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Associate II
July 10, 2026
Question

STM32U3C5: HSP Interrupts

  • July 10, 2026
  • 2 replies
  • 36 views

I am trying to generate an interrupt when the HSP finishes a processing list so that I don’t need to poll it. However, I can’t seem to figure out how to do this.

There are some things in the STM32U3 reference manual that make me confused:

In section 19.4.12 HSP interrupt controller (HITC), there are four interrupt lines:
• An interrupt line handling errors (hsp_err_it)

• An interrupt line handling various hardware events (hsp_evt_it)

• An interrupt line handling events generated by the SPE processing (hsp_fwevt_it)

• A global interrupt is asserted when one of the previous interrupts is asserted (hsp_it)

However, in Section 19.3 HSP Implementation, Table 143 shows that neither hsp_err_it, hsp_evt_it, nor hsp_fwevt_it are implemented in the U3 series. If this is the case, does that mean that hsp_it is just never asserted? Is it possible to notify the application when a processing list has finished without polling for a flag?

Section 5.13.5 of UM3360: HSP processing functions says that the SET_FLAG function can generate an interrupt when it sets a bit in HSP_PFCTEVT_ISR, but is this mapped to one of the unimplemented lines?

I am using STM32U3C5

2 replies

AQBAuthor
Associate II
July 10, 2026

My workaround for now is to use a SetTrgo function at the end of the processing list, and this Trgo triggers a DMA channel to move a single dummy byte. I can then use the DMA’s callback as the HSP complete callback.

ST Technical Moderator
July 15, 2026

Hi ​@AQB 

Only global interrupt is implemented in STM32U3C5/B5. hsp_err_it hsp_fwevt_it hsp_evt_it are not connected. So to notify about a HW event or processing list completion, you need to poll for a flag as implemented in HAL or use an alternate mechanism such as a TRGO DMA callback with same flags.

About SET_FLAG statement is generic. On STM32U3C5/B5, it does not mean the event lines are physically connected as separate interrupt sources. 

To give better visibility on the answered topics, please click on "Best answer" on the reply which solved your issue or answered your question.Best regards,FBL