Feel confused about "USART with SPI" in datasheet of STM32G0B1RE

[AlanCui4080]

See DS13560 Rev 4 (Datasheet of STM32G0B1RE)please. On the right side, it said "Six USARTs with master/slave synchronous SPI; three supporting ISO7816 interface, LIN, IrDA capability, auto baud rate detection and wakeup feature". I'm now writing courseware for my students and i cannot explain what is "USART with SPI", seems to not be "Serial peripheral interface".

[FBL]

Hi @AlanCui4080 

USART can be configured to mimic SPI's behavior, allowing it to communicate with SPI devices or other USARTs in synchronous mode. This feature provides flexibility for designers to use the USART for SPI communication when SPI interfaces are limited or already in use.

[Andrew Neil]

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@AlanCui4080 wrote:

 "USART with SPI", seems to not be "Serial peripheral interface".

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What makes you say that?

Note that the ST datasheets focus on physical/electrical specifications - for full details on the operation of peripherals, see the Reference Manual; eg,

Probably also worth checking for any Application Notes on the subject

https://www.st.com/en/microcontrollers-microprocessors/stm32g0b1re.html#documentation

[Tesla DeLorean · Accepted solution]

Well that's a bit scary..

With the U(S)ART, the S means Synchronous, ie with a clock. ST's implementation, unlike some from yore, has a single clock output (input in Slave mode), so both TX and RX come via the same clock, isn't that adequate to meet the definition of a serial peripheral interface, in the broad definition of the concept? An SPI EEPROM, probably not, but the world of choices is somewhat larger than that.

Here signalling and framing is used, rather than a chip select.

Not going to work well where the interface expects independent clocks, or probably SDLC / HDLC either.

And not as remotely helpful as Atmel/Microchip's SERCOM model.

ST's model is more "Imagine the possibilities", and perhaps the ability to disabuse the peripheral to achieve what you need, especially with legacy or non-conforming hardware.

https://www.st.com/resource/en/reference_manual/rm0444-stm32g0x1-advanced-armbased-32bit-mcus-stmicroelectronics.pdf