The “Chronvertor” Time Protocol Simulation Module

(Now Replaced by the Chronvertor2) 

v2.0 firmware ((Feb 2014) adds a “MasterPulse” periodic impulse mode for stepping electro-mechanical clocks. (external driver interface required)

Chronvertor time protocol simulation module

The Chronvertor 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)
    • 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
  • New “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 CR2032 coin-cell.
  • The module time/date can be very accurately set by syncing it with an external  GPS  $GPRMC 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 (CR2032)  for the RTC timekeeping battery backup.

(The CR2032 lithium battery is not supplied with the module due to current postal restrictions.)

Main Power consumption:

4mA (with LED flashing)

3mA (LED off)

Backup timekeeping battery power consumption:

0.85µA (Estimated run-time >10 years (or the shelf life of the CR2032 battery))


PCB only – 33mm X 27.5mm X 1.6mm (1.3” X 1.1” X 0.06”) (PCB has rounded corners)

Height approx 20mm (0.79”) including battery holder

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 11 Grams (0.4 oz)


For latest v2.0 firmware (released 09/02/2014) (includes “MasterPulse” mode)

Chronvertor User Manual v2.1 (For firmware v2.0)

For all previous firmwares:

Chronvertor manual v1.1
Additional information

The Chronvertor can also decode a GPS time protocol sent via the serial com port of a Windows PC using our free “Nixiesync” windows software that was originally supplied with the “Six tube Nixie clock kit”.

“Nixiesync” sends the PC’s local time. If you want the Chronvertor to then output UTC, change the timezone offset and dst settings to convert back to UTC.

The default Com port is Com1 but you can change it to a different port using a parameter after the program name e.g. for Windows 7, change the program icon target settings to:

“C:\Program Files (x86)\NixieSync\NixieSync.exe” com3

The program can be run from any folder, no installation is required and it does not store any settings on the PC. It works with windows versions from Windows 98 to Windows 7.

The “Carrier” option

I often get asked about using the “Carrier” option to sync a nearby Radio Controlled clock or watch. This can be achieved by connecting a short length of wire or radio coil and placing the clock/watch very close (a few inches away at most).

Instructions on how to do this are here:

Adding an Aerial for the “Carrier” option

Using a USB to serial converter 

If your PC doesn’t have a serial port, a USB to RS232 serial converter can be used.

Your serial converter should be a true RS232 type. (DO NOT use a “LOGIC” “TTL” type).

(The compatible RS232 types are usually fitted with a 9 pin male D-Type connector (DB9))

Using a GPS module

  • A GPS module that outputs NMEA data at a serial baudrate of 4800 baud can be used with the Chronvertor
  • The Chronvertor serial interface connection requires true RS232 voltage levels (not logic levels).

As many cheaply available GPS modules don’t meet these requirements, I have produced a document to show how to adapt a Ublox NEO-6M GPS module to work at the required baud-rate and modify the serial interface.

Using a NEO-6M GPS module
Customer Reviews
  1. John has connected modules to two Nixie clocks that require a GPS or DCF77 time source and published a review with photos on his website.
  2. Jan has fitted a Chronvertor to his “Measure of Time” Nixie clock. (YouTube Video).
Buy the replacement Chronvertor2 module from the Shop