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David, You question the reason for 10BASE-T1S to define PMD and list the following potential reason: The second would be to enable interoperable implementation of the PMD function as a separate instantiation from the PCS, PMA and other functions. To achieve this the PMD service interface (the interface between
the PMA and PMD) would be defined as a chip-to-chip compatibility interface, no mechanical connector would be specified. This would enable a 'system' (PCS, PMA, other functions) chip with a 'digital' interface to a 'driver' (PMD) chip. I assume that this is
the reason for providing a PMD sublayer for the 10BASE-T1S PHY. My understanding is that PHY integration into an MCU may result too small a common mode range for many of the target applications, because a low voltage process (small geometry) is necessary for cost effective implementation of the large
amount of MCU logic. Similar non-Ethernet systems such as CAN and RS-485 implement a separate transceiver chip in a high voltage (large geometry) process to achieve adequate common mode range for more demanding environments. It would be useful to maintain
a similar option for 10BASE-T1S. Note that these transceivers are very simple and can have few pins. Regards, David D. Brandt To unsubscribe from the STDS-802-3-10SPE list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-10SPE&A=1 |