Android receipt printer library

NEW Version (2015-02-14) uploaded. Old version deleted

Just uploaded my new Android receipt printer library to GitHub.
Via an USB OTG cable you can directly connect your receipt printer to your mobile phone or tablet.

So far I implemented some ESC/POS commands for EPSON receipt printer.

the lib itself is located under

I also create a sample project:

When you want to implement the lib in your own project, don’t forget to set the USB permissions in the AndroidManifest.xml

<permission android:name=""/>

Check the example for more details:

Have fun.


RFID / Arduino : Copy a card with known keys,


Today I want to show you how to copy a Mifare classic card with the arduino mega and the rfid-rc522 module.


  • Card Reader
  • Arduino Mega
  • Arduino Library
  • Existing RFID Card ( in this example a Mifare Classic 1k )
  • New empty RFID Card

Card Reader

Recently I bought a RFID-RC522 Module from aliexpress( ~ 5$ ) .

RFID Module Board RC522
RFID Module Board RC522
Connect the board with the Arduino Mega.
 * Pin layout should be as follows:
 * Signal Pin Pin Pin
 * Arduino Mega MFRC522 board
 * ------------------------------------------------------------
 * Reset      5    RST
 * SPI SS    53    SDA
 * SPI MOSI  51    MOSI
 * SPI MISO  50    MISO
 * SPI SCK   52    SCK
 * #Note: Code will work not with Arduino UNO because of not enough SRAM

Arduino Mega

I used an Arduino  MEGA 2560, because UNO had to lees RAM. Note: We have to read a 1K card and keep this in memory.

Arduino Library

For accessing there exists a lot of arduino libraries in the net. I do not know which library I used exactly, think it was from here.

Existing RFID Card

mifare_classic_1K In my example I used an existing Mifare Classic 1K card. This piece of code gives you info about your card. Serial.print(" PICC type: "); // Dump PICC type byte piccType = mfrc522.PICC_GetType(mfrc522.uid.sak); Serial.println(mfrc522.PICC_GetTypeName(piccType));

New empty RFID Card

Any new card. Please note that the UID number of an existing card couldn’t be copied. The UID number of an new card is normally read only, and programmed by the manufactory of the cards. Except, so called >> Chinese magic rfid card<<. My code example do not try to write the read UID number to the new card.


In general I am a little bit lazy to give you a big explanation about the code. Just download it and go through… But okay some info’s I want to give you: Please note: serial baud rate is 57600 Please do not forget to change your keys

 byte KeyA_List[][6] =
 {150,161,162,166,164,165}, // Sector 0
 byte KeyB_List[][6] =
 {134,135,136,137,138,139}, // Sector 0

Basic flow: Idea is to read a card , dump this information


and also add the KEY A and KEY B infos to the dumped data. see comments in my code

// Special note on KEY_A / KEY_B
// see datasheet
// When the sector trailer is read, the key bytes are blanked out by returning logical zeros. If
// Key B is configured to be readable, the data stored in bytes 10 to 15 is returned, see

So this is my first version.

Mini Thermal Printer QR701

Ich habe mir einen Mini Thermal Printer QR701 (EH48-20243)  aus China bestellt.
Der Printer druckt eine Testseite wenn man hinten auf der Platine den Schalter betätigt.

Mini Thermal Printer

Bei mir jedoch nicht….
Jetzt habe ich den Grund gefunden, ich habe ein zu schwaches Netzteil verwendet (1 A ).Mit einem stärkeren hat es funktioniert..

Noch ein Tipp:
Pinbelgeung beachten !
RX Pin ist Blau
TX Pin ist Grün
DTR Pin ist Gelb ( den unbedingt auf GND legen )

Hier noch einige Dokumente…
701print driver board –> pdf

701print driver board  –> word

Here is my sketch I used for testing:

I also make some modifications on the Adafruit_Thermal library.
(which is not any more needed if you are using the latest library version, see example form library)

It is basically the baud rate: –> Changed to 9600 !
diff Adafruit thermal printer lib

Latest Adafruit Library is on git hub

Check also a other blog about the Mini Thermal Printer:

Maycom FR-100

On the Internet you will find on some pages a schematic of the Maycom FR-100 radio scanner. When i compared the schematic with my device i found out that this schematic is old.

So some of the used chips i found out.

Schematic, Parts

Pin layout of the 2×10 pin connector.

  • Pin 6  -> GND
  • Pin 9   -> BAT  ( Power )
  • Pin 10 -> PWR_ON
  • Pin 11 -> IC 26
  • Pin 15 -> GND
  • Pin 13 -> SPK

to be continued

USB-CAN USB to CAN Bus Converter Adapter + USB Cable


Hab mir gerade so ein Teil von Aliexpress bestellt..

um 18,38€ incl. Versand.

Falls wer Treiber sucht.
Serial Chip ist der CH340T verbaut.
Treiber findet man unter
Wenn man 64 Bit Windows hat ist die DRVSETUP64.exe heraus zu den anderen Dateien zu kopieren.

Eventuell auch hier

Eine passende CAN Sniffer Software (USB-CAN(V5.00E).exe) findet man hier (nicht immer erreichbar und in chinesisch).

Und hier noch ein Downloadlink:

If someone needs drivers, check out the following links:

Driver for usb serial CH340 :
Monitor Software USB-CAN(V5.00E).exe :





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