Connect Raspberry Pi & Arduino USB bidirectional

How to connect an Arduino to a raspberry pi via USB bidirectional.

The raspberry reads all from the serial and prints it. Next it reads a textile from a webpage and sends the text (one word) to serial, next a random car to the Arduino. Arduino got a LCD attached and shows the data it got via serial. It sends back the seconds it run and a string. The example is at this time without real use, it is just for testing the bidirectional serial connection.

Using Python on the raspberry side. Change the port to what you find out:

import serial
import time
import random
import urllib2
import feedparser
def read_all(port, chunk_size=200):
    """Read all characters on the serial port and return them."""
    if not port.timeout:
        raise TypeError('Port needs to have a timeout set!')

    read_buffer = b''

    while True:
        # Read in chunks. Each chunk will wait as long as specified by
        # timeout. Increase chunk_size to fail quicker
        byte_chunk =
        read_buffer += byte_chunk
        if not len(byte_chunk) == chunk_size:

    return read_buffer
#end def

cars = ["Ford", "Volvo", "BMW", "VW"]

ser = serial.Serial(
    port = '/dev/ttyACM0',
    baudrate = 9600,
    parity = serial.PARITY_NONE,
    stopbits = serial.STOPBITS_ONE,
    bytesize = serial.EIGHTBITS,
    timeout=0.5, # IMPORTANT, can be lower or higher

#s = serial.Serial('/dev/ttyACM0', 9600) # Namen ggf. anpassen

time.sleep(2) # der Arduino resettet nach einer Seriellen Verbindung, daher 


d = feedparser.parse('')
dlen = len(d['entries'])
dnr = 0
    while True:
        nb = "01234567890123456789012345678901"
        text = ""
        data_str = []
        data_str = read_all(ser)
        #nb = raw_input('Choose it: ')
        #nb = cars[random.randint(0,3)] + "x"
            #nb = d['entries'][dnr]['title'].encode('utf-8').strip() + "x"
            nb = d['entries'][dnr]['title'].encode('utf-8').strip() 
            dnr += 1 
            if (dnr > dlen -1):
                d = feedparser.parse('')
                dlen = len(d['entries'])
                dnr = 0
            response = urllib2.urlopen('')
            text =
        ll = len(text)
        text2 = text + " " + nb[0:33-ll] + "\n"
        #text2 = nb[16-ll:33-ll] + "y"
except KeyboardInterrupt:

And this is the Arduino part:


Example code for the Adafruit RGB Character LCD Shield and Library

This code displays text on the shield, and also reads the buttons on the keypad.
When a button is pressed, the backlight changes color.


// include the library code:
#include <Wire.h>
#include <Adafruit_RGBLCDShield.h>
#include <utility/Adafruit_MCP23017.h>

// The shield uses the I2C SCL and SDA pins. On classic Arduinos
// this is Analog 4 and 5 so you can't use those for analogRead() anymore
// However, you can connect other I2C sensors to the I2C bus and share
// the I2C bus.
Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();

// These #defines make it easy to set the backlight color
#define RED 0x1
#define YELLOW 0x3
#define GREEN 0x2
#define TEAL 0x6
#define BLUE 0x4
#define VIOLET 0x5
#define WHITE 0x7

byte nr;
char myString[] = "Hello MArius";
String readString;
long previousMillis = 0;
long interval = 1000;

void setup() {
// Debugging output
// set up the LCD's number of columns and rows: 
lcd.begin(16, 2);

// Print a message to the LCD. We track how long it takes since
// this library has been optimized a bit and we're proud of it :)
int time = millis();
lcd.print("Hello, Marius!");
time = millis() - time;
//Serial.print("Took "); Serial.print(time); Serial.println(" ms");
lcd.setCursor(0, 1);


uint8_t i=0;
void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
//lcd.setCursor(0, 1);
// print the number of seconds since reset:

unsigned long currentMillis = millis();

if(currentMillis - previousMillis > interval) {
// save the last time you blinked the LED 
previousMillis = currentMillis;
//do nothing at the moment 


nr = 1;

if (Serial.available() > 0) {
//nr =;
//myString = Serial.readln();
//Serial.print("Folgender char wurde empfangen: ");
//Serial.println(nr, DEC);

char c =; //gets one byte from serial buffer
readString += c; //makes the string readString
//readString = "";

if (c == 'x') {
lcd.print(" <");
readString = "";



uint8_t buttons = lcd.readButtons();

if (buttons) {
if (buttons & BUTTON_UP) {
lcd.print("UP ");
if (buttons & BUTTON_DOWN) {
lcd.print("DOWN ");
if (buttons & BUTTON_LEFT) {
lcd.print("LEFT Marius");

if (buttons & BUTTON_RIGHT) {
lcd.print("RIGHT Paulina");
if (buttons & BUTTON_SELECT) {
lcd.print("SELECT ");

Postgresql – Tipps and Tricks

Using PLSQL for setting Grants:


r record;
SELECT sequence_name, sequence_schema FROM information_schema.sequences WHERE sequence_schema = 'xxx'
-- can do some processing here
EXECUTE ' Grant all on ' || r.sequence_schema || '.' || r.sequence_name || ' to userXY' ;
--RETURN NEXT r; -- return current row of SELECT
LANGUAGE plpgsql;

— und ausführen
select xxx.set_all_sq_grants();

more about Postgres PLSQL: Fun with Functions.



Text to UML and others

Was searching for tools for documentation, doing graphics out of Text:

Very good summary link: Text to UML.

Most features: Planttext

Clean and easy, Sequence and FlowChart:

Also very fast to use:

And one for ERM:

One more



Binding Blade Inductrix FPV pro with Spektrum DX6i

I had problems with binding my new Blade Industrie FPV Pro to my Spektrum DX6i. Looked like it bonded, but nothing happened. This helped my out: link to forum.

So what to do:

You have to adjust (all) the travel to max (here 125%). Note: Use the sticks to switch between high and low. The other thing is to arm the motors: Switch flaps on and off after 2 seconds.

Hope this helps


Münchens super geheime Einkauftipps

Johannes’ München Schnäppchenfinder

Hier eine Sammlung meiner Geheimtipps für Münchenbesucher.

Dr. Schnell Reinigungsmittel für Profis, kleiner Outlet-Store auch für Amateure. Hier wird das Zeugs hergestellt, das immer auf den Putzwägen steht. Gut und besser als das beworbene Consumer Zeugs. Extra-Tipp: Milizid: Gegen Kalk, Gastro-Pur: Gegen Fett. – Wirkt Hammer, aber Handschuhe anziehen! Taunusstraße 19, Mo – Do von 8 bis 17 Uhr / Fr von 8 bis 14 Uhr

Spina Italienischer Feinkost (Groß-) Händler, eine gigantische Wein- und Nudelauswahl. Aber auch so ziemlich alles an italienischen Lebensmitteln (Öle, Fische, Brot, Süßigkeiten ….). Und dazu noch günstig! Extra-Tipp: Tomaten aus der Dose, 10 mal besser als was in D verkauft wird. Maria-Probst-Str. 49, Montag – Freitag: 08.30 – 18.00 Uhr,
Samstags: 07.30 – 14.00 Uhr

Maerz:  Sehr hochwertige (und hochpreisige) (Woll) Strickwaren, Outlet, Bayerwaldstr. 7, 81737, Mo – Fr 11 – 18 Uhr, Sa 9.30 – 14 Uhr

Raspberry Pi as NAS with OpenMediaVault and Wifi

Be warned, the Raspberry Pi with wlan is a slow nas. But I wanted to build one and there are no full instructions for it. So here are the steps to follow.

I used this instruction, but some things are missing and so I put everything down in short form:

Download the OMV Image here.

Use Etcher to flash it on SD card.

Insert card into raspberry, connect network cable. Wait (!) not only wait for the first time login, wait.. Raspberry upgrades in the background. Just do nothing(!) and wait more. About 10 to 40 min till the raspberry reboots again!

Now, login for the first time as root. Change Password.
Change Keyboard Layout if you don’t use english one:

dpkg-reconfigure keyboard-configurationcheck if your Wifi works:

ifconfig -aDo you see your wlan? If not, start at top.

Add your wifi with:

ifconfig -aNow it could be a good idea to tell the router to fix the ip addresses.
sudo shutdown now
remove power
connect USB-Sticks, Harddisks, whatever. Be aware to use HD (also the 2,5) with their own Power(!).

Repower your raspberry.

And now first time to go to the OMV Web Interface.
Point your browser to one of the ip addresses.
Login admin/openmediavault

Change Password and Hostname in “System”

Format (Physical disks) then add Disk (file systems) in “Storage”
Select and Mount your Disk (file systems).

“Access Right Management”
Add a user in “Access Right Management”.
Add folder(s) in “Access Right Management”.
In “shared folders” mark folder and “give privileges” to your user.

“Settings” -> Enable in “SMB/CIFS”
“Shares” -> add your folder

OK, now it’s the time to test your new nas. Go to your PC or Mac (smb://…your..ip…) and give it a try.

Raspberry Pi, OpenMediaVault, NAS, Wifi, WLAN, error