Arduino mirror image, orientation problem with display MAX7219

How to use MAX7219 LED Matrix with Arduino

Good Libraries to use with the MAX7219 LED are: LED Scrolling

You’ll find lot’s of examples after you install the libraries in the Arduino IDE.

Arduino mirror image, orientation problem with display MAX7219

How to solve problem with the LED matrix MAX7219 and the MD_MAX72xx.h Library

If you have problems with mirroring and/or orientation find following line and try following solutions, Choose one:





Raspberry pi & waveshare 2.7 e-ink Display & python

Start with a headless raspberry, no need to connect monitor, keyboard:

Find the raspberry in your router and connect with ssh. Useullay steps are:

sudo raspi-config
sudo reboot

(neu einloggen)

sudo apt-get update -y
sudo apt-get upgrade -y

Here’s some example python code for drawing text horizontal on the waveshare e-ink display. You’ll find also a example where to find the length of text where to break lines. This examples reads some small text from a web site and looks up a rss feed for the weather.

Install the fonts

sudo apt-get install ttf-mscorefonts-installer

Install libraries

sudo apt-get install git-core
git clone git://
cd wiringPi

sudo apt-get install wiringpi
sudo dpkg -i wiringpi-latest.deb
gpio -v
tar zxvf bcm2835-1.59.tar.gz
cd bcm2835-1.59
sudo make check
sudo make install
  • Install Python2 libraries
sudo apt-get update
sudo apt-get install python-pip
sudo apt-get install python-pil
sudo apt-get install python-numpy
sudo pip install RPi.GPIO
sudo pip install spidev
  • Install Python3 libraries
sudo apt-get update
sudo apt-get install python3-pip
sudo apt-get install python3-pil
sudo apt-get install python3-numpy
sudo pip3 install RPi.GPIO
sudo pip3 install spidev

pip install feedparser

(Before running the API codes we provided, you should start up the corresponding core drivers of the interfaces. In the ready-to-use system image file, both I2C and SPI are set to Enable by default, but the serial port is still in the terminal debugging function mode.)

  1. Enable the I2C function. Run the following command to configure your Raspberry Pi board:
     sudo raspi-config

    Select Advanced Interface Options -> I2C -> yes, to start up the I2C core driver. Then you also need to modify the configuration file. Run the following command to open the configuration file:

    sudo nano /etc/modules

    Add the following two lines to the configuration file

    Press the keys Ctrl+X to exit, and input Y to save the settings. Then, reboot the module to make the settings take effect.
  2. Enable the serial function. The serial port of RPi is set to serial terminal debugging function mode by default. If you want the serial port services as a common IO, you should modify the settings on the RPi. When the terminal debugging function is disabled, you cannot access RPi board via the serial port any more. If you want to control the RPi, you may need to enable the debugging function of the serial port again.
    sudo raspi-config

    Select Advanced Interface Options -> Serial. Select the option no can disable the serial debugging function. And then, the serial port can be used for serial communication. And select the option yes can enable the serial debugging function. You should reboot the module to make the settings take effect.

Note: the serial port on Raspberry Pi 3 Model B is unusable, because Pin 14 and Pin 15 is connected to the on-board Bluetooth model.
  1. Start up the spi function, run the following command:
    sudo raspi-config

    Select Advanced Interface Options -> I2C -> yes, to start up I2C core driver.


# coding: utf8
 #  width 176
 #  height 264

import epd2in7
from PIL import Image
from PIL import ImageFont
from PIL import ImageDraw
import time
import urllib2
import feedparser
import datetime

def getLengthText(myTextInput, myFont, pixels):
    #font = ImageFont.truetype('/usr/share/fonts/truetype/freefont/msttcorefonts/comic.ttf', 28)
    #font = ImageFont.truetype("arial", 20)
    myText = myTextInput
    mlen = 0
    mlen = len(myText)
    w, h = myFont.getsize(myText)
    while pixels < w:
        myText = myText[0:mlen-2]
        mlen = len(myText)
        w, h = myFont.getsize(myText)
    return mlen

def addText(myImage,myText, myFont, xx,yy):
    #font = ImageFont.truetype('/usr/share/fonts/truetype/freefont/msttcorefonts/comic.ttf', 28)
    #font = ImageFont.truetype("arial", 20)
    w, h = myFont.getsize(myText)
    mask ='1', (w, h), 255)
    draw2 = ImageDraw.Draw(mask)
    draw2.text((0, 0), myText, font = myFont, fill = 0)
    mask = mask.rotate(90, expand=True)
    myImage.paste(mask, (xx,epd2in7.EPD_HEIGHT - w - yy ))

def main():
    epd = epd2in7.EPD()

    image ='1', (epd2in7.EPD_WIDTH, epd2in7.EPD_HEIGHT), 255)    # 255: clear the image with white
    draw = ImageDraw.Draw(image)
    font = ImageFont.truetype("arial", 18)
    font2 = ImageFont.truetype("comic", 24)
    font3 = ImageFont.truetype("arial", 28)

    # get text from a feed
    #d = feedparser.parse('')
    d = feedparser.parse('')
    dnr = 0
    dlen = len(d['entries'])
    oberbayern = 0
    for n in range(dlen):
        actentry = d['entries'][n]['title'].encode('utf-8').strip()
        print str(n) + " " + actentry[0:8]
        if actentry[0:8] == "Oberbaye":
            oberbayern = n
        if actentry[0:8] == "München":
            muenchen = n
    print d['entries'][oberbayern]['title'].encode('utf-8').strip()
    print d['entries'][muenchen]['title'].encode('utf-8').strip()
    nb = d['entries'][oberbayern]['title'].strip()
    # get text from a website
    ttext = "err"
            #response = urllib2.urlopen('')
            response = urllib2.urlopen('')
            ttext =
            ttext = "err2"

    # add to display

    # first Line
    grad = u'°'
    #entlang umgerechnet oben 1,1 nach 1,264/2
    draw.line((0, 264, 0, 0), fill = 0)
    draw.line((1, 264, 1, 0), fill = 0)
    addText(image,"%H:%M %d.%m."), font3, 5, 6)
    addText(image, ttext + grad, font3, 5, 182)
    # horizontal unter der schrift:
    draw.line((38, 264, 38, 0), fill = 0)
    draw.line((39, 264, 39, 0), fill = 0)
    # senkrechte Linien, wenn quer gesehen
    draw.line((0, 264-180+5, 39, 264-180+5), fill = 0)
    draw.line((0, 264-180+4, 39, 264-180+4), fill = 0)
    draw.line((0, 263, 39, 263), fill = 0)
    draw.line((0, 262, 39, 262), fill = 0)

    draw.line((0, 0, 39, 0), fill = 0)
    draw.line((0, 1, 39, 1), fill = 0)

    muc = "München"
    mstr = d['entries'][muenchen]['title'].strip()
    mstr2 = mstr[mstr.find("):")+3:]

    xlen = 0
    xlen = getLengthText(mstr2,font, 264)
    mstr3 = mstr2[0:xlen]
    msRest = mstr2[xlen:]
    xlen = getLengthText(msRest,font, 264)
    mstr4 = msRest[0:xlen]

    addText(image, mstr3, font, 40, 0)
    addText(image, mstr4, font, 60, 0)
    #addText(image, "012345678901234567890123456789", font, 60, 0)

    xlen = 0
    xlen = getLengthText(nb,font, 264)
    nb1 = nb[0:xlen]
    nbRest = nb[xlen:]
    xlen = getLengthText(nbRest,font, 264)
    nb2 = nbRest[0:xlen]
    nbRest = nbRest[xlen:]
    xlen = getLengthText(nbRest,font, 264)
    nb3 = nbRest[0:xlen]
    nbRest = nbRest[xlen:]
    xlen = getLengthText(nbRest,font, 264)
    nb4 = nbRest[0:xlen]
    nbRest = nbRest[xlen:]
    xlen = getLengthText(nbRest,font, 264)
    nb5 = nbRest[0:xlen]
    addText(image, nb1, font, 80, 0)
    addText(image, nb2, font, 100, 0)
    addText(image, nb3, font, 120, 0)
    addText(image, nb4, font, 140, 0)
    addText(image, nb5, font, 160, 0)
    #addText(image, "abcdef", font, 140, 0)
    #addText(image, "abcdef", font, 160, 0)

    # display images

if __name__ == '__main__':

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