Drawing CO2, temp. & RH to the screen

Cargo.lock

@@ -869,6 +869,7 @@ dependencies = [
  "embassy-sync",
  "embassy-time",
  "embedded-graphics",
+ "heapless",
  "rtt-target",
  "scd4x",
  "ssd1351",

Cargo.toml

@@ -38,6 +38,9 @@ scd4x = { git = "https://github.com/twokilohertz/scd4x-rs.git", branch = "conver
 ssd1351 = "0.5.0"
 display-interface-spi = "0.5.0"
 
+# Extra
+heapless = "0.8.0"
+
 [profile.dev]
 opt-level = "s"
 

src/display_task.rs

@@ -13,17 +13,15 @@ use ssd1351::{
 
 // Graphics
 use embedded_graphics::{
-    mono_font::{
+    mono_font::{ascii::FONT_6X10, MonoTextStyle},
-        ascii::{FONT_5X7, FONT_6X10},
-        MonoTextStyle,
-    },
     pixelcolor::Rgb565,
-    prelude::{Dimensions, Point, RgbColor},
+    prelude::{Point, WebColors},
     text::{Alignment, Text},
     Drawable,
 };
 
-use crate::Spi0BusMutex;
+use crate::{Spi0BusMutex, SENSOR_DATA_SIGNAL};
+use core::fmt::Write;
 
 /// Output to the SSD1351 display
 #[embassy_executor::task]
@@ -48,26 +46,55 @@ pub async fn display_output_task(
     display.reset(rst, &mut embassy_time::Delay).unwrap();
     display.init().unwrap();
 
-    let text_style1 = MonoTextStyle::new(&FONT_6X10, Rgb565::WHITE);
+    let co2_text_style = MonoTextStyle::new(&FONT_6X10, Rgb565::CSS_DARK_GREEN);
-    let text_style2 = MonoTextStyle::new(&FONT_5X7, Rgb565::WHITE);
+    let temp_text_style = MonoTextStyle::new(&FONT_6X10, Rgb565::CSS_ORANGE);
-    let text1 = "Hello, World!";
+    let humidity_text_style = MonoTextStyle::new(&FONT_6X10, Rgb565::CSS_AQUA);
-    let text2 = "2khz.xyz";
 
+    let mut co2_text_buf = heapless::String::<16>::new();
+    let mut temp_text_buf = heapless::String::<16>::new();
+    let mut humidity_text_buf = heapless::String::<16>::new();
+
+    loop {
+        // Clear contents of buffers
+        co2_text_buf.clear();
+        temp_text_buf.clear();
+        humidity_text_buf.clear();
+
+        // Wait on sensor data & format into the buffers
+        let data = SENSOR_DATA_SIGNAL.wait().await;
+        write!(&mut co2_text_buf, "CO2: {} ppm", data.co2).unwrap();
+        write!(&mut temp_text_buf, "Temp: {:.1} C", data.temperature).unwrap();
+        write!(&mut humidity_text_buf, "RH: {:.1} %", data.humidity).unwrap();
+
+        // Clear the display
+        display.clear();
+
+        // Draw the text to the screen
         Text::with_alignment(
-        text1,
+            &co2_text_buf,
-        display.bounding_box().center() + Point::new(0, -6),
+            Point::new(1, 12),
-        text_style1,
+            co2_text_style,
-        Alignment::Center,
+            Alignment::Left,
         )
         .draw(&mut display)
         .unwrap();
 
         Text::with_alignment(
-        text2,
+            &temp_text_buf,
-        display.bounding_box().center() + Point::new(0, 6),
+            Point::new(1, 24),
-        text_style2,
+            temp_text_style,
-        Alignment::Center,
+            Alignment::Left,
+        )
+        .draw(&mut display)
+        .unwrap();
+
+        Text::with_alignment(
+            &humidity_text_buf,
+            Point::new(1, 36),
+            humidity_text_style,
+            Alignment::Left,
         )
         .draw(&mut display)
         .unwrap();
     }
+}

src/main.rs

@@ -16,19 +16,28 @@ use embassy_rp::{
     peripherals::{I2C0, SPI0},
     spi,
 };
-use embassy_sync::blocking_mutex::{raw::NoopRawMutex, Mutex};
+use embassy_sync::{
+    blocking_mutex::{
+        raw::{CriticalSectionRawMutex, NoopRawMutex},
+        Mutex,
+    },
+    signal::Signal,
+};
 use embassy_time::Timer;
 use static_cell::StaticCell;
 
 use display_task::display_output_task;
 use sensor_task::sensor_read_task;
 
+type I2c0BusMutex = Mutex<NoopRawMutex, RefCell<i2c::I2c<'static, I2C0, i2c::Blocking>>>;
+type Spi0BusMutex = Mutex<NoopRawMutex, RefCell<spi::Spi<'static, SPI0, spi::Blocking>>>;
+
 embassy_rp::bind_interrupts!(struct Irqs {
     I2C0_IRQ => embassy_rp::i2c::InterruptHandler<embassy_rp::peripherals::I2C0>;
 });
 
-type I2c0BusMutex = Mutex<NoopRawMutex, RefCell<i2c::I2c<'static, I2C0, i2c::Blocking>>>;
+static SENSOR_DATA_SIGNAL: Signal<CriticalSectionRawMutex, scd4x::types::SensorData> =
-type Spi0BusMutex = Mutex<NoopRawMutex, RefCell<spi::Spi<'static, SPI0, spi::Blocking>>>;
+    Signal::new();
 
 /// Entrypoint
 #[embassy_executor::main]

src/sensor_task.rs

@@ -6,7 +6,7 @@ use rtt_target::rprintln;
 // Sensor
 use scd4x::Scd4x;
 
-use crate::I2c0BusMutex;
+use crate::{I2c0BusMutex, SENSOR_DATA_SIGNAL};
 
 /// Read CO2/temp./humidity data from the sensor
 #[embassy_executor::task]
@@ -41,6 +41,8 @@ pub async fn sensor_read_task(i2c_bus: &'static I2c0BusMutex) {
                     data.temperature,
                     data.humidity
                 );
+
+                SENSOR_DATA_SIGNAL.signal(data);
             }
             Err(error) => {
                 rprintln!(