==============
Raspberry PI
==============

.. contents:: Indice degli argomenti
.. |date| date::



I2c
========

Follow instrucctions from: https://learn.adafruit.com/adafruits-raspberry-pi-lesson-4-gpio-setup/configuring-i2c , wich is mearly a thing about putting:

/etc/modules::
    i2c-bcm2708 
    i2c-dev


/boot/config.txt::
    dtparam=i2c1=on
    dtparam=i2c_arm=on



Test
---------

Test I2C::

    i2cdetect -y 0

         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
    00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
    10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
    20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
    30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
    40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
    50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
    60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 




Serial
===========

* Test: https://github.com/lurch/rpi-serial-console

In order to have RPi serial -> FTDI USB we need TX/Rx and ground. Always check FTDI V setting: RPI is not 5v tolerant.


Disable serial console
-------------------------

RPi default is to bring up serial to the serial console.

/etc/inittab::
    #Spawn a getty on Raspberry Pi serial line
    T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100


/boot/cmdline.txt ::
    ... 
    console=ttyAMA0,115200 kgdboc=ttyAMA0,115200


In order to use the UART for something different than console login these have to be commented and removed, then reboot (or manage inetd).

Serial test
~~~~~~~~~~~~~~~

In order to test that the line is available launch a serial connection between two hosts::

    conny:  screen /dev/ttyUSB0 115200
    rpi:    screen /dev/ttyAMA0 115200


Arduino - RPi serial test
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We are going to have first a terminal connection on RPi::

    screen /dev/ttyAMA0 9600



Then a sketch running on Arduino (Uno in this case)::

    byte number = 0;

    void setup() {
    byte number = 0;

    void setup() {
      Serial.begin(9600);
    }

    void loop() {
      if (Serial.available()) {
        number = Serial.read();
        Serial.print("character recieved: ");
        Serial.println(number, DEC);
        Serial.flush();
        }
    }



Wiring should be like: http://blog.oscarliang.net/ctt/uploads/2013/05/wiring.png with a Logic level converter. Consider that:

* Rpi can send a Tx -> Arduino with no harm with no leven conversion
* Arduino need at least a voltage divisior to step down to 3v from 5v.
* I2C can be done with no conversion if the RPi is muster and there's no slave pulling up to 5v the line. Seriously: you gotta check that.


Whatever, now let's make a script on RPI to check the serial connection, first install python serial `` apt-get install python3-serial`` ::

    #! /usr/bin/python3

    import serial
    ser = serial.Serial('/dev/ttyAMA0', 9600, timeout=1)
    ser.isOpen()

    sample = "hello"
    ser.write(bytes(sample.encode('ascii')))
    try:
        while 1:
            response = ser.readline()
            print(response)
    except KeyboardInterrupt:
        ser.close()