README.md

@@ -125,9 +125,10 @@ formatted as line-delimited JSON.
 | `dfu`                            | Reset device and enters USB device firmware update (DFU) mode                 |
 | `ipv4 <X.X.X.X/L> [Y.Y.Y.Y]`     | Configure IPv4 address, netmask length, and optional default gateway          |
 | `fan`                            | Show current fan settings and sensors' measurements                           |
-| `fan <value>`                    | Set fan power with values from 0 to 100, where 0 is auto mode                 |
+| `fan <value>`                    | Set fan power with values from 1 to 100                                       |
+| `fan auto`                       | Enable automatic fan speed control                                            |
 | `fcurve <a> <b> <c>`             | Set fan controller curve coefficients (see *Fan control* section)             |
-| `fcurve-restore`                 | Set fan controller curve coefficients to defaults (see *Fan control* section) |
+| `fcurve default`                 | Set fan controller curve coefficients to defaults (see *Fan control* section) |
 
 
 ## USB
@@ -277,13 +278,11 @@ The thermostat implements a PID control loop for each of the TEC channels, more
 ## Fan control
 
 Fan control is available for the thermostat revisions with integrated fan system. For this purpose four commands are available:
-1. `fan` - show fan stats: `fan_pwm`, `tacho`, `abs_max_tec_i`, `auto_mode`. Please note that `tacho` shows *approximate* value, which
-linearly correlates with the actual fan speed.
-2. `fan <value>` - set the fan power with the value from `0` to `100`. Since there is no hardware way to disable the fan,
-`0` value is used for enabling automatic fan control mode, which correlates with the square of the TEC's current. 
-Values from `1` to `100` are used for setting the power from minimum to maximum respectively.
+1. `fan` - show fan stats: `fan_pwm`, `abs_max_tec_i`, `auto_mode`, `k_a`, `k_b`, `k_c`.
+2. `fan auto` - enable auto speed controller mode, which correlates with the square of the TEC's current.
+3. `fan <value>` - set the fan power with the value from `1` to `100` and disable auto mode. There is no way to disable the fan.
 Please note that power doesn't correlate with the actual speed linearly.
-3. `fcurve <a> <b> <c>` - set coefficients of the controlling curve `a*x^2 + b*x + c`, where `x` is `abs_max_tec_i/MAX_TEC_I`, 
+4. `fcurve <a> <b> <c>` - set coefficients of the controlling curve `a*x^2 + b*x + c`, where `x` is `abs_max_tec_i/MAX_TEC_I`, 
 i.e. receives values from 0 to 1 linearly tied to the maximum current. The controlling curve should produce values from 0 to 1,
 as below and beyond values would be substituted by 0 and 1 respectively.
-4. `fcurve-restore` - restore fan settings to defaults: `auto = true, a = 1.0, b = 0.0, c = 0.00`.
+5. `fcurve default` - restore fan curve settings to defaults: `a = 1.0, b = 0.0, c = 0.0`.

src/command_handler.rs

@@ -342,7 +342,7 @@ impl Handler {
         Ok(Handler::Reset)
     }
 
-    fn fan(socket: &mut TcpSocket, fan_pwm: u32, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
+    fn set_fan(socket: &mut TcpSocket, fan_pwm: u32, fan_ctrl: &mut FanCtrl) -> Result<Handler, Error> {
         fan_ctrl.set_auto_mode(false);
         fan_ctrl.set_pwm(fan_pwm);
         send_line(socket, b"{}");
@@ -404,7 +404,7 @@ impl Handler {
             Command::Ipv4(config) => Handler::set_ipv4(socket, store, config),
             Command::Reset => Handler::reset(&mut fan_ctrl.channels),
             Command::Dfu => Handler::dfu(&mut fan_ctrl.channels),
-            Command::FanSet {fan_pwm} => Handler::fan(socket, fan_pwm, fan_ctrl),
+            Command::FanSet {fan_pwm} => Handler::set_fan(socket, fan_pwm, fan_ctrl),
             Command::ShowFan => Handler::show_fan(socket, fan_ctrl),
             Command::FanAuto => Handler::fan_auto(socket, fan_ctrl),
             Command::FanCurve { k_a, k_b, k_c } => Handler::fan_curve(socket, fan_ctrl, k_a, k_b, k_c),

src/fan_ctrl.rs

@@ -2,23 +2,14 @@ use serde::Serialize;
 use stm32f4xx_hal::{
     pwm::{self, PwmChannels},
     pac::TIM8,
-    gpio::{
-        Floating, Input, ExtiPin,
-        gpioc::PC8, Edge,
-    },
-    stm32::EXTI,
-    syscfg::{SysCfg},
 };
-use smoltcp::time::Instant;
 
 use crate::{
     pins::HWRevPins,
     channels::{Channels, JsonBuffer},
-    timer
 };
 
 pub type FanPin = PwmChannels<TIM8, pwm::C4>;
-pub type TachoPin = PC8<Input<Floating>>;
 
 // as stated in the schematics
 const MAX_TEC_I: f64 = 3.0;
@@ -26,27 +17,13 @@ const MAX_TEC_I: f64 = 3.0;
 const MAX_USER_FAN_PWM: f64 = 100.0;
 const MIN_USER_FAN_PWM: f64 = 1.0;
 const MAX_FAN_PWM: f64 = 1.0;
-// below this value, motor pulse signal is too weak to be registered by tachometer
+// below this value, motor pulse signal is too weak
 const MIN_FAN_PWM: f64 = 0.05;
 
-const TACHO_MEASURE_MS: i64 = 2500;
-// by default up to 2 cycles are skipped on changes in PWM output,
-// and the halt threshold will help detect the failure during these skipped cycles
-const TACHO_HALT_THRESHOLD: u32 = 250;
-const TACHO_SKIP_CYCLES: u8 = 2;
-
 const DEFAULT_K_A: f64 = 1.0;
 const DEFAULT_K_B: f64 = 0.0;
 const DEFAULT_K_C: f64 = 0.0;
 
-// This regression is from 6% to 25% lower than values registered in the experiments.
-// Actual values would be better estimated by logarithmic regression, but that would require more
-// runtime computation, and wouldn't give significant correlation difference
-// (0.996 for log and 0.966 for quadratic regression).
-const TACHO_REGRESSION_A: f64 = -0.04135128436;
-const TACHO_REGRESSION_B: f64 = 6.23015531;
-const TACHO_REGRESSION_C: f64 = 403.6833577;
-
 
 #[derive(Serialize, Copy, Clone)]
 pub struct HWRev {
@@ -54,83 +31,46 @@ pub struct HWRev {
     pub minor: u8,
 }
 
-#[derive(Serialize, Clone, Copy, PartialEq)]
-pub enum FanStatus {
-    OK,
-    NotAvailable,
-    TooSlow,
-    Halted
-}
-
-struct TachoCtrl {
-    tacho: TachoPin,
-    tacho_cnt: u32,
-    tacho_value: Option<u32>,
-    prev_epoch: i64,
-}
-
 pub struct FanCtrl {
     fan: FanPin,
-    tacho: TachoCtrl,
     fan_auto: bool,
     available: bool,
     k_a: f64,
     k_b: f64,
     k_c: f64,
     pub channels: Channels,
-    last_status: FanStatus,
-    skip_cycles: u8,
 }
 
 impl FanCtrl {
-    pub fn new(mut fan: FanPin, tacho: TachoPin, channels: Channels, exti: &mut EXTI, syscfg: &mut SysCfg) -> Self {
+    pub fn new(mut fan: FanPin, channels: Channels) -> Self {
         let available = channels.hwrev.fan_available();
 
-        let mut tacho_ctrl = TachoCtrl::new(tacho);
         if available {
             fan.set_duty(0);
             fan.enable();
-            tacho_ctrl.init(exti, syscfg);
         }
 
         FanCtrl {
             fan,
-            tacho: tacho_ctrl,
             available,
             fan_auto: true,
             k_a: DEFAULT_K_A,
             k_b: DEFAULT_K_B,
             k_c: DEFAULT_K_C,
             channels,
-            last_status: if available { FanStatus::OK } else { FanStatus::NotAvailable },
-            skip_cycles: 0
         }
     }
 
-    pub fn cycle(&mut self) -> Result<(), FanStatus> {
-        if self.available {
-            if self.tacho.cycle() {
-                self.skip_cycles >>= 1;
-            }
-        }
+    pub fn cycle(&mut self) {
         self.adjust_speed();
-        let diagnose = self.diagnose();
-        if (self.skip_cycles == 0 || diagnose == FanStatus::Halted) && diagnose != self.last_status {
-            self.last_status = diagnose;
-            Err(diagnose)
-        } else {
-            Ok(())
-        }
     }
 
     pub fn summary(&mut self) -> Result<JsonBuffer, serde_json_core::ser::Error> {
         if self.available {
             let summary = FanSummary {
                 fan_pwm: self.get_pwm(),
-                tacho: self.tacho.get(),
                 abs_max_tec_i: self.channels.current_abs_max_tec_i(),
                 auto_mode: self.fan_auto,
-                status: self.diagnose(),
                 k_a: self.k_a,
                 k_b: self.k_b,
                 k_c: self.k_c,
@@ -165,15 +105,11 @@ impl FanCtrl {
 
     #[inline]
     pub fn restore_defaults(&mut self) {
-        self.set_auto_mode(true);
         self.set_curve(DEFAULT_K_A, DEFAULT_K_B, DEFAULT_K_C);
     }
 
     pub fn set_pwm(&mut self, fan_pwm: u32) -> f64 {
         let fan_pwm = fan_pwm.min(MAX_USER_FAN_PWM as u32).max(MIN_USER_FAN_PWM as u32);
-        self.skip_cycles = if (self.tacho.get() as f64) <= Self::threshold_for_pwm(fan_pwm as f64) {
-            TACHO_SKIP_CYCLES
-        } else { self.skip_cycles };
         let duty = Self::scale_number(fan_pwm as f64, MIN_FAN_PWM, MAX_FAN_PWM, MIN_USER_FAN_PWM, MAX_USER_FAN_PWM);
         let max = self.fan.get_max_duty();
         let value = ((duty * (max as f64)) as u16).min(max);
@@ -181,31 +117,11 @@ impl FanCtrl {
         value as f64 / (max as f64)
     }
 
-    #[inline]
-    fn threshold_for_pwm(fan_pwm: f64) -> f64 {
-        (TACHO_REGRESSION_A * fan_pwm + TACHO_REGRESSION_B) * fan_pwm + TACHO_REGRESSION_C
-    }
-
     #[inline]
     fn scale_number(unscaled: f64, to_min: f64, to_max: f64, from_min: f64, from_max: f64) -> f64 {
         (to_max - to_min) * (unscaled - from_min) / (from_max - from_min) + to_min
     }
 
-    fn diagnose(&mut self) -> FanStatus {
-        if !self.available {
-            return FanStatus::NotAvailable;
-        }
-        let threshold = Self::threshold_for_pwm(self.get_pwm() as f64) as u32;
-        let tacho = self.tacho.get();
-        if tacho >= threshold {
-            FanStatus::OK
-        } else if tacho >= TACHO_HALT_THRESHOLD {
-            FanStatus::TooSlow
-        } else {
-            FanStatus::Halted
-        }
-    }
-
     fn get_pwm(&self) -> u32 {
         let duty = self.fan.get_duty();
         let max = self.fan.get_max_duty();
@@ -213,53 +129,6 @@ impl FanCtrl {
     }
 }
 
-impl TachoCtrl {
-    fn new(tacho: TachoPin) -> Self {
-        TachoCtrl {
-            tacho,
-            tacho_cnt: 0,
-            tacho_value: None,
-            prev_epoch: 0,
-        }
-    }
-
-    fn init(&mut self, exti: &mut EXTI, syscfg: &mut SysCfg) {
-        // These lines do not cause NVIC to run the ISR,
-        // since the interrupt is masked in the cortex_m::peripheral::NVIC.
-        // Also using interrupt-related workaround is the best
-        // option for the current version of stm32f4xx-hal,
-        // since tying the IC's PC8 with the PWM's PC9 to the same TIM8 is not supported.
-        // The possible solution would be to update the library to >=v0.14.*,
-        // and use its Timer's counter functionality.
-        self.tacho.make_interrupt_source(syscfg);
-        self.tacho.trigger_on_edge(exti, Edge::Rising);
-        self.tacho.enable_interrupt(exti);
-    }
-
-    // returns whether the epoch elapsed
-    fn cycle(&mut self) -> bool {
-        let tacho_input = self.tacho.check_interrupt();
-        if tacho_input {
-            self.tacho.clear_interrupt_pending_bit();
-            self.tacho_cnt += 1;
-        }
-
-        let instant = Instant::from_millis(i64::from(timer::now()));
-        if instant.millis - self.prev_epoch >= TACHO_MEASURE_MS {
-            self.tacho_value = Some(self.tacho_cnt);
-            self.tacho_cnt = 0;
-            self.prev_epoch = instant.millis;
-            true
-        } else {
-            false
-        }
-    }
-
-    fn get(&self) -> u32 {
-        self.tacho_value.unwrap_or(u32::MAX)
-    }
-}
-
 impl HWRev {
     pub fn detect_hw_rev(hwrev_pins: &HWRevPins) -> Self {
         let (h0, h1, h2, h3) = (hwrev_pins.hwrev0.is_high(), hwrev_pins.hwrev1.is_high(),
@@ -280,26 +149,13 @@ impl HWRev {
 #[derive(Serialize)]
 pub struct FanSummary {
     fan_pwm: u32,
-    tacho: u32,
     abs_max_tec_i: f64,
     auto_mode: bool,
-    status: FanStatus,
     k_a: f64,
     k_b: f64,
     k_c: f64,
 }
 
-impl FanStatus {
-    pub fn fmt_u8(&self) -> &'static [u8] {
-        match *self {
-            FanStatus::OK => "Fan is OK".as_bytes(),
-            FanStatus::NotAvailable => "Fan is not available".as_bytes(),
-            FanStatus::TooSlow => "Fan is too slow".as_bytes(),
-            FanStatus::Halted => "Fan is halted".as_bytes(),
-        }
-    }
-}
-
 #[cfg(test)]
 mod test {
     use super::*;

src/main.rs

@@ -18,7 +18,6 @@ use stm32f4xx_hal::{
     stm32::{CorePeripherals, Peripherals, SCB},
     time::{U32Ext, MegaHertz},
     watchdog::IndependentWatchdog,
-    syscfg::SysCfgExt
 };
 use smoltcp::{
     time::Instant,
@@ -104,7 +103,7 @@ fn main() -> ! {
     cp.SCB.enable_icache();
     cp.SCB.enable_dcache(&mut cp.CPUID);
 
-    let mut dp = Peripherals::take().unwrap();
+    let dp = Peripherals::take().unwrap();
     let clocks = dp.RCC.constrain()
         .cfgr
         .use_hse(HSE)
@@ -120,7 +119,7 @@ fn main() -> ! {
 
     timer::setup(cp.SYST, clocks);
 
-    let (pins, mut leds, mut eeprom, eth_pins, usb, fan, tacho) = Pins::setup(
+    let (pins, mut leds, mut eeprom, eth_pins, usb, fan) = Pins::setup(
         clocks, dp.TIM1, dp.TIM3, dp.TIM8,
         dp.GPIOA, dp.GPIOB, dp.GPIOC, dp.GPIOD, dp.GPIOE, dp.GPIOF, dp.GPIOG,
         dp.I2C1,
@@ -151,7 +150,7 @@ fn main() -> ! {
         }
     }
 
-    let mut fan_ctrl = FanCtrl::new(fan, tacho, channels, &mut dp.EXTI, &mut dp.SYSCFG.constrain());
+    let mut fan_ctrl = FanCtrl::new(fan, channels);
 
     // default net config:
     let mut ipv4_config = Ipv4Config {
@@ -186,7 +185,7 @@ fn main() -> ! {
                     server.for_each(|_, session| session.set_report_pending(channel.into()));
                 }
 
-                let fan_status = fan_ctrl.cycle();
+                fan_ctrl.cycle();
 
                 let instant = Instant::from_millis(i64::from(timer::now()));
                 cortex_m::interrupt::free(net::clear_pending);
@@ -239,12 +238,6 @@ fn main() -> ! {
                                     }
                                 }
                             }
-                            match fan_status {
-                                Ok(_) => {}
-                                Err(status) => {
-                                    send_line(&mut socket, status.fmt_u8());
-                                }
-                            };
                         }
                     });
                 } else {

src/pins.rs

@@ -33,7 +33,7 @@ use stm32_eth::EthPins;
 use crate::{
     channel::{Channel0, Channel1},
     leds::Leds,
-    fan_ctrl::{TachoPin, FanPin}
+    fan_ctrl::FanPin
 };
 
 const PWM_FREQ: KiloHertz = KiloHertz(20u32);
@@ -131,7 +131,7 @@ impl Pins {
         spi2: SPI2, spi4: SPI4, spi5: SPI5,
         adc1: ADC1,
         otg_fs_global: OTG_FS_GLOBAL, otg_fs_device: OTG_FS_DEVICE, otg_fs_pwrclk: OTG_FS_PWRCLK,
-    ) -> (Self, Leds, Eeprom, EthernetPins, USB, FanPin, TachoPin) {
+    ) -> (Self, Leds, Eeprom, EthernetPins, USB, FanPin) {
         let gpioa = gpioa.split();
         let gpiob = gpiob.split();
         let gpioc = gpioc.split();
@@ -228,9 +228,9 @@ impl Pins {
             hclk: clocks.hclk(),
         };
 
-        let fan = Timer::new(tim8, &clocks).pwm(gpioc.pc9.into_alternate(), 20u32.khz());
+        let fan = Timer::new(tim8, &clocks).pwm(gpioc.pc9.into_alternate(), PWM_FREQ);
 
-        (pins, leds, eeprom, eth_pins, usb, fan, gpioc.pc8)
+        (pins, leds, eeprom, eth_pins, usb, fan)
     }
 
     /// Configure the GPIO pins for SPI operation, and initialize SPI
@@ -342,7 +342,7 @@ impl PwmPins {
         PwmPins {
             max_v0, max_v1,
             max_i_pos0, max_i_pos1,
-            max_i_neg0, max_i_neg1
+            max_i_neg0, max_i_neg1,
         }
     }
 }