Easiest way to communicate with arduino through PHP

[StoopKid]

I would like to be able to communicate with an Arduino with a website I am hosting on my Raspi.I have had trouble in the past trying to do GPIO stuff with php, I would end up having to edit a file then have a c++ program read the file to know what to do. And that c++ program wouldn't run as root automatically so I would have to run it in a tmux window so that wiringPi would work. I tried a bunch of tutorials to make wiringPi not require sudo but nothing worked. It was a real mess....

So what is the easiest way to do this? I just want to send a tiny amount of info to an arduino(an atmega328p, to be more particular, I'd like to avoid having to use the entire arduino) from a php script.

[riklaunim]

Serial connection maybe?

[StoopKid]

That's what I was thinking but I was hoping someone had some experience with it so I don't jump into another thing that just gives me headaches.

[StoopKid]

So yeah, trying to do serial with php and c++ are both giving me tons of problems. While I work on it, are there any suggestions for efficient alternatives?

[B.Goode]

I haven't tried it, so I don't know if it is either possible or efficient, but how about a framework like firmata? There is a standard firmata sketch supplied with the arduino ide. There are php implementations/interfaces for firmata.

https://github.com/ThomasWeinert/carica-firmata

https://github.com/oasynnoum/phpmake_firmata

[asandford]

You can use MQTT (to publish messages) from php without requiring root.

A subscribing program can run as root and control GPIO.

Google MQTT Mosquitto

[mahjongg]

dont forgot to add level converters to the serial connection, to account for the fact that the PI uses 3V3 levels, while an arduino normally uses 5V.

[DougieLawson]

You can use MQTT (to publish messages) from php without requiring root.

A subscribing program can run as root and control GPIO.

Google MQTT Mosquitto

With an ethernet shield on my Arduino and Nick O'Leary's MQTT library I can run MQTT on the Arduino.
http://knolleary.net/arduino-client-for-mqtt/

I've not yet tried running that with my SPI enc28j60 ethernet connected to my Arduino. That's an experiment for another day.