nrf/qspi: add lowpower example

embassy-nrf-examples/src/bin/qspi_lowpower.rs

@@ -0,0 +1,81 @@
+#![no_std]
+#![no_main]
+#![feature(min_type_alias_impl_trait)]
+#![feature(impl_trait_in_bindings)]
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+
+use core::mem;
+use defmt::panic;
+use embassy::executor::Spawner;
+use embassy::time::{Duration, Timer};
+use embassy::traits::flash::Flash;
+use embassy_nrf::Peripherals;
+use embassy_nrf::{interrupt, qspi};
+use example_common::*;
+
+// Workaround for alignment requirements.
+// Nicer API will probably come in the future.
+#[repr(C, align(4))]
+struct AlignedBuf([u8; 64]);
+
+#[embassy::main]
+async fn main(_spawner: Spawner, mut p: Peripherals) {
+    let mut irq = interrupt::take!(QSPI);
+
+    loop {
+        let mut config = qspi::Config::default();
+        config.deep_power_down = Some(qspi::DeepPowerDownConfig {
+            enter_time: 3, // tDP = 30uS
+            exit_time: 3,  // tRDP = 35uS
+        });
+
+        let mut q = qspi::Qspi::new(
+            &mut p.QSPI,
+            &mut irq,
+            &mut p.P0_19,
+            &mut p.P0_17,
+            &mut p.P0_20,
+            &mut p.P0_21,
+            &mut p.P0_22,
+            &mut p.P0_23,
+            config,
+        )
+        .await;
+
+        let mut id = [1; 3];
+        q.custom_instruction(0x9F, &[], &mut id).await.unwrap();
+        info!("id: {}", id);
+
+        // Read status register
+        let mut status = [4; 1];
+        q.custom_instruction(0x05, &[], &mut status).await.unwrap();
+
+        info!("status: {:?}", status[0]);
+
+        if status[0] & 0x40 == 0 {
+            status[0] |= 0x40;
+
+            q.custom_instruction(0x01, &status, &mut []).await.unwrap();
+
+            info!("enabled quad in status");
+        }
+
+        let mut buf = AlignedBuf([0u8; 64]);
+
+        info!("reading...");
+        q.read(0, &mut buf.0).await.unwrap();
+        info!("read: {=[u8]:x}", buf.0);
+
+        // Drop the QSPI instance. This disables the peripehral and deconfigures the pins.
+        // This clears the borrow on the singletons, so they can now be used again.
+        mem::drop(q);
+
+        // Sleep for 1 second. The executor ensures the core sleeps with a WFE when it has nothing to do.
+        // During this sleep, the nRF chip should only use ~3uA
+        Timer::after(Duration::from_secs(1)).await;
+    }
+}