Increase upper threshold and add lower threshold with yellow light

rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "nightly"

src/main.rs

@@ -1,5 +1,6 @@
 #![no_std]
 #![no_main]
+#![feature(exclusive_range_pattern)]
 
 use embedded_alloc::Heap;
 use panic_halt as _;
@@ -43,13 +44,14 @@ const HEAP_SIZE: usize = 1024;
 
 const XTAL_FREQ_HZ: u32 = 12_000_000u32;
 const MVG_AVG_COUNT: u16 = 20;
+const DISPLAY_UPDATE_INT_TICKS: u32 = 500_000;
+const SENSOR_READ_INT_TICKS: u32 = 50_000;
+const AIR_QUALITY_THRESHOLD: u16 = 480;
+const AIR_QUALITY_THRESHOLD_LOWER: u16 = 400;
 
 #[rtic::app(device = hal::pac, peripherals = true)]
 mod app {
 
-    const DISPLAY_UPDATE_INT_TICKS: u32 = 500_000;
-    const SENSOR_READ_INT_TICKS: u32 = 50_000;
-
     use super::*;
     type DisplayI2C = hal::I2C<
         I2C1,
@@ -80,6 +82,7 @@ mod app {
         adc: Adc,
         adc_pin: Pin<hal::gpio::bank0::Gpio29, hal::gpio::FloatingInput>,
         watchdog: hal::Watchdog,
+        use_lower_limit: bool,
     }
 
     #[init()]
@@ -157,6 +160,7 @@ mod app {
                 adc,
                 adc_pin,
                 watchdog,
+                use_lower_limit: false,
             },
             init::Monotonics(),
         )
@@ -210,16 +214,27 @@ mod app {
         });
     }
 
-    #[task(binds = TIMER_IRQ_1, priority = 2, shared = [alarm1, sensor_value, led], local = [adc, adc_pin, watchdog])]
+    #[task(binds = TIMER_IRQ_1, priority = 2, shared = [alarm1, sensor_value, led], local = [adc, adc_pin, watchdog, use_lower_limit])]
     fn read_sensor(mut c: read_sensor::Context) {
         let mut sensor_value: u16 = c.local.adc.read(c.local.adc_pin).unwrap();
         sensor_value = c.shared.sensor_value.lock(|v| {
             *v = (*v * (MVG_AVG_COUNT - 1) + sensor_value) / MVG_AVG_COUNT;
             *v
         });
+
+        if sensor_value >= AIR_QUALITY_THRESHOLD {
+            *c.local.use_lower_limit = true;
+        } else if sensor_value < AIR_QUALITY_THRESHOLD_LOWER && *c.local.use_lower_limit {
+            *c.local.use_lower_limit = false;
+        }
+
         let color = match sensor_value {
-            0..=450 => RGB8::new(255, 0, 0),
+            0..AIR_QUALITY_THRESHOLD_LOWER => RGB8::new(255, 0, 0),
-            451.. => RGB8::new(0, 255, 0),
+            AIR_QUALITY_THRESHOLD_LOWER..AIR_QUALITY_THRESHOLD if *c.local.use_lower_limit => {
+                RGB8::new(200, 255, 0)
+            }
+            AIR_QUALITY_THRESHOLD_LOWER..AIR_QUALITY_THRESHOLD => RGB8::new(255, 0, 0),
+            AIR_QUALITY_THRESHOLD.. => RGB8::new(0, 255, 0),
         };
 
         c.shared.led.lock(|l| {