According to the RP235x datasheet, there are 6 spare IRQs which can be used for software interrupts: | IRQ | Interrupt Source | |-----|-------------------| | 46 | `SPAREIRQ_IRQ_0` | | 47 | `SPAREIRQ_IRQ_1` | | 48 | `SPAREIRQ_IRQ_2` | | 49 | `SPAREIRQ_IRQ_3` | | 50 | `SPAREIRQ_IRQ_4` | | 51 | `SPAREIRQ_IRQ_5` | However, these are not exported by this crate.