Add example of using pin.observe

examples/observe.rs

@@ -0,0 +1,63 @@
+//! ## Origin
+//!
+//! This code has been taken from the stm32g0xx-hal project and modified slightly to support
+//! STM32G4xx MCUs.
+
+//#![deny(warnings)]
+#![deny(unsafe_code)]
+#![no_main]
+#![no_std]
+
+mod utils;
+extern crate cortex_m_rt as rt;
+
+use fugit::ExtU32 as _;
+use hal::{
+    adc::AdcClaim as _,
+    comparator::{ComparatorExt, ComparatorSplit, Config},
+    delay::SYSTDelayExt as _,
+    gpio::GpioExt,
+    observable::Observable as _,
+    rcc::RccExt,
+    stm32,
+};
+use rt::entry;
+use stm32g4xx_hal::{self as hal, adc::config::SampleTime, delay::DelayExt as _};
+
+#[entry]
+fn main() -> ! {
+    let cp = cortex_m::Peripherals::take().unwrap();
+    let dp = stm32::Peripherals::take().unwrap();
+    let mut rcc = dp.RCC.constrain();
+
+    let gpioa = dp.GPIOA.split(&mut rcc);
+
+    let (comp1, ..) = dp.COMP.split(&mut rcc);
+
+    let (pa1, [pa1_token]) = gpioa // <- The pin to keep track of
+        .pa1
+        .into_analog()
+        .observe();
+    let pa0 = gpioa.pa0.into_analog(); // <- Reference voltage
+
+    // Only pa1_token and pa0 consumed here
+    let comp1 = comp1.comparator(pa1_token, pa0, Config::default(), &rcc.clocks);
+    let _comp1 = comp1.enable(); // <-- TODO: Do things with comparator
+
+    let mut delay = cp.SYST.delay(&rcc.clocks);
+    let mut adc = dp.ADC1.claim_and_configure(
+        stm32g4xx_hal::adc::ClockSource::SystemClock,
+        &rcc,
+        stm32g4xx_hal::adc::config::AdcConfig::default(),
+        &mut delay,
+        false,
+    );
+
+    // Can not reconfigure pa1 here
+    loop {
+        // Can still use pa1 here
+        let sample = adc.convert(pa1.as_ref(), SampleTime::Cycles_640_5);
+        defmt::info!("Reading: {}", sample);
+        delay.delay(1000.millis());
+    }
+}