lcd now displays the temperature.

Cargo.toml

@@ -5,7 +5,7 @@ version = "0.1.0"
 license = "MIT OR Apache-2.0"
 
 [dependencies]
-cortex-m = "0.7"
+cortex-m = {version = "0.7"}
 cortex-m-rt = "0.7"
 embedded-hal = { version = "0.2.5", features = ["unproven"] }
 
@@ -17,6 +17,7 @@ panic-probe = { version = "0.3", features = ["print-defmt"] }
 rp-pico = "0.8"
 max31855 = "0.1.0"
 hd44780-driver = "0.4.0"
+embedded-alloc = "0.5.1"
 
 # cargo build/run
 [profile.dev]

src/main.rs

@@ -1,6 +1,8 @@
 #![no_std]
 #![no_main]
 
+extern crate alloc;
+use alloc::format;
 use bsp::{
     entry,
     hal::{
@@ -9,7 +11,9 @@ use bsp::{
     },
 };
 use core::fmt::Write;
+use cortex_m::delay::Delay;
 use defmt_rtt as _;
+use embedded_alloc::Heap;
 use embedded_hal::digital::v2::OutputPin;
 use embedded_hal::spi::MODE_0;
 use panic_probe as _;
@@ -30,6 +34,19 @@ use bsp::hal::{
 use hd44780_driver as hd44780;
 use max31855::{Max31855, Unit};
 
+#[global_allocator]
+static HEAP: Heap = Heap::empty();
+
+fn write_lcd<T: hd44780_driver::bus::DataBus>(
+    lcd: &mut hd44780::HD44780<T>,
+    delay: &mut Delay,
+    string: &str,
+) {
+    lcd.reset(delay).unwrap();
+    lcd.clear(delay).unwrap();
+    lcd.write_str(string, delay).unwrap();
+}
+
 #[entry]
 fn main() -> ! {
     let mut pac = pac::Peripherals::take().unwrap();
@@ -51,6 +68,14 @@ fn main() -> ! {
     .ok()
     .unwrap();
 
+    //initalize the heap
+    {
+        use core::mem::MaybeUninit;
+        const HEAP_SIZE: usize = 1024;
+        static mut HEAP_MEM: [MaybeUninit<u8>; HEAP_SIZE] = [MaybeUninit::uninit(); HEAP_SIZE];
+        unsafe { HEAP.init(HEAP_MEM.as_ptr() as usize, HEAP_SIZE) }
+    }
+
     let mut delay = cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().to_Hz());
 
     let pins = bsp::Pins::new(
@@ -100,18 +125,16 @@ fn main() -> ! {
 
     let mut lcd = hd44780::HD44780::new_4bit(
         pins.gpio16.into_push_pull_output(), //rs
-        pins.gpio17.into_push_pull_output(), // enable
+        pins.gpio17.into_push_pull_output(), //enable
         pins.gpio18.into_push_pull_output(), //d4
         pins.gpio19.into_push_pull_output(), //d5
         pins.gpio20.into_push_pull_output(), //d6
         pins.gpio21.into_push_pull_output(), //d6
         &mut delay,
-    ).unwrap();
-
-    lcd.reset(&mut delay).unwrap();
-    lcd.clear(&mut delay).unwrap();
-    lcd.write_str("lcd initalized", &mut delay).unwrap();
+    )
+    .unwrap();
 
+    write_lcd(&mut lcd, &mut delay, "Starting");
     loop {
         led_pin.set_high().unwrap();
         external_led_pin.set_low().unwrap();
@@ -120,7 +143,10 @@ fn main() -> ! {
         external_led_pin.set_high().unwrap();
         delay.delay_ms(500);
         match spi.read_thermocouple(&mut thermometer_spi_csn, Unit::Celsius) {
-            Ok(v) => writeln!(uart, "Temp: {} \r", v).unwrap(),
+            Ok(v) => {
+                writeln!(uart, "Current: {} \r", v).unwrap();
+                write_lcd(&mut lcd, &mut delay, &format!("{:02.2} C", v))
+            }
             Err(e) => defmt::error!("error reading temp {}", defmt::Debug2Format(&e)),
         };
     }