How to use two QSPIs of STM32U575RG simultaneously

[SourFish]

As shown in the figure, when using one QSPI, the other becomes unselectable.

[KDJEM.1]

Hello @SourFish ,

 

According to the datasheet DS13737 Rev 10 Table 2. STM32U575xx features and peripheral counts; two OCTOSPIs are available only in Muxed mode in STM32U575RG.

 

So, you need to configure the OCTOSPI with Quad SPI-- MULTIPLEXED mode:

 

Thank you.

Kaouthar

 

[SourFish]

Thanks for your reply!

When I choose Data [3:0] for OCTOSPI1, the OCTOSPI2 can only use the same pin group. that's means I can't transmit data at same time, right?

 

[KDJEM.1]

Hello @SourFish;

 

 When Multiplexed mode is enabled, both OCTOSPI1/2 signals are mixed over one OCTOSPI/XSPI I/O port except the OCTOSPI1/2_NCS / XSPI1/2_NCS1/2 pins.

So, the OCTOSPIs are time-multiplexed over the same bus.

You cannot transmit data at the same time because an minimum number of cycles needed to switch from an OCTOSPI to another can be configured.

This internal timer guarantees a latency between the falling edge of the REQ signal of the active OCTOSPI (the active one releases the bus), and the rising edge of the ACK signal to the requesting OCTOSPI (the bus is granted to the requesting one). The REQ2ACK_TIME field of the configuration register OCTOSPIM_CR defines the duration.

 

Thank you.

Kaouthar

[SourFish]

Thanks for support.

Best regard.