How can I use the flywheel timer?

This article applies to:
STM300

QUESTION

I need a very precise timer for synchronous networks. I heard I could use the flywheel timer for this purpose. How to do it?

ANSWER

To use the flywheel Timer you will need a Wrist Watch Christal, we recommend the CM200C
In order to evaluate the flywheel timer on a EVA320 you will need:

  • EVA320
  • STM300 module soldered on the piggyback board
  • X1=CM200C crystal
  • C1=22pF, C2=27pF capacitor



Do the following HW modifications:

  1. Remove R1 and R2 resistors from the piggyback board
  2. Solder C1 and C2
  3. Solder X1





Do the following SW modifications:

  1. Open DolphinStudio and in the menu Utilities->Calibrate Flywheel Timer start the calibration procedure. Follow the instructions
  2. You can test the functionality of the XTAL using the example EO3000I_API\Examples\Flywheel

Remember: Before writing an application that uses the Flywheel Timer, make sure the WXTAL pins are selected in the I/O configuration as showed in the picture below!




Additional see an example schematic how to connect the crystal directly to the Dolphin module without piggyback: