add support for pdm microphones in nrf driver

examples/nrf/src/bin/pdm.rs

@@ -0,0 +1,33 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::info;
+use embassy_executor::Spawner;
+use embassy_nrf::interrupt;
+use embassy_nrf::pdm::{Config, Pdm};
+use embassy_time::{Duration, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_p: Spawner) {
+    let p = embassy_nrf::init(Default::default());
+    let config = Config::default();
+    let mut pdm = Pdm::new(p.PDM, interrupt::take!(PDM), p.P0_01, p.P0_00, config);
+
+    loop {
+        pdm.start().await;
+
+        // wait some time till the microphon settled
+        Timer::after(Duration::from_millis(1000)).await;
+
+        const SAMPLES: usize = 2048;
+        let mut buf = [0i16; SAMPLES];
+        pdm.sample(&mut buf).await.unwrap();
+
+        info!("samples: {:?}", &buf);
+
+        pdm.stop().await;
+        Timer::after(Duration::from_millis(100)).await;
+    }
+}