These programs exercise the DMA_IRQ_0 interrupt handlers on the RP2040 / RP2350, which are shared between audiocore/audiopwmio (audio DMA) and rp2pio (PIO background read/write DMA).

They were written to validate the change in issue #9992 (moving audio_dma.c off the fixed isr_dma_0() linker symbol and onto irq_add_shared_handler(), with rp2pio registering its own shared handler). They use only public APIs that predate that change, so each program should behave identically before and after it — that is the point: they are regression tests, not feature tests.

Each goes through the background-DMA path (background_write / background_read), which is interrupt-driven. The blocking write/readinto/ write_readinto calls poll instead and do not use the DMA IRQ, so they are deliberately not used here. The audio sample is created with single_buffer=False so audio also uses the interrupt-driven (double-buffered) DMA path rather than the no-interrupt single-buffer chaining path.

• GP13 — PWM audio output. Connect to an amplifier/speaker, or just leave it; the test does not require you to hear anything, only that playback keeps running.
• GP2 — PIO output pin.
• GP3 — PIO input pin (loopback test only). For a meaningful loopback, connect GP2 to GP3 with a jumper. Without the jumper the read still completes (it just reads whatever the floating/pulled pin sees), so the DMA path is still exercised.

Copy one file at a time to CIRCUITPY/code.py and watch the serial console. A successful run ends with a PASS: line. A hang (no further output) or a RuntimeError/crash/safe-mode indicates a regression in the shared DMA IRQ handling.