adc_input: make synchronous and simplify

src/adc_input.rs

@@ -7,31 +7,40 @@ use stm32f4xx_hal::{
     stm32::ADC1 as ADC,
 };
 
+/// ADC Input
 pub struct AdcInput {
     /// unused but consumed
     _pin: Pin<Analog>,
-    pub adc: Adc<ADC>,
+    adc: Adc<ADC>,
 }
 
 impl AdcInput {
+    /// Configure pin into analog mode
     pub fn new<MODE>(adc: ADC, pin: Pin<MODE>) -> Self {
         let pin = pin.into_analog();
         let adc_config = AdcConfig::default()
             .scan(Scan::Enabled)
             .continuous(Continuous::Single)
-            .end_of_conversion_interrupt(Eoc::Conversion)
-            .clock(Clock::Pclk2_div_8);
+            .clock(Clock::Pclk2_div_2);
         let mut adc = Adc::adc1(adc, true, adc_config);
 
         adc.configure_channel(&pin, Sequence::One, SampleTime::Cycles_480);
-        adc.start_conversion();
         
         AdcInput { _pin: pin, adc }
     }
 
+    /// Enable the ADC,
+    /// run a conversion
+    /// disable the ADC
     pub fn read(&mut self) -> u16 {
-        let sample = self.adc.current_sample();
-        self.adc.start_conversion();
-        self.adc.sample_to_millivolts(sample)
+        let adc = &mut self.adc;
+        adc.enable();
+        adc.clear_end_of_conversion_flag();
+        adc.start_conversion();
+        let sample = adc.current_sample();
+        let result = adc.sample_to_millivolts(sample);
+        adc.wait_for_conversion_sequence();
+        adc.disable();
+        result
     }
 }

src/adc_input/mod.rs

@@ -1,39 +0,0 @@
-use core::cell::RefCell;
-use cortex_m::interrupt::Mutex;
-use stm32f4xx_hal::{
-    gpio::{gpioa::PA3 as Pin},
-    stm32::{NVIC, ADC1 as ADC, interrupt, Interrupt},
-};
-
-mod input;
-use input::AdcInput;
-
-static ADC_INPUT: Mutex<RefCell<Option<AdcInput>>> = Mutex::new(RefCell::new(None));
-static ADC_VALUE: Mutex<RefCell<Option<u16>>> = Mutex::new(RefCell::new(None));
-
-pub fn setup<MODE>(nvic: &mut NVIC, adc: ADC, pin: Pin<MODE>) {
-    let adc_input = AdcInput::new(adc, pin);
-    cortex_m::interrupt::free(|cs| {
-        ADC_INPUT.borrow(cs)
-            .replace(Some(adc_input))
-    });
-    nvic.enable(Interrupt::ADC);
-}
-
-pub fn read() -> Option<u16> {
-    cortex_m::interrupt::free(|cs| {
-        ADC_VALUE.borrow(cs).borrow_mut().take()
-    })
-}
-
-#[interrupt]
-fn ADC() {
-    cortex_m::interrupt::free(|cs| {
-        let mut adc_input = ADC_INPUT.borrow(cs)
-            .borrow_mut();
-        let value = adc_input.as_mut()
-            .map(|adc_input| adc_input.read());
-        *ADC_VALUE.borrow(cs)
-            .borrow_mut() = value;
-    });
-}

src/main.rs

@@ -26,6 +26,7 @@ use stm32f4xx_hal::{
 use smoltcp::time::Instant;
 
 mod adc_input;
+use adc_input::AdcInput;
 mod net;
 mod server;
 use server::Server;
@@ -88,7 +89,7 @@ fn main() -> ! {
     let mut led_red = Led::red(gpiob.pb14.into_push_pull_output());
 
     info!("ADC init");
-    adc_input::setup(&mut cp.NVIC, dp.ADC1, gpioa.pa3);
+    let mut adc_input = AdcInput::new(dp.ADC1, gpioa.pa3);
 
     info!("Eth setup");
     stm32_eth::setup_pins(
@@ -113,10 +114,8 @@ fn main() -> ! {
                 led_blue.on();
                 let now = timer::now().0;
                 if now - last_output >= OUTPUT_INTERVAL {
-                    let adc_value = adc_input::read();
-                    adc_value.map(|adc_value| {
+                    let adc_value = adc_input.read();
                     write!(server, "t={},pa3={}\r\n", now, adc_value).unwrap();
-                    });
                     last_output = now;
                 }
                 led_blue.off();