The design should be as simple as possible and vandalism protected. The electronics are primitive, contains an MCU, a slot for reading the Payment Card, a driver for 1-bit audio, one color LED and one touch button for payment confirmation. In standby mode, the color of the LED is yellow. The passenger inserts card into the slot and confirms payment by touching the surface of button. If the card does not contain information about payment of the current trip in this vehicle, its amount is deducted from the card's content and operation is accompanied by a voice message about the withdrawn amount and the flashing of the LED (green). If this is an erroneous retry of payment, or there is not enough units on the card, or the unknown format of the card data and other errors, the LED flashes red and a corresponding voice message issued.

It is supposed to use cards with cheap chips of the SLE4432/PCF2032 and SLE4442/PCF2042 series, since them first 32 bytes can be protected from further change.

Proposed content of the card data (data format is not considered in this document)

The first 32 bytes consists:

  • Unique ID od Card Manufacturer
  • Unique Card Number
  • Transport type code (excluding route taxis):
    - all types (trolley, bus and tram)
    - trolleybus
    - bus
    - tram
    - trolley and bus
    - trolley and tram
    - tram and bus
  • The cost of one trip on the bus
  • The cost of one trip in a tram
  • The cost of one trip in a trolleybus
  • The initial number of units of payment in this type of card
  • The control code formed, by a special algorithm

Starting with the 33-rd byte, variable information is written:

  • Date and time of the last payment (without taking into account the type of transport)
  • Vehicle Unique Identifier in which the last payment was made (it is recorded by the Cashless Terminal)
  • The control code, formed by a special algorithm to exclude forgery