example: add f072 blocking_adc example

examples/py32f072/src/bin/blocking_adc.rs

@@ -0,0 +1,48 @@
+#![no_std]
+#![no_main]
+#![feature(impl_trait_in_assoc_type)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_time::Timer;
+use py32_hal::rcc::{Pll, PllSource, Sysclk, PllMul};
+use py32_hal::time::Hertz;
+use py32_hal::adc::{Adc, SampleTime, Prescaler};
+use py32_hal::peripherals::ADC;
+use py32_hal::adc;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let mut cfg: py32_hal::Config = Default::default();
+    cfg.rcc.hsi = Some(Hertz::mhz(24));
+    cfg.rcc.pll = Some(Pll {
+        src: PllSource::HSI,
+        mul: PllMul::MUL3,
+    });
+    cfg.rcc.sys = Sysclk::PLL;
+    let p = py32_hal::init(cfg);
+
+    info!("Hello World!");
+
+    let mut adc = Adc::new(p.ADC, Prescaler::Div4);
+    adc.set_sample_time(SampleTime::CYCLES28_5);
+    let mut pin = p.PA7;
+
+    let mut vrefint = adc.enable_vrefint();
+
+    loop {
+        let vrefint_sample = adc.blocking_read(&mut vrefint);
+        let v = adc.blocking_read(&mut pin);
+        info!("value: {}", v);
+        info!("vrefint_sample: {}", vrefint_sample);
+        info!("--> {} - {} mV", v, convert_to_millivolts(v, vrefint_sample));
+        Timer::after_millis(100).await;
+    }
+}
+
+pub fn convert_to_millivolts(sample: u16, vrefint: u16) -> u16 {
+    const VREFINT_MV: u32 = 1200; // mV
+
+    (u32::from(sample) * VREFINT_MV / u32::from(vrefint)) as u16
+}