Drawing CO2 graph

Cargo.lock

@@ -107,6 +107,12 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "circular-buffer"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4dacb91f972298e70fc507a2ffcaf1545807f1a36da586fb846646030adc542f"
+
 [[package]]
 name = "codespan-reporting"
 version = "0.11.1"
@@ -697,6 +703,15 @@ dependencies = [
  "either",
 ]
 
+[[package]]
+name = "itertools"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b192c782037fadd9cfa75548310488aabdbf3d2da73885b31bd0abd03351285"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "lalrpop"
 version = "0.19.12"
@@ -708,7 +723,7 @@ dependencies = [
  "diff",
  "ena",
  "is-terminal",
- "itertools",
+ "itertools 0.10.5",
  "lalrpop-util",
  "petgraph",
  "regex",
@@ -880,6 +895,7 @@ dependencies = [
 name = "pico-enviro-sensor"
 version = "0.1.0"
 dependencies = [
+ "circular-buffer",
  "cortex-m-rt",
  "display-interface-spi",
  "embassy-embedded-hal",
@@ -890,6 +906,7 @@ dependencies = [
  "embedded-graphics",
  "embedded-graphics-framebuf",
  "heapless",
+ "itertools 0.14.0",
  "rtt-target",
  "scd4x",
  "ssd1351",

Cargo.toml

@@ -43,6 +43,8 @@ display-interface-spi = "0.5.0"
 
 # Extra
 heapless = "0.8.0"
+circular-buffer = { version = "1.0.0", default-features = false }
+itertools = { version = "0.14.0", default-features = false }
 
 [profile.dev]
 opt-level = "s"

src/display_task.rs

@@ -17,14 +17,25 @@ use embedded_graphics::{
     draw_target::DrawTarget,
     mono_font::{ascii::FONT_6X10, MonoTextStyle},
     pixelcolor::Rgb565,
-    prelude::{Point, RgbColor, Size, WebColors},
-    primitives::Rectangle,
+    prelude::{Point, Primitive, RgbColor, Size, WebColors},
+    primitives::{Line, PrimitiveStyle, Rectangle},
     text::{Alignment, Text},
     Drawable,
 };
 
+// Containers
+use circular_buffer::CircularBuffer;
+use heapless::String;
+use itertools::Itertools;
+
 use crate::{Spi0BusMutex, SENSOR_DATA_SIGNAL};
-use core::fmt::Write;
+use core::{
+    fmt::Write,
+    ops::{Add, Div, Sub},
+};
+
+const DISPLAY_WIDTH: usize = 128;
+const DISPLAY_HEIGHT: usize = 128;
 
 /// Output to the SSD1351 display
 #[embassy_executor::task]
@@ -50,16 +61,23 @@ pub async fn display_output_task(
     display.init().unwrap();
 
     // Framebuffer, prevents flickering on redraw
-    let buf = [Rgb565::BLACK; 128 * 128];
-    let mut framebuf = FrameBuf::new(buf, 128, 128);
+    let buf = [Rgb565::BLACK; DISPLAY_WIDTH * DISPLAY_HEIGHT];
+    let mut framebuf = FrameBuf::new(buf, DISPLAY_WIDTH, DISPLAY_HEIGHT);
 
+    // Text styles
     let co2_text_style = MonoTextStyle::new(&FONT_6X10, Rgb565::CSS_DARK_GREEN);
     let temp_text_style = MonoTextStyle::new(&FONT_6X10, Rgb565::CSS_ORANGE);
     let humidity_text_style = MonoTextStyle::new(&FONT_6X10, Rgb565::CSS_AQUA);
 
-    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();
+    // Format string buffers
+    let mut co2_text_buf = String::<16>::new();
+    let mut temp_text_buf = String::<16>::new();
+    let mut humidity_text_buf = String::<16>::new();
+
+    // Ring buffer for storing past measurement data
+    let mut co2_samples = CircularBuffer::<60, u16>::new();
+    let mut temp_samples = CircularBuffer::<60, f32>::new();
+    let mut humidity_samples = CircularBuffer::<60, f32>::new();
 
     loop {
         // Clear the framebuffer
@@ -71,10 +89,67 @@ pub async fn display_output_task(
         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();
+        let sensor_data = SENSOR_DATA_SIGNAL.wait().await;
+        write!(&mut co2_text_buf, "CO2: {} ppm", sensor_data.co2).unwrap();
+        write!(&mut temp_text_buf, "Temp: {:.1} C", sensor_data.temperature).unwrap();
+        write!(&mut humidity_text_buf, "RH: {:.1} %", sensor_data.humidity).unwrap();
+
+        // Record samples
+        co2_samples.push_back(sensor_data.co2);
+        temp_samples.push_back(sensor_data.temperature);
+        humidity_samples.push_back(sensor_data.humidity);
+
+        let co2_min = *co2_samples.iter().min().unwrap();
+        let co2_max = *co2_samples.iter().max().unwrap();
+        let _temp_min = *temp_samples
+            .iter()
+            .reduce(|a: &f32, b: &f32| if a.le(b) { a } else { b })
+            .unwrap();
+        let _temp_max = *temp_samples
+            .iter()
+            .reduce(|a: &f32, b: &f32| if a.ge(b) { a } else { b })
+            .unwrap();
+        let _humid_min = *humidity_samples
+            .iter()
+            .reduce(|a: &f32, b: &f32| if a.le(b) { a } else { b })
+            .unwrap();
+        let _humid_max = *humidity_samples
+            .iter()
+            .reduce(|a: &f32, b: &f32| if a.ge(b) { a } else { b })
+            .unwrap();
+
+        /*
+           Note about drawing positions:
+           The embedded-graphics library follows the OpenGL convention of the
+           top-left of the image being (0, 0) with X increasing to the right
+           and Y increasing downwards.
+        */
+
+        // Draw line graphs
+
+        if co2_samples.len() >= 2 {
+            // CO2 line graph happens 4 pixels from the top, with 4 pixels either side
+
+            let mut x_pos: i32 = (DISPLAY_WIDTH - 4) as i32;
+
+            for (a, b) in co2_samples.iter().rev().tuple_windows::<(_, _)>() {
+                let co2_range = if (co2_max - co2_min) == 0 {
+                    1
+                } else {
+                    co2_max - co2_min
+                };
+
+                let a_y_pos: i32 = (4 + (((co2_max - a) * 30) / co2_range)) as i32;
+                let b_y_pos: i32 = (4 + (((co2_max - b) * 30) / co2_range)) as i32;
+
+                Line::new(Point::new(x_pos, a_y_pos), Point::new(x_pos - 2, b_y_pos))
+                    .into_styled(PrimitiveStyle::with_stroke(Rgb565::CSS_DARK_GREEN, 1))
+                    .draw(&mut framebuf)
+                    .unwrap();
+
+                x_pos -= 2;
+            }
+        }
 
         // Draw the text to the screen
         Text::with_alignment(
@@ -105,7 +180,10 @@ pub async fn display_output_task(
         .unwrap();
 
         // Draw the entire framebuffer to the display
-        let area: Rectangle = Rectangle::new(Point::new(0, 0), Size::new(128, 128));
+        let area: Rectangle = Rectangle::new(
+            Point::new(0, 0),
+            Size::new(DISPLAY_WIDTH as u32, DISPLAY_HEIGHT as u32),
+        );
         display.fill_contiguous(&area, framebuf.data).unwrap();
     }
 }