10BASE-T1S MAC-PHY HAT

This HAT brings 10BASE-T1S Ethernet directly to a Raspberry Pi. It is based on the Analog Devices ADIN1140, a single-port MAC-PHY with an integrated Ethernet MAC and PHY.

Unlike a conventional Ethernet interface, 10BASE-T1S uses one balanced wire pair as a shared multidrop bus. The HAT supports both CSMA/CD and PLCA operation, allowing deterministic access on a properly configured multidrop network.

What is being reviewed

This review covers the first hardware revision of the ADIN1140-based T1S HAT, in particular:

• ADIN1140 power supply, decoupling and 25 MHz clock circuit
• SPI, IRQ and Raspberry Pi GPIO interface
• 10BASE-T1S coupling, common-mode choke and ESD protection
• selectable 100 Ω split termination and shield/reference concept
• connector arrangement for practical multidrop installations
• EMC-relevant schematic and layout considerations

Software, Linux device-tree integration and enclosure design are not part of this review.

Review scope

Please report functional issues, violations of the ADIN1140 data-sheet requirements and recommendations, and clearly useful improvements.

The first person to identify a confirmed functional hardware bug in this HAT receives one free of charge. A qualifying bug must prevent the intended function from working or violate a data-sheet specification or recommendation.

Specific questions

I would especially appreciate feedback on:

• Is the T1S coupling and selectable split termination correct for multidrop installations?
• Have I missed any mandatory ADIN1140 supply, clock or SPI requirements?
• Is the common-mode choke, ESD protection and shield/reference concept appropriate?
• Would you expect a different connector, termination or diagnostic arrangement in an industrial installation?