From 236662c748eab43a701bf4f43570b191ec2c1158 Mon Sep 17 00:00:00 2001
From: Adrian Wowk <dev@adrianwowk.com>
Date: Wed, 2 Jul 2025 20:53:26 -0500
Subject: [PATCH] rp: add pio spi examples

---
 examples/rp/src/bin/pio_spi.rs       | 63 +++++++++++++++++++++++++++
 examples/rp/src/bin/pio_spi_async.rs | 65 ++++++++++++++++++++++++++++
 2 files changed, 128 insertions(+)
 create mode 100644 examples/rp/src/bin/pio_spi.rs
 create mode 100644 examples/rp/src/bin/pio_spi_async.rs

diff --git a/examples/rp/src/bin/pio_spi.rs b/examples/rp/src/bin/pio_spi.rs
new file mode 100644
index 000000000..1fbe235e5
--- /dev/null
+++ b/examples/rp/src/bin/pio_spi.rs
@@ -0,0 +1,63 @@
+//! This example shows how to use a PIO state machine as an additional SPI
+//! (Serial Peripheral Interface) on the RP2040 chip. No specific hardware is
+//! specified in this example.
+//!
+//! If you connect pin 6 and 7 you should get the same data back.
+
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_rp::{
+    bind_interrupts,
+    peripherals::PIO0,
+    pio,
+    pio_programs::spi::{Config, PioSpiProgram, Spi},
+    spi::Phase,
+};
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    PIO0_IRQ_0 => pio::InterruptHandler<PIO0>;
+});
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    info!("Hello World!");
+
+    // These pins are routed to differnet hardware SPI peripherals, but we can
+    // use them together regardless
+    let mosi = p.PIN_6; // SPI0 SCLK
+    let miso = p.PIN_7; // SPI0 MOSI
+    let clk = p.PIN_8; // SPI1 MISO
+
+    let pio::Pio { mut common, sm0, .. } = pio::Pio::new(p.PIO0, Irqs);
+
+    // The PIO program must be configured with the clock phase
+    let program = PioSpiProgram::new(&mut common, Phase::CaptureOnFirstTransition);
+
+    // Construct an SPI driver backed by a PIO state machine
+    let mut spi = Spi::new_blocking(
+        &mut common,
+        sm0,
+        clk,
+        mosi,
+        miso,
+        &program,
+        // Only the frequency and polarity are set here
+        Config::default(),
+    );
+
+    loop {
+        let tx_buf = [1_u8, 2, 3, 4, 5, 6];
+        let mut rx_buf = [0_u8; 6];
+
+        spi.blocking_transfer(&mut rx_buf, &tx_buf).unwrap();
+        info!("{:?}", rx_buf);
+
+        Timer::after_secs(1).await;
+    }
+}
diff --git a/examples/rp/src/bin/pio_spi_async.rs b/examples/rp/src/bin/pio_spi_async.rs
new file mode 100644
index 000000000..5abf6fc71
--- /dev/null
+++ b/examples/rp/src/bin/pio_spi_async.rs
@@ -0,0 +1,65 @@
+//! This example shows how to use a PIO state machine as an additional SPI
+//! (Serial Peripheral Interface) on the RP2040 chip. No specific hardware is
+//! specified in this example.
+//!
+//! If you connect pin 6 and 7 you should get the same data back.
+
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_rp::{
+    bind_interrupts,
+    peripherals::PIO0,
+    pio,
+    pio_programs::spi::{Config, PioSpiProgram, Spi},
+    spi::Phase,
+};
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    PIO0_IRQ_0 => pio::InterruptHandler<PIO0>;
+});
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    info!("Hello World!");
+
+    // These pins are routed to differnet hardware SPI peripherals, but we can
+    // use them together regardless
+    let mosi = p.PIN_6; // SPI0 SCLK
+    let miso = p.PIN_7; // SPI0 MOSI
+    let clk = p.PIN_8;  // SPI1 MISO
+
+    let pio::Pio { mut common, sm0, .. } = pio::Pio::new(p.PIO0, Irqs);
+
+    // The PIO program must be configured with the clock phase
+    let program = PioSpiProgram::new(&mut common, Phase::CaptureOnFirstTransition);
+
+    // Construct an SPI driver backed by a PIO state machine
+    let mut spi = Spi::new(
+        &mut common,
+        sm0,
+        clk,
+        mosi,
+        miso,
+        p.DMA_CH0,
+        p.DMA_CH1,
+        &program,
+        // Only the frequency and polarity are set here
+        Config::default(),
+    );
+
+    loop {
+        let tx_buf = [1_u8, 2, 3, 4, 5, 6];
+        let mut rx_buf = [0_u8; 6];
+
+        spi.transfer(&mut rx_buf, &tx_buf).await.unwrap();
+        info!("{:?}", rx_buf);
+
+        Timer::after_secs(1).await;
+    }
+}