76 lines
2.5 KiB
Rust
Executable file
76 lines
2.5 KiB
Rust
Executable file
// NOTE: This is at least unreliable and likely wrong
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#![no_main]
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#![no_std]
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use defmt::{debug, info};
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use hal::adc::{Adc, Ready, VRef, VTemp};
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use hal::calibration::{VtempCal30, VtempCal130};
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use panic_probe as _;
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use defmt_rtt as _; // global logger
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use cortex_m_rt::entry;
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use hal::{pac, prelude::*, rcc::Config};
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#[entry]
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fn main() -> ! {
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let dp = pac::Peripherals::take().unwrap();
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let cp = cortex_m::Peripherals::take().unwrap();
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let mut rcc = dp.RCC.freeze(Config::hsi16());
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let mut adc: Adc<_> = dp.ADC.constrain(&mut rcc);
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let mut delay = cp.SYST.delay(rcc.clocks);
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// NOTE: TSEN bit must be enabled for reading the temperature
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VTemp.enable(&mut adc);
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VRef.enable(&mut adc);
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// reference temperatures from the chips readonly memory
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// [Source](https://www.st.com/resource/en/datasheet/stm32l053r8.pdf),
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// Table 6 in Secion 3.13 "Temperature sensor"
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//
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// More and better info in the large 1000+ page sheet "Ultra-low-power
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// STM32L0x3 advanced Arm®-based 32-bit MCUs" (RM0367), 14.9
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//
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// This is basically calibration data
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info!(
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"reading calibration data... If this is the last thing you hear from me something has gone terribly wrong"
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);
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let vref_cal = hal::calibration::VrefintCal::get().read();
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let tsense_cal1 = (30, VtempCal30::get().read());
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let tsense_cal2 = (130, VtempCal130::get().read());
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info!("tsense_cal1: {:?}", (30, tsense_cal1));
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info!("tsense_cal2: {:?}", (130, tsense_cal2));
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delay.delay_ms(50_u16);
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let vref_actual: u16 = adc.read(&mut VRef).unwrap();
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let vref_factor = vref_cal as f32 / vref_actual as f32;
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debug!(
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"vref actual={} calibration={} => factor={}",
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vref_actual, vref_cal, vref_factor
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);
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let mut temp_c;
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let mut temp_mv;
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loop {
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temp_mv = read_temp_mv(&mut adc, vref_factor);
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temp_c = temp_mv_to_c(temp_mv, tsense_cal1, tsense_cal2);
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info!("Temperature: {:03}mv, {:04}c", temp_mv, temp_c as i32);
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delay.delay_ms(500_u16);
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}
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}
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fn read_temp_mv(adc: &mut Adc<Ready>, vref_factor: f32) -> f32 {
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let bare: f32 = adc.read(&mut VTemp).expect("could not read with adc");
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bare * vref_factor
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}
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// This unholy abomination is from the datasheet and does not actually look so bad if it's written
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// in Math instead of Rust.
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fn temp_mv_to_c(temp: f32, ts_cal_1: (i32, u16), ts_cal_2: (i32, u16)) -> f32 {
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((ts_cal_2.0 as f32 - ts_cal_1.0 as f32) / (ts_cal_2.1 as f32 - ts_cal_1.1 as f32))
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* (temp - ts_cal_1.1 as f32)
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+ ts_cal_1.0 as f32
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}
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