The “Chronvertor2” Time Protocol Simulation Module

(Retired Product)


The Chronvertor2 is an updated hardware design of my original Chronvertor.

The serial interface has been simplified to use 5V logic levels and the battery is now fitted to the top of the board to save space.

The firmware has been updated to use 9600 baud serial communication for configuration, GPS synchronisation and simulation.

It can now also obtain time sync from NMEA GPxRMC datagrams received from various satellite constellations such as GLONASS, BeiDou or mixed $GN datagrams if you use a compatible GPS module.

Chronvertor2 is a module containing a very accurate battery backed Maxim DS3231 RTC (Real Time Clock) chip working with a Microchip PIC Microcontroller to output the time and date as either a GPS NMEA datagram or a WWVB, DCF77, MSF or JJY radio time protocol.

It automatically takes care of DST (Daylight Saving Time) changes around the world and provides for time-zone offsets to generate any local time.

The RTC time and date can be initially set-up by either connecting it to a GPS module for a few seconds or by serial commands sent by a PC terminal program.

  • Simulates any one of the following serial time protocols:
    • GPS NMEA Time datagram ($GPRMC) at 9600 baud.
    • WWVB (USA) Radio time protocol.
    • MSF (UK) Radio time protocol.
    • DCF77 (Germany) Radio time protocol.
    • JJY (Japan) Radio time protocol.
  • Carrier wave (60,77.5 & 40kHz)  generation options for radio protocols.
  • Automatic DST (Daylight Saving Time) adjustment for most countries and custom rules
  • World Time Zone offset settings allow any local time to be generated
  • Automatic Leap Year adjustment
  • The module automatically outputs the correct weekday code for radio time protocols
  • “MasterPulse” mode – impulses can be generated at periodic intervals to step or synchronise mechanical “Slave” clocks. (external driver interface required).
  • Very accurate timekeeping. (within  ± 5.4 seconds per month or better)
    • Timekeeping fine adjustment can improve accuracy and compensate for crystal “aging”
    • Each module is tested and fine-calibrated after construction to improve on the published RTC timekeeping accuracy
    • Time is battery-backed with a long life lithium CR1220 coin-cell.
  • The module time/date can be very accurately set by syncing it with an external  GPS  $GxRMC data connection.
  • Time/date can also be set by serial commands from a PC terminal so that you can set any time or date in the current century.
  •  Small size with low power consumption making it ideal for replacing existing radio or GPS time sources.
  • Could be used for testing or synchronising radio controlled clocks/watches where they cannot receive the appropriate radio signal.
  • All configuration settings are safely stored in the microcontrollers’ EEPROM memory.
  • Configuration settings can be reset back to factory defaults if you wish.

Power supply requirements:

5 Volts DC maximum (Regulated) for the module.

3 Volts lithium coin cell (CR1220)  for the RTC timekeeping battery backup.

(The CR1220 lithium battery is not supplied with the module due to shipping restrictions.)

Main Power consumption:

4mA (with LED flashing)

3mA (LED off)

Backup timekeeping battery power consumption:

0.85µA (Estimated run-time >3 years (or the shelf life of the CR1220 battery))


PCB only – 30.5mm X 27.5mm X 1.6mm (1.2” X 1.1” X 0.06”) (PCB has rounded corners)
Height approx 12mm (0.47”)

Timekeeping Accuracy:

Unadjusted RTC accuracy ±2ppm from 0°C to +40°C. (about ± 5.4 seconds per month)

(accuracy can be improved further by fine tuning settings stored in EEPROM memory).

Crystal Aging:

First year: ±1ppm

0-10 Years ±5ppm (Manufacturer’s estimate)


Approx 7 Grams (0.25 oz)

Chronvertor2 User Manual
Additional information

Using a GPS module

  • A GPS module that outputs NMEA data at a serial baudrate of 9600 baud can be used with the Chronvertor2

I have produced a document to show how to connect a Ublox NEO-6M or NEO-M8N GPS module here.

Using a GPS module with Chronvertor2