Acesse: https://www.gov.br/pt-br/servicos/assinatura-eletronica

During my investigations I discovered there are 3 ways to use PTP on microcontrollers:

1) Using a MCU with Ethernet MAC supporting PTP

2) Using a PHY that detects Start of Frame (SOF)/Start of Frame Delimiter (SFD) and generates a signal to the processor

3) An external PHY with PTP IEEE-1588 support, such as Texas Instruments DP83640

https://timebeat.app/blog/ieee-1588-explained

https://community.st.com/stm32-mcus-embedded-software-32/ethernet-hal-driver-reworked-by-st-and-available-in-22q1-preview-now-available-on-github-10052

https://community.st.com/stm32-mcus-embedded-software-32/ethernet-hal-driver-reworked-by-st-and-available-in-22q1-preview-now-available-on-github-10052

https://community.st.com/stm32-mcus-embedded-software-32/getting-started-with-ptp-ieee-1588-10702

https://www.ti.com/document-viewer/lit/html/SSZTAU5

https://www.designworldonline.com/ethernet-switch-with-ptp/

https://maisvch.com/blog/ieee-1588-ptp-vs-ntp-industrial-time-synchronization/

Very interesting project:

https://www.youtube.com/watch?v=UvV2CH5il3Q