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The chrono project is an ElN project done at the end of the first semester. It consists in conrtolling a stepper motor which moves a pointer in a clockwise direction. It will emulate a stop watch.

Chrono in Action


The basic specification is the following one:

  • On reset, the pointer moves to the start position (12 o'clock), it is given by a Reed sensor.
  • When pos 2 button (Start) is pressed, the pointer will start counting seconds.
  • When pos 3 button (Stop) is pressed, the pointer stops and waits at the actual location.
  • When pos 1 button (Reset) is pressed, the pointer resets to the start position (12 o'clock).

as optional task a pos4 button (Set) can be pressed in order to halt the pointer, but the stop watch is still counting. By a second push of the set button the pointer moves to the actual stop watch time.


The system consists of

Motor control circuit

The Chrono Stepper motor powered with 8-12 V. The power circuit contains an H-bridge controlled by digital signals. On the power board, a 5 V regulator generates the proper voltage for powering the FPGA board.

Stepper motor

The Stepper motor is controlled by a L6207 H-bridge driver. The Stepper motor itself has a resolution of 1.8degree (Full step) and works with 4 coils.

Hall sensors

The hall sensor is a switch which is working with the hall effect. If a magnet is close to the sensor, the contact closes. For the projects 1 hall sensors are used to identify the 12 o'clock position.

FPGA board

The main board is called FPGA-EBS and is the school's main development board. It features many different interfaces and a Xilinx Spartan xc3s500e FPGA.

For additional information see the FPGA-EBS page.

Buttons and LEDs

The Button and Led parallelboard can be attached to the FPGA-EBS and has 4 additional buttons and 8 additional leds which you can use.

Toplevel Design

Getting started

In order to start the projects you should do the following:

Additional Information

Additional informations for collaborators

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