STM32 gotchas
126.Not all STM32F730 are created equal, and some don't have the built-in HS USB PHY

The STM32F722 is a "lower-end", but still very capable member of the 'F7 family, featuring the Cortex-M7 core. As other "performance" STM32 ('F2, upper-end 'F4, all 'F7 and 'H7), it also features two USB OTG modules, which both have connected a built-in Full-Speed PHY, but one of them - usually marked OTH_HS1 - has also an ULPI interface, to which an external High-Speed PHY can be connected.

In the STM32F723, there is an internal High-Speed PHY, connected to this OTG_HS module internally. This makes it the only STM32, which offers a native single-chip HS USB solution.

ST also makes a "Value-line" version of these chips, marked STM32F730. As with other "Value-line" models, they are simply the same chips which has seen less testing at smaller temperature range, so parts of memories and some peripherals are not guaranteed to work and thus are effectively unavailable. It is not uncommon for ST to offer several models of the same family under one "Value-line" model number - for example, the STM32F030 consists in fact of 3 different models, depending on their memory size.

Nonetheless, in this case, the difference is quite significant - in STM32F730 in 64-pin and 100-pin packages the internal HS PHY is absent, so they are equivalent of the 'F722; whereas in the 144-pin and 176-pin packages the internal HS PHY is present, so they are equivalent to 'F723.

1. ST does not maintain consistent marking of modules across families, for example in the 'H743 RM it calls both OTG modules as OTG_HS, despite the fact that one of them is capable only of FS, exactly as in other families.