1 PPS (GPS) STM32F429

[PSEBA.1]

Hello,

I want to develop a firmware to synchronize an Ocxo on a 1PPS GPS reference signal. I have a Nucleo card with a stm32f429 to do the first tests. The configuration: 1 1PPS input (1 second), 1 10Mhz input reference of the OCXO, 1 DAC output, the measurement method is: between the 2 rising edges of the 1PPS, I count the number of timer overflows, taking the decimal value of the result x 2exp16 my result is 57600 for 10Mhz exactly, in theory everything is fine but how to code all this on a stm32! can you tell me the main things to implement to start my code ?

Best regards.

Sébastien (France)

[TDK]

> in theory everything is fine but how to code all this on a stm32

You know the basics, count the pulses to determine the difference between the two clocks.

You can't change the output on an OCXO, but you can know what the drift is and use that in your calculations.

It would be easier to use a 32-bit timer which would not overflow.

Try it, if something isn't working, show your work. You are effectively measuring the frequency of the PPS signal. Here is one example out of many:

How to measure frequency using Timers - STMicroelectronics Community