feat: add 0x06_adc_rust driver with 9 unit tests

2026-07-24 21:00:52 +02:00 · 2026-03-25 12:25:09 -04:00
parent 05ae72d0a1
commit bfb6f5541e
18 changed files with 1581 additions and 0 deletions
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+//! @file adc.rs
+//! @brief Implementation of the 12-bit ADC driver (pure-logic helpers)
+//! @author Kevin Thomas
+//! @date 2025
+//!
+//! MIT License
+//!
+//! Copyright (c) 2025 Kevin Thomas
+//!
+//! Permission is hereby granted, free of charge, to any person obtaining a copy
+//! of this software and associated documentation files (the "Software"), to deal
+//! in the Software without restriction, including without limitation the rights
+//! to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//! copies of the Software, and to permit persons to whom the Software is
+//! furnished to do so, subject to the following conditions:
+//!
+//! The above copyright notice and this permission notice shall be included in
+//! all copies or substantial portions of the Software.
+//!
+//! THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//! IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//! FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//! AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//! LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//! OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//! SOFTWARE.
+
+/// ADC reference voltage in millivolts.
+pub const ADC_VREF_MV: u32 = 3300;
+
+/// ADC full-scale value for 12-bit resolution.
+pub const ADC_FULL_SCALE: u32 = 4095;
+
+/// Convert a raw 12-bit ADC value to millivolts.
+///
+/// Scales the raw value linearly against the 3.3 V reference.
+///
+/// # Arguments
+///
+/// * `raw` - 12-bit ADC conversion result (0–4095).
+///
+/// # Returns
+///
+/// Equivalent voltage in millivolts (0–3300).
+pub fn raw_to_mv(raw: u16) -> u32 {
+    raw as u32 * ADC_VREF_MV / ADC_FULL_SCALE
+}
+
+/// Convert a raw temperature-sensor ADC value to degrees Celsius.
+///
+/// Applies the RP2350 datasheet formula:
+///   T = 27 - (V - 0.706) / 0.001721
+///
+/// # Arguments
+///
+/// * `raw` - 12-bit ADC result from the internal temperature sensor (channel 4).
+///
+/// # Returns
+///
+/// Die temperature in degrees Celsius.
+pub fn raw_to_celsius(raw: u16) -> f32 {
+    let voltage = raw as f32 * 3.3f32 / ADC_FULL_SCALE as f32;
+    27.0f32 - (voltage - 0.706f32) / 0.001721f32
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn raw_to_mv_zero() {
+        assert_eq!(raw_to_mv(0), 0);
+    }
+
+    #[test]
+    fn raw_to_mv_full_scale() {
+        assert_eq!(raw_to_mv(4095), 3300);
+    }
+
+    #[test]
+    fn raw_to_mv_half() {
+        let mv = raw_to_mv(2048);
+        assert!(mv >= 1649 && mv <= 1651);
+    }
+
+    #[test]
+    fn raw_to_mv_quarter() {
+        let mv = raw_to_mv(1024);
+        assert!(mv >= 824 && mv <= 826);
+    }
+
+    #[test]
+    fn raw_to_celsius_room_temp() {
+        let temp = raw_to_celsius(876);
+        assert!(temp > 20.0 && temp < 35.0);
+    }
+
+    #[test]
+    fn raw_to_celsius_known_voltage() {
+        let raw = (0.706f32 / 3.3f32 * ADC_FULL_SCALE as f32 + 0.5f32) as u16;
+        let temp = raw_to_celsius(raw);
+        assert!((temp - 27.0).abs() < 1.0);
+    }
+
+    #[test]
+    fn raw_to_celsius_higher_voltage() {
+        let temp_low = raw_to_celsius(1000);
+        let temp_high = raw_to_celsius(800);
+        assert!(temp_high > temp_low);
+    }
+
+    #[test]
+    fn raw_to_mv_one_count() {
+        assert_eq!(raw_to_mv(1), 0);
+    }
+
+    #[test]
+    fn raw_to_mv_ten_counts() {
+        assert_eq!(raw_to_mv(10), 8);
+    }
+}
+
+// End of file
@@ -0,0 +1,8 @@
+//! @file lib.rs
+//! @brief Library root for the ADC driver crate
+//! @author Kevin Thomas
+//! @date 2025
+
+#![no_std]
+
+pub mod adc;
@@ -0,0 +1,283 @@
+//! @file main.rs
+//! @brief ADC demonstration: potentiometer voltage + on-chip temperature
+//! @author Kevin Thomas
+//! @date 2025
+//!
+//! MIT License
+//!
+//! Copyright (c) 2025 Kevin Thomas
+//!
+//! Permission is hereby granted, free of charge, to any person obtaining a copy
+//! of this software and associated documentation files (the "Software"), to deal
+//! in the Software without restriction, including without limitation the rights
+//! to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//! copies of the Software, and to permit persons to whom the Software is
+//! furnished to do so, subject to the following conditions:
+//!
+//! The above copyright notice and this permission notice shall be included in
+//! all copies or substantial portions of the Software.
+//!
+//! THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//! IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//! FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//! AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//! LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//! OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//! SOFTWARE.
+//!
+//! -----------------------------------------------------------------------------
+//!
+//! Demonstrates 12-bit ADC using the adc driver (adc.rs). Reads ADC
+//! channel 0 (GPIO 26) and reports the voltage in millivolts alongside
+//! the on-chip temperature sensor reading every 500 ms over UART.
+//!
+//! Wiring:
+//!   GPIO26 -> Wiper of a 10 kohm potentiometer
+//!   3.3V   -> One end of the potentiometer
+//!   GND    -> Other end of the potentiometer
+
+#![no_std]
+#![no_main]
+
+#[allow(dead_code)]
+mod adc;
+
+use defmt_rtt as _;
+#[cfg(target_arch = "riscv32")]
+use panic_halt as _;
+#[cfg(target_arch = "arm")]
+use panic_probe as _;
+
+use cortex_m::prelude::_embedded_hal_adc_OneShot;
+use fugit::RateExtU32;
+use hal::entry;
+use hal::Clock;
+use hal::gpio::{FunctionNull, FunctionUart, Pin, PullDown, PullNone};
+use hal::uart::{DataBits, Enabled, StopBits, UartConfig, UartPeripheral};
+
+#[cfg(rp2350)]
+use rp235x_hal as hal;
+
+#[cfg(rp2040)]
+use rp2040_hal as hal;
+
+#[unsafe(link_section = ".boot2")]
+#[used]
+#[cfg(rp2040)]
+pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_W25Q080;
+
+#[unsafe(link_section = ".start_block")]
+#[used]
+#[cfg(rp2350)]
+pub static IMAGE_DEF: hal::block::ImageDef = hal::block::ImageDef::secure_exe();
+
+const XTAL_FREQ_HZ: u32 = 12_000_000u32;
+
+const UART_BAUD: u32 = 115_200;
+const POLL_MS: u32 = 500;
+
+type TxPin = Pin<hal::gpio::bank0::Gpio0, FunctionUart, PullNone>;
+type RxPin = Pin<hal::gpio::bank0::Gpio1, FunctionUart, PullNone>;
+type TxPinDefault = Pin<hal::gpio::bank0::Gpio0, FunctionNull, PullDown>;
+type RxPinDefault = Pin<hal::gpio::bank0::Gpio1, FunctionNull, PullDown>;
+type EnabledUart = UartPeripheral<Enabled, hal::pac::UART0, (TxPin, RxPin)>;
+
+/// Initialise system clocks and PLLs from the external 12 MHz crystal.
+///
+/// # Arguments
+///
+/// * `xosc` - XOSC peripheral singleton.
+/// * `clocks` - CLOCKS peripheral singleton.
+/// * `pll_sys` - PLL_SYS peripheral singleton.
+/// * `pll_usb` - PLL_USB peripheral singleton.
+/// * `resets` - Mutable reference to the RESETS peripheral.
+/// * `watchdog` - Mutable reference to the watchdog timer.
+///
+/// # Returns
+///
+/// Configured clocks manager.
+///
+/// # Panics
+///
+/// Panics if clock initialisation fails.
+fn init_clocks(
+    xosc: hal::pac::XOSC,
+    clocks: hal::pac::CLOCKS,
+    pll_sys: hal::pac::PLL_SYS,
+    pll_usb: hal::pac::PLL_USB,
+    resets: &mut hal::pac::RESETS,
+    watchdog: &mut hal::Watchdog,
+) -> hal::clocks::ClocksManager {
+    hal::clocks::init_clocks_and_plls(
+        XTAL_FREQ_HZ, xosc, clocks, pll_sys, pll_usb, resets, watchdog,
+    )
+    .unwrap()
+}
+
+/// Unlock the GPIO bank and return the pin set.
+///
+/// # Arguments
+///
+/// * `io_bank0` - IO_BANK0 peripheral singleton.
+/// * `pads_bank0` - PADS_BANK0 peripheral singleton.
+/// * `sio` - SIO peripheral singleton.
+/// * `resets` - Mutable reference to the RESETS peripheral.
+///
+/// # Returns
+///
+/// GPIO pin set for the entire bank.
+fn init_pins(
+    io_bank0: hal::pac::IO_BANK0,
+    pads_bank0: hal::pac::PADS_BANK0,
+    sio: hal::pac::SIO,
+    resets: &mut hal::pac::RESETS,
+) -> hal::gpio::Pins {
+    let sio = hal::Sio::new(sio);
+    hal::gpio::Pins::new(io_bank0, pads_bank0, sio.gpio_bank0, resets)
+}
+
+/// Initialise UART0 for serial output (stdio equivalent).
+///
+/// # Arguments
+///
+/// * `uart0` - PAC UART0 peripheral singleton.
+/// * `tx_pin` - GPIO pin to use as UART0 TX (GPIO 0).
+/// * `rx_pin` - GPIO pin to use as UART0 RX (GPIO 1).
+/// * `resets` - Mutable reference to the RESETS peripheral.
+/// * `clocks` - Reference to the initialised clock configuration.
+///
+/// # Returns
+///
+/// Enabled UART0 peripheral ready for blocking writes.
+///
+/// # Panics
+///
+/// Panics if the HAL cannot achieve the requested baud rate.
+fn init_uart(
+    uart0: hal::pac::UART0,
+    tx_pin: TxPinDefault,
+    rx_pin: RxPinDefault,
+    resets: &mut hal::pac::RESETS,
+    clocks: &hal::clocks::ClocksManager,
+) -> EnabledUart {
+    let pins = (
+        tx_pin.reconfigure::<FunctionUart, PullNone>(),
+        rx_pin.reconfigure::<FunctionUart, PullNone>(),
+    );
+    let cfg = UartConfig::new(UART_BAUD.Hz(), DataBits::Eight, None, StopBits::One);
+    UartPeripheral::new(uart0, pins, resets)
+        .enable(cfg, clocks.peripheral_clock.freq())
+        .unwrap()
+}
+
+/// Create a blocking delay timer from the ARM SysTick peripheral.
+///
+/// # Arguments
+///
+/// * `clocks` - Reference to the initialised clock configuration.
+///
+/// # Returns
+///
+/// Blocking delay provider.
+///
+/// # Panics
+///
+/// Panics if the cortex-m core peripherals have already been taken.
+fn init_delay(clocks: &hal::clocks::ClocksManager) -> cortex_m::delay::Delay {
+    let core = cortex_m::Peripherals::take().unwrap();
+    cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().to_Hz())
+}
+
+/// Format a millivolt value into "ADC0: NNNN mV  |  Chip temp: ".
+///
+/// # Arguments
+///
+/// * `buf` - Mutable byte slice (must be at least 48 bytes).
+/// * `mv` - Voltage in millivolts.
+/// * `temp_int` - Integer part of temperature.
+/// * `temp_frac` - Single decimal digit of temperature fraction.
+///
+/// # Returns
+///
+/// Number of bytes written into the buffer.
+fn format_adc_line(buf: &mut [u8], mv: u32, temp_int: i32, temp_frac: u8) -> usize {
+    let prefix = b"ADC0: ";
+    buf[..6].copy_from_slice(prefix);
+    let mut pos = 6;
+    let thousands = ((mv / 1000) % 10) as u8;
+    let hundreds = ((mv / 100) % 10) as u8;
+    let tens = ((mv / 10) % 10) as u8;
+    let ones = (mv % 10) as u8;
+    buf[pos] = b'0' + thousands; pos += 1;
+    buf[pos] = b'0' + hundreds; pos += 1;
+    buf[pos] = b'0' + tens; pos += 1;
+    buf[pos] = b'0' + ones; pos += 1;
+    let mid = b" mV  |  Chip temp: ";
+    buf[pos..pos + 19].copy_from_slice(mid);
+    pos += 19;
+    let abs_temp = if temp_int < 0 { -temp_int } else { temp_int } as u32;
+    if temp_int < 0 {
+        buf[pos] = b'-'; pos += 1;
+    }
+    if abs_temp >= 100 {
+        buf[pos] = b'0' + ((abs_temp / 100) % 10) as u8; pos += 1;
+    }
+    if abs_temp >= 10 {
+        buf[pos] = b'0' + ((abs_temp / 10) % 10) as u8; pos += 1;
+    }
+    buf[pos] = b'0' + (abs_temp % 10) as u8; pos += 1;
+    buf[pos] = b'.'; pos += 1;
+    buf[pos] = b'0' + temp_frac; pos += 1;
+    let suffix = b" C\r\n";
+    buf[pos..pos + 4].copy_from_slice(suffix);
+    pos += 4;
+    pos
+}
+
+/// Application entry point for the ADC voltage and temperature demo.
+///
+/// Initializes the ADC on GPIO26 channel 0 and prints readings
+/// every 500 ms over UART.
+///
+/// # Returns
+///
+/// Does not return.
+#[entry]
+fn main() -> ! {
+    let mut pac = hal::pac::Peripherals::take().unwrap();
+    let clocks = init_clocks(
+        pac.XOSC, pac.CLOCKS, pac.PLL_SYS, pac.PLL_USB, &mut pac.RESETS,
+        &mut hal::Watchdog::new(pac.WATCHDOG),
+    );
+    let pins = init_pins(pac.IO_BANK0, pac.PADS_BANK0, pac.SIO, &mut pac.RESETS);
+    let uart = init_uart(pac.UART0, pins.gpio0, pins.gpio1, &mut pac.RESETS, &clocks);
+    let mut delay = init_delay(&clocks);
+    let mut adc_hw = hal::Adc::new(pac.ADC, &mut pac.RESETS);
+    let mut adc_pin = hal::adc::AdcPin::new(pins.gpio26).unwrap();
+    let mut temp_sensor = adc_hw.take_temp_sensor().unwrap();
+    uart.write_full_blocking(b"ADC driver initialized: GPIO26 (channel 0)\r\n");
+    let mut buf = [0u8; 48];
+    loop {
+        let raw_v: u16 = adc_hw.read(&mut adc_pin).unwrap();
+        let mv = adc::raw_to_mv(raw_v);
+        let raw_t: u16 = adc_hw.read(&mut temp_sensor).unwrap();
+        let temp = adc::raw_to_celsius(raw_t);
+        let temp_int = temp as i32;
+        let temp_frac = (((temp - temp_int as f32) * 10.0) as u8).min(9);
+        let n = format_adc_line(&mut buf, mv, temp_int, temp_frac);
+        uart.write_full_blocking(&buf[..n]);
+        delay.delay_ms(POLL_MS);
+    }
+}
+
+#[unsafe(link_section = ".bi_entries")]
+#[used]
+pub static PICOTOOL_ENTRIES: [hal::binary_info::EntryAddr; 5] = [
+    hal::binary_info::rp_cargo_bin_name!(),
+    hal::binary_info::rp_cargo_version!(),
+    hal::binary_info::rp_program_description!(c"ADC Voltage and Temperature Demo"),
+    hal::binary_info::rp_cargo_homepage_url!(),
+    hal::binary_info::rp_program_build_attribute!(),
+];
+
+// End of file