
|
----
|