test: tests for temperature without linker error

examples/temperature.rs

@@ -1,19 +1,17 @@
-// NOTE: This is at least unreliable and likely wrong
+#![cfg_attr(not(test), no_main)]
+#![cfg_attr(not(test), no_std)]
 
-#![no_main]
-#![no_std]
+#[cfg(not(test))]
+extern crate panic_halt;
 
-use defmt::{debug, info};
 use hal::adc::{Adc, Ready, VRef, VTemp};
 use hal::calibration::{VtempCal30, VtempCal130};
-use panic_probe as _;
-
-use defmt_rtt as _; // global logger
-
-use cortex_m_rt::entry;
 use hal::{pac, prelude::*, rcc::Config};
 
-#[entry]
+use defmt::{debug, info};
+use defmt_rtt as _; // global logger
+
+#[cfg_attr(not(test), cortex_m_rt::entry)] // this is the entrypoint unless testing
 fn main() -> ! {
     let dp = pac::Peripherals::take().unwrap();
     let cp = cortex_m::Peripherals::take().unwrap();
@@ -44,20 +42,27 @@ fn main() -> ! {
     info!("tsense_cal1: {:?}", (30, tsense_cal1));
     info!("tsense_cal2: {:?}", (130, tsense_cal2));
 
-    delay.delay_ms(50_u16);
+    // read a few values into void, maybe this will help get that thing started
+    for _ in 0..20 {
+        let _ = read_temp_mv(&mut adc, 1.0);
+        delay.delay_ms(10_u16);
+    }
+
     let vref_actual: u16 = adc.read(&mut VRef).unwrap();
     let vref_factor = vref_cal as f32 / vref_actual as f32;
-    debug!(
+    info!(
         "vref actual={} calibration={} => factor={}",
         vref_actual, vref_cal, vref_factor
     );
 
+    delay.delay_ms(10_u16);
+
     let mut temp_c;
     let mut temp_mv;
     loop {
         temp_mv = read_temp_mv(&mut adc, vref_factor);
         temp_c = temp_mv_to_c(temp_mv, tsense_cal1, tsense_cal2);
-        info!("Temperature: {:03}mv, {:04}c", temp_mv, temp_c as i32);
+        info!("Temperature: {:03}mv, {:04}°C", temp_mv, temp_c as i32);
         delay.delay_ms(500_u16);
     }
 }
@@ -74,3 +79,26 @@ fn temp_mv_to_c(temp: f32, ts_cal_1: (i32, u16), ts_cal_2: (i32, u16)) -> f32 {
         * (temp - ts_cal_1.1 as f32)
         + ts_cal_1.0 as f32
 }
+
+#[cfg(test)]
+mod tests {
+    // run these tests: cargo test --example=temperature --target=x86_64-unknown-linux-gnu
+    use super::temp_mv_to_c;
+
+    #[test]
+    fn test_mv_to_c() {
+        // values read out from my board as logged
+        // after flashing and running
+        //
+        // First is the temperature for that calibratoin, second is the measured voltage at that
+        // temperature
+        let calibration_data = [(30, 673), (130, 912)];
+        for caldat in calibration_data {
+            let degrees: f32 =
+                temp_mv_to_c(caldat.1 as f32, calibration_data[0], calibration_data[1]);
+            assert_eq!(caldat.0 as f32, degrees);
+            dbg!(caldat);
+            dbg!(degrees);
+        }
+    }
+}