This is an helper class for php-Arduino communications on Linux
After a week of googling and tests, i build this Class to communicate from php running on Linux (master) to an Arduino board via serial USB.
The master message max length is 60 char (serial Arduino rx buffer limit), the response (from Arduino) as no limits. The '\n' char is used internally as terminator. The protocol uses CRC8 to insure correctness. In case of error the message is resended 3 times before exit in error state.
A Bash script (serialArduino.sh) is used to setup the USB device on Linux, after startup or USB (re)connection. The serial communication is open for every message: in the Bash script the DTR pin is disabled to avoid the Arduino auto reset. (see: https://playground.arduino.cc/Main/DisablingAutoResetOnSerialConnection)
TROUBLESHOOTING
- ERROR LCRC: bad CRC Linux -> Arduino
- ERROR ACRC: bad CRC Arduino -> Linux
- ERROR CODE: sended a command code not implemented in Arduino
- ERROR SERIAL: USB not plugged, Arduino not running or php fails on open the serial device. In this case the file 'status.txt' contains: 'stty: /dev/ttyACM0: Inappropriate ioctl for device' ?? Solution: hot disconect and reconnect Arduino USB
SETUP
see ArduinoLinuxSerial.php file.
CONCLUSIONS
Now you can develop MySQL and web enabled Arduino applications only working on Arduino and PHP.
To keep ligth the Arduino Sketch, you can port all not realtime logic to PHP side.
At the end your application will works on MXQ+Arduino UNO even 24/7 with only 20 Watt AC power, and can
be controlled by smartphone via WiFi.
What more?
Enjoy.
I am very interested in using TVboxes (like MXQ) as dedicated WEB servers with Arduino extensions: so about (Linux + Android)-Arduino USB serial communication I tested many solutions:
Using ArduinoLinuxSerial (https://github.com/msillano/ArduinoLinuxSerial) the Master is php, and you need the
serial driver (uses devices like /dev/ACMx or /dev/USBx). It is blocking the master and the php->Arduino message
is limited to 60 char. Fast and robust (CRC and repetions). Useful with simple and fast Arduino responses.
Using USBphpTunnel (https://github.com/msillano/USBphpTunnel) the master is Arduino, and the Android app uses
ports like /dev/bus/dev/00X/00Y, so you don't need the serial driver. It is blocking the master (arduino) and
it allows big messages. It works in background of the main php program. Useful for data logging and RT.
Using USBphpTunnel_Fifo (https://github.com/msillano/USBphpTunnel_fifo) the master is php. It is NOT blocking the
master, allows payload up to 4k, allows concurrence (many users via WIFI). Works in background, and it is no fast
(depending from polling Arduno frequence, 5-15 sec. plus processing time). Well placed for long Arduino processes
(like waiting user actions).