Implement reflow process

src/main.rs

@@ -10,18 +10,23 @@ use cortex_m::delay::Delay;
 use display_interface::DisplayError;
 
 use embedded_graphics::{
-    mono_font::{iso_8859_1::FONT_6X10, MonoTextStyle},
+    mono_font::{iso_8859_1::FONT_10X20, MonoTextStyle},
     pixelcolor::BinaryColor,
     prelude::*,
-    text::{Alignment, Text},
+    text::{Alignment, Baseline, Text, TextStyleBuilder},
 };
 
-use embedded_hal::digital::v2::{InputPin, ToggleableOutputPin};
+use embedded_hal::{
+    digital::v2::{InputPin, OutputPin, ToggleableOutputPin},
+    timer::CountDown as _,
+};
 
-use fugit::RateExtU32;
+use fugit::{ExtU64, MicrosDurationU64, RateExtU32};
 
 use max6675::{Error, Max6675};
 
+use nb::Error::WouldBlock;
+
 use panic_halt as _;
 
 use rp_pico::{
@@ -30,6 +35,7 @@ use rp_pico::{
         clocks::{self, Clock},
         gpio::PinState,
         i2c::I2C,
+        timer::CountDown,
         usb::UsbBus,
         Sio, Timer, Watchdog,
     },
@@ -43,6 +49,22 @@ use usb_device::{bus::UsbBus as UsbBusTrait, bus::UsbBusAllocator, prelude::*};
 
 use usbd_serial::{SerialPort, USB_CLASS_CDC};
 
+const HYSTERESIS: u16 = 5;
+
+const PEAK_TEMPERATURE: u16 = 240;
+
+const PREHEAT_TEMPERATURE: u16 = 150;
+
+const SOAK_TIME: MicrosDurationU64 = MicrosDurationU64::secs(90);
+
+enum State<'a> {
+    Off,
+    Preheat,
+    Soak(CountDown<'a>),
+    Reflow,
+    Cooling,
+}
+
 fn print_serial<'a, B: UsbBusTrait>(
     serial: &mut SerialPort<'a, B>,
     msg: &str,
@@ -50,13 +72,18 @@ fn print_serial<'a, B: UsbBusTrait>(
     let buf = msg.as_bytes();
     let mut pos = 0;
 
+    let mut retry_count = 0;
     while pos < buf.len() {
         match serial.write(&buf[pos..]) {
             Ok(count) => {
                 pos += count;
+                retry_count = 0;
+                continue;
+            }
+            Err(UsbError::WouldBlock) if retry_count < 100 => {
+                retry_count += 1;
                 continue;
             }
-            Err(UsbError::WouldBlock) => continue,
             Err(err) => return Err(err),
         }
     }
@@ -88,6 +115,7 @@ fn stringify_display_error(err: DisplayError) -> &'static str {
 fn display_text<DI, SIZE>(
     display: &mut Ssd1306<DI, SIZE, BufferedGraphicsMode<SIZE>>,
     text: &str,
+    baseline: Baseline,
 ) -> Result<(), DisplayError>
 where
     DI: WriteOnlyDataCommand,
@@ -95,11 +123,14 @@ where
 {
     let (w, h) = display.dimensions();
 
-    Text::with_alignment(
+    Text::with_text_style(
         text,
         Point::new((w / 2).into(), (h / 2).into()),
-        MonoTextStyle::new(&FONT_6X10, BinaryColor::On),
-        Alignment::Center,
+        MonoTextStyle::new(&FONT_10X20, BinaryColor::On),
+        TextStyleBuilder::new()
+            .alignment(Alignment::Center)
+            .baseline(baseline)
+            .build(),
     )
     .draw(display)?;
 
@@ -153,9 +184,8 @@ fn main() -> ! {
         }
 
         let mut buf = [0u8];
-        match serial.read(&mut buf[..]) {
-            Ok(_) => break,
-            _ => (),
+        if let Ok(_) = serial.read(&mut buf[..]) {
+            break;
         }
     }
 
@@ -177,9 +207,8 @@ fn main() -> ! {
     )
     .into_buffered_graphics_mode();
 
-    let result = display.init().map_err(stringify_display_error);
-    if let Err(msg) = result {
-        let _ = print_serial(&mut serial, msg);
+    if let Err(err) = display.init() {
+        let _ = print_serial(&mut serial, stringify_display_error(err));
         panic!();
     }
 
@@ -195,17 +224,41 @@ fn main() -> ! {
 
     let mut led = pins.led.into_push_pull_output_in_state(PinState::Low);
 
+    let mut button_held = false;
+    let mut button_cooldown = timer.count_down();
+    button_cooldown.start(0.secs());
+
     let mut counter = 0;
+    let mut current_temperature = Option::<u16>::None;
+    let mut state = State::Off;
     loop {
         delay.delay_ms(5);
         counter = (counter + 1) % 100;
 
+        if let Ok(_) = button_cooldown.wait() {
+            let button_pressed = button.is_low().unwrap();
+            if button_pressed && !button_held {
+                state = if let State::Off = state {
+                    State::Preheat
+                } else {
+                    State::Off
+                };
+
+                button_cooldown.start(500.millis());
+            } else {
+                button_cooldown.start(0.secs());
+            }
+
+            button_held = button_pressed;
+        }
+
         if counter == 0 {
             led.toggle().unwrap();
 
             let mut bytes: [u8; 7] = [32, 32, 32, 32, 194, 176, 67];
             let text = match thermocouple.read_temperature(&mut timer.count_down()) {
                 Ok(mut temperature) => {
+                    current_temperature = Some(temperature);
                     temperature >>= 2;
 
                     for i in (0..3).rev() {
@@ -227,14 +280,65 @@ fn main() -> ! {
 
             display.clear_buffer();
 
-            if let Err(err) = display_text(&mut display, text) {
+            if let Err(err) = display_text(&mut display, text, Baseline::Bottom) {
+                let _ = println_serial(&mut serial, stringify_display_error(err));
+            }
+
+            let state_str = match state {
+                State::Off => "OFF",
+                State::Preheat => "PREHEAT",
+                State::Soak(_) => "SOAK",
+                State::Reflow => "REFLOW",
+                State::Cooling => "COOLING",
+            };
+
+            if let Err(err) = display_text(&mut display, state_str, Baseline::Top) {
                 let _ = println_serial(&mut serial, stringify_display_error(err));
             }
         }
 
-        if button.is_low().unwrap() {
-            relay.toggle().unwrap();
-            delay.delay_ms(1000);
+        if let Some(temperature) = current_temperature {
+            match state {
+                State::Off => (),
+                State::Preheat => {
+                    if temperature < PREHEAT_TEMPERATURE {
+                        relay.set_high().unwrap();
+                    } else {
+                        let mut time = timer.count_down();
+                        time.start(SOAK_TIME);
+                        state = State::Soak(time);
+                    }
+                }
+                State::Soak(ref mut time) => match time.wait() {
+                    Ok(_) => state = State::Reflow,
+                    Err(WouldBlock) => {
+                        if temperature < PREHEAT_TEMPERATURE - HYSTERESIS {
+                            relay.set_high().unwrap();
+                        } else if temperature > PREHEAT_TEMPERATURE + HYSTERESIS * 2 {
+                            state = State::Reflow;
+                        } else if temperature > PREHEAT_TEMPERATURE + HYSTERESIS {
+                            relay.set_low().unwrap();
+                        }
+                    }
+                    Err(_) => state = State::Off,
+                },
+                State::Reflow => {
+                    if temperature < PEAK_TEMPERATURE {
+                        relay.set_high().unwrap();
+                    } else {
+                        relay.set_low().unwrap();
+
+                        state = State::Cooling;
+                    }
+                }
+                State::Cooling => state = State::Off,
+            }
+        } else {
+            state = State::Off;
+        }
+
+        if let State::Off = state {
+            relay.set_low().unwrap();
         }
 
         if !usb_dev.poll(&mut [&mut serial]) {
@@ -242,11 +346,8 @@ fn main() -> ! {
         }
 
         let mut buf = [0u8; 64];
-        match serial.read(&mut buf[..]) {
-            Ok(count) => {
-                let _ = serial.write(&buf[..count]);
-            }
-            _ => (),
+        if let Ok(count) = serial.read(&mut buf[..]) {
+            let _ = serial.write(&buf[..count]);
         }
     }
 }