From 1ee4bb22deb19e93a7c68e04875889e3e4e31c29 Mon Sep 17 00:00:00 2001
From: Jeremy Fitzhardinge <jeremy@goop.org>
Date: Wed, 28 Sep 2022 09:35:19 -0700
Subject: [PATCH] embassy-rp i2c: async (non-blocking) example

Simple example exercising an mcp23017 GPIO expander, configured on
RP2040 GPIOs 14+15 (i2c1) with 8 inputs and 8 outputs. Input bit 0
controls whether to display a mcp23017 register dump.
---
 examples/rp/src/bin/i2c_async.rs | 102 +++++++++++++++++++++++++++++++
 1 file changed, 102 insertions(+)
 create mode 100644 examples/rp/src/bin/i2c_async.rs

diff --git a/examples/rp/src/bin/i2c_async.rs b/examples/rp/src/bin/i2c_async.rs
new file mode 100644
index 00000000..d1a2e3cd
--- /dev/null
+++ b/examples/rp/src/bin/i2c_async.rs
@@ -0,0 +1,102 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_rp::i2c::{self, Config};
+use embassy_rp::interrupt;
+use embassy_time::{Duration, Timer};
+use embedded_hal_async::i2c::I2c;
+use {defmt_rtt as _, panic_probe as _};
+
+#[allow(dead_code)]
+mod mcp23017 {
+    pub const ADDR: u8 = 0x20; // default addr
+
+    macro_rules! mcpregs {
+        ($($name:ident : $val:expr),* $(,)?) => {
+            $(
+                pub const $name: u8 = $val;
+            )*
+
+            pub fn regname(reg: u8) -> &'static str {
+                match reg {
+                    $(
+                        $val => stringify!($name),
+                    )*
+                    _ => panic!("bad reg"),
+                }
+            }
+        }
+    }
+
+    // These are correct for IOCON.BANK=0
+    mcpregs! {
+        IODIRA: 0x00,
+        IPOLA: 0x02,
+        GPINTENA: 0x04,
+        DEFVALA: 0x06,
+        INTCONA: 0x08,
+        IOCONA: 0x0A,
+        GPPUA: 0x0C,
+        INTFA: 0x0E,
+        INTCAPA: 0x10,
+        GPIOA: 0x12,
+        OLATA: 0x14,
+        IODIRB: 0x01,
+        IPOLB: 0x03,
+        GPINTENB: 0x05,
+        DEFVALB: 0x07,
+        INTCONB: 0x09,
+        IOCONB: 0x0B,
+        GPPUB: 0x0D,
+        INTFB: 0x0F,
+        INTCAPB: 0x11,
+        GPIOB: 0x13,
+        OLATB: 0x15,
+    }
+}
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+
+    let sda = p.PIN_14;
+    let scl = p.PIN_15;
+    let irq = interrupt::take!(I2C1_IRQ);
+
+    info!("set up i2c ");
+    let mut i2c = i2c::I2c::new_async(p.I2C1, scl, sda, irq, Config::default());
+
+    use mcp23017::*;
+
+    info!("init mcp23017 config for IxpandO");
+    // init - a outputs, b inputs
+    i2c.write(ADDR, &[IODIRA, 0x00]).await.unwrap();
+    i2c.write(ADDR, &[IODIRB, 0xff]).await.unwrap();
+    i2c.write(ADDR, &[GPPUB, 0xff]).await.unwrap(); // pullups
+
+    let mut val = 1;
+    loop {
+        let mut portb = [0];
+
+        i2c.write_read(mcp23017::ADDR, &[GPIOB], &mut portb).await.unwrap();
+        info!("portb = {:02x}", portb[0]);
+        i2c.write(mcp23017::ADDR, &[GPIOA, val | portb[0]]).await.unwrap();
+        val = val.rotate_left(1);
+
+        // get a register dump
+        info!("getting register dump");
+        let mut regs = [0; 22];
+        i2c.write_read(ADDR, &[0], &mut regs).await.unwrap();
+        // always get the regdump but only display it if portb'0 is set
+        if portb[0] & 1 != 0 {
+            for (idx, reg) in regs.into_iter().enumerate() {
+                info!("{} => {:02x}", regname(idx as u8), reg);
+            }
+        }
+
+        Timer::after(Duration::from_millis(100)).await;
+    }
+}