USB Interactive Button with Display

This button is used as part of the easySagra project.

The button is used to request printing of an order ticket. The display indicates the number of orders waiting in the queue.

The “button with display” is interfaced and powered through *USB*. Actually it used a standard serial converter like prolific PL2303. USB port is just for convenience of connecting, but is not mandatory. The device could be interfaced via standard RS-232 (with addition of a driver) and powered with external psu.


Production (aka MaETech BCD-4)



  • USB phisical interface
  • Standard Serial Port interface (over usb), 9600baud 8n1
  • A button as input
  • A 3-digit 7-segment display shows the number
  • A buzzer and an additional led (for illuminated buttons)


As shown in photo , the serial-usb converter is detached from the circuit as it is cheaper.

No schematics was drawed so please refer to wiring notes in the firmware files.

The micro is an Atmel ATmega8 at 8MHz.


Firmware in C, target avr device. Fuses H:D9, L:EF. button2.tar

Test Software

Test software in Qt, target desktop. qt_button2_test.tar


Table of contents


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