Hi Mod,

I have this in my config.h file:

// TIME AND LOCATION -------------------------------------------------- see https://onstep.groups.io/g/main/wiki/6-Configuration#TLS
#define TIME_LOCATION_SOURCE          DS3231 //    OFF, DS3231 (I2c,) DS3234 (Spi,) TEENSY (T3.2 internal,) or GPS source.       Option
                                          //         Provides Date/Time, and if available, PPS & Lat/Long also.

...

#define PPS_SENSE                     ON //    OFF, ON* enables PPS (pulse per second,) senses signal rising edge.           Option
                                          //         Better tracking accuracy especially for Mega2560's w/ceramic resonator.

For the wiring: I used this small module that is really intended for RasPi s


It has connections for supply and ground, and SCL/SDA for I2C. The fifth one is NC (Not Connected). From this pin I soldered a resistor to supply and a small piece of wire to pin 3 of the IC that is on the board. This pin is the INT/SQW pin and carries the 1 PPS signal





and the electrical connection to the OnStep controller is as follows



BE AWARE that the SDA and SCL lines on the OnStep controller are NOT the pins on the CNC shield that are labelled SDA/SCL, but the SDA/SCL pins on the R32 board itself.

Hope this helps,

BR/Onno