barista/.gitignore

@@ -1,4 +1,3 @@
 build/
-misc/
-*.test
+test_ntc
 *.o

barista/Makefile

@@ -16,10 +16,6 @@ SRC=barista.ino \
     overheat.c \
     overheat.h
 
-TESTS=ntc.test \
-      overheat.test \
-      led.test
-
 # For host test programs
 CPPFLAGS=-I.
 LIBS=-lm
@@ -35,15 +31,15 @@ upload: $(HEX)
 serial:
 	picocom -b 9600 --lower-rts --lower-dtr /dev/ttyUSB0 --imap lfcrlf
 
-test: ntc.test overheat.test led.test
+test: test_ntc test_overheat
 
-%.test: test/test_%.o test/compat.o %.o
+test_ntc: test/test_ntc.o ntc.o
 	gcc $^ -o $@ $(LIBS)
 
-thermostat.test: test/test_thermostat.o test/compat.o thermostat.o overheat.o heater.o
+test_overheat: test/test_overheat.o overheat.o
 	gcc $^ -o $@ $(LIBS)
 
 clean:
-	rm -f $(TESTS) test/*.o *.o
+	rm -f test/test_ntc.o ntc.o
 
 .PHONY: test all clean

barista/barista.ino

@@ -3,9 +3,6 @@
 
 #include "ntc.h"
 #include "overheat.h"
-#include "led.h"
-#include "heater.h"
-#include "thermostat.h"
 #include "pinout.h"
 #include <avr/wdt.h>
 
@@ -15,7 +12,8 @@ enum logic {
 };
 
 #define DEBOUNCE_TIME 20L /* ms */
-#define TEMP_HOT 75.0f /* C */
+#define TEMP_MIN 40.0f /* C */
+#define TEMP_MAX 50.0f /* C */
 
 #define LED_MIN_VALUE 0
 
@@ -52,6 +50,7 @@ enum buzz_state {
 	BUZZ_ACTIVE,
 };
 
+
 int button_pin[MAX_BTN] = {
 	[BTN_ON] = PIN_POWER_ON,
 	[BTN_HOT] = PIN_HOT,
@@ -91,12 +90,6 @@ struct state {
 
 	struct overheat overheat;
 	unsigned long overheat_t0;
-
-	struct led red_led;
-	struct led green_led;
-
-	struct heater heater;
-	struct thermostat thermostat;
 } g_st;
 
 int read_input(int pin)
@@ -194,20 +187,27 @@ void proc_buttons(struct state *state, const struct input *input)
 
 int red_min = 50;
 int red_state = red_min;
-unsigned long brewing_max_time =  30000UL; /*  30 seconds */
-unsigned long cooling_time     =   3000UL; /*   3 seconds */
-unsigned long overheat_time    =  10000UL; /*  10 seconds */
-unsigned long max_heating_time =  60000UL; /*  60 seconds */
-unsigned long max_idle_time    = 300000UL; /* 300 seconds */
+unsigned long brewing_max_time =  3000UL; /* 3 seconds */
+unsigned long cooling_time     =  3000UL; /* 3 seconds */
+unsigned long overheat_time    = 10000UL; /* 10 seconds */
+unsigned long max_heating_time = 60000UL; /* 60 seconds */
+unsigned long max_idle_time    = 10000UL; /* 10 seconds */
 
 void proc_machine(struct state *st)
 {
-	static unsigned long last_print_t = 0;
-
 	float temp = st->ntc_T;
 	int on = (st->btn[BTN_ON].state == RELEASED);
 	int brew_hot = (st->btn[BTN_HOT].state == PRESSED);
-	unsigned long t = millis();
+
+	Serial.print("t=");
+	Serial.print(millis());
+	Serial.print(" state=");
+	Serial.print(st->mstate);
+	Serial.print(" on=");
+	Serial.print(on);
+	Serial.print(" temp=");
+	Serial.print(temp);
+	Serial.println(" C");
 
 	/* If the machine is overheating */
 	if (overheat_panic(&st->overheat)) {
@@ -235,7 +235,7 @@ void proc_machine(struct state *st)
 			Serial.println("heating");
 		}
 	} else if (st->mstate == HEATING) {
-		if (temp > TEMP_HOT) {
+		if (temp > TEMP_MAX) {
 			st->mstate = HOT;
 			st->hot_t0 = millis();
 			st->buzz_state = BUZZ_HEY;
@@ -313,85 +313,64 @@ void do_proc(struct state *st, const struct input *input)
 void
 output_leds(const struct state *st)
 {
-	unsigned long t = millis();
+	static int r = 0;
+	static int g = 0;
 
-	if (st->mstate == SLEEPING) {
-		led_off(&st->red_led);
-		led_off(&st->green_led);
-	} else if (st->mstate == HEATING) {
-		led_off(&st->red_led);
-		led_pattern(&st->green_led, t, 1000UL, "000123456789abcdefff");
-	} else if (st->mstate == COOLING) {
-		led_off(&st->red_led);
-		led_pattern(&st->green_led, t, 1000UL, "fffedcba987654321000");
+	if (st->mstate == HEATING || st->mstate == COOLING) {
+		analogWrite(PIN_LED_RED, r);
+		setled(PIN_LED_GREEN, 0);
+		if (r >= 255)
+			r = 0;
+		else
+			r += 5;
 	} else if (st->mstate == HOT) {
-		led_off(&st->red_led);
-		led_on(&st->green_led);
+		setled(PIN_LED_RED, 0);
+		setled(PIN_LED_GREEN, 1);
+		r = 0;
 	} else if (st->mstate == PANIC_OVERHEAT) {
-		led_pattern(&st->red_led,   t, 3000UL, "f0f0f0000000");
-		led_pattern(&st->green_led, t, 3000UL, "000000f0f0f0");
+		setled(PIN_LED_RED, 1);
+		setled(PIN_LED_GREEN, 0);
 	} else if (st->mstate == BREWING_HOT || st->mstate == BREWING_COLD) {
-		led_off(&st->red_led);
-		led_pattern(&st->green_led, millis(), 2000UL, "0123456789abcdefedcba9876543210");
+		setled(PIN_LED_RED, 0);
+		analogWrite(PIN_LED_GREEN, g);
+		if (g >= 255)
+			g = 0;
+		else
+			g += 5;
 	} else {
-		led_off(&st->red_led);
-		led_off(&st->green_led);
+		setled(PIN_LED_RED, 0);
+		setled(PIN_LED_GREEN, 0);
+		r = 0;
 	}
-
-	analogWrite(PIN_LED_RED, led_level(&st->red_led, t));
-	analogWrite(PIN_LED_GREEN, led_level(&st->green_led, t));
 }
 
 void
-output_relays(const struct state *st)
+output_heater(const struct state *st)
 {
-	unsigned long t = millis();
-
-	/* First configure thermostate */
-	if (st->mstate == HEATING || st->mstate == HOT || st->mstate == BREWING_HOT)
-		thermostat_set(&st->thermostat, TEMP_HOT+5.0);
-	else
-		thermostat_off(&st->thermostat);
-
-	/* Then update heater state from thermostate */
-	float T = st->ntc_T;
-	float dT_dt = overheat_speed(&st->overheat);
-	float u = thermostat_state(&st->thermostat, T, dT_dt);
-	heater_on(&st->heater, t, u);
-
-	/* Then switch relays accordingly */
-	int heater_relay_st = heater_state(&st->heater, t);
-	if (heater_relay_st)
-		relay(PIN_HEAT, ON);
-	else
+	if (st->mstate == HEATING || st->mstate == HOT || st->mstate == BREWING_HOT) {
+		if (st->ntc_T < TEMP_MIN)
+			relay(PIN_HEAT, ON);
+		else if (st->ntc_T > TEMP_MAX)
+			relay(PIN_HEAT, OFF);
+	} else {
 		relay(PIN_HEAT, OFF);
+	}
+}
 
-	int pump_relay_st = 0;
+void
+output_pump(const struct state *st)
+{
 	if (st->mstate == BREWING_HOT || st->mstate == BREWING_COLD)
-		pump_relay_st = 1;
-
-	if (pump_relay_st)
 		relay(PIN_PUMP, ON);
 	else
 		relay(PIN_PUMP, OFF);
-
-	Serial.print(t);
-	Serial.print(" ");
-	Serial.print(st->mstate);
-	Serial.print(" ");
-	Serial.print(T);
-	Serial.print(" ");
-	Serial.print(u);
-	Serial.print(" ");
-	Serial.print(heater_relay_st);
-	Serial.print(" ");
-	Serial.println(pump_relay_st);
 }
 
 void do_output(const struct state *st)
 {
 	output_leds(st);
-	output_relays(st);
+	output_heater(st);
+	output_pump(st);
 }
 
 void setup()

barista/heater.c

@@ -1,70 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#include "heater.h"
-
-#define HEATER_MIN	 500UL /* ms */
-#define HEATER_MAX	2000UL /* ms */
-#define HEATER_PERIOD	5000UL /* ms */
-
-void
-heater_on(struct heater *h, unsigned long t_ms, float duty)
-{
-	unsigned long dt_on = duty * HEATER_MAX;
-
-	if (dt_on < HEATER_MIN)
-		dt_on = 0;
-	else if (dt_on > HEATER_MAX)
-		dt_on = HEATER_MAX;
-
-	h->next_on_dt = dt_on;
-
-	if (h->st == HEATER_OFF) {
-		h->st = HEATER_ON;
-		h->t0_on = t_ms;
-		h->t0_off = t_ms + h->next_on_dt;
-		h->cycle = CYCLE_ON;
-	}
-}
-
-void
-heater_off(struct heater *h)
-{
-	h->st = HEATER_OFF;
-}
-
-int
-heater_state(struct heater *h, unsigned long t_ms)
-{
-	if (h->st == HEATER_OFF)
-		return 0;
-
-	/* Switch state if current time exceeds time limit
-	 * in the current state */
-	/* FIXME: Integer overflow can cause the heater to turn on forever */
-	while (1) {
-		int changed = 0;
-		if (h->cycle == CYCLE_ON) {
-			if (t_ms >= h->t0_off) {
-				h->cycle = CYCLE_OFF;
-				h->t0_on += HEATER_PERIOD;
-				changed = 1;
-			}
-		} else if (h->cycle == CYCLE_OFF) {
-			if (t_ms >= h->t0_on) {
-				/* Compute current cycle t0_off */
-				h->cycle = CYCLE_ON;
-				h->t0_off = h->t0_on + h->next_on_dt;
-				changed = 1;
-			}
-		}
-
-		if (!changed)
-			break;
-	}
-
-	if (h->cycle == CYCLE_ON)
-		return 1;
-
-	return 0;
-}

barista/heater.h

@@ -1,39 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#ifndef BARISTA_HEATER_H
-#define BARISTA_HEATER_H
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-enum heater_state {
-	HEATER_OFF = 0,
-	HEATER_ON,
-};
-
-enum heater_cycle {
-	CYCLE_ON = 0,
-	CYCLE_OFF,
-};
-
-struct heater {
-	enum heater_state st;
-	enum heater_cycle cycle;
-	unsigned long t0_on; /* current cycle time on */
-	unsigned long t0_off; /* current cycle time off */
-
-	/* Next cycle */
-	unsigned long next_on_dt; /* in ms */
-};
-
-void heater_on(struct heater *h, unsigned long t_ms, float duty);
-void heater_off(struct heater *h);
-int heater_state(struct heater *h, unsigned long t_ms);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* BARISTA_HEATER_H */

barista/led.c

@@ -1,71 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#include "led.h"
-#include <string.h>
-
-void led_on(struct led *led)
-{
-	led->mode = LED_ON;
-}
-
-void led_off(struct led *led)
-{
-	led->mode = LED_OFF;
-}
-
-void led_pattern(struct led *led, unsigned long t_ms, unsigned long period_ms, const char *pattern)
-{
-	int n = strlen(pattern);
-	unsigned long step_ms = period_ms / n;
-
-	/* Don't change the current state */
-	if (led->mode == LED_PATTERN &&
-			led->step_ms == step_ms &&
-			led->pattern == pattern)
-		return;
-
-	led->mode = LED_PATTERN;
-	led->pat_i = 0;
-	led->pat_n = n;
-	led->pattern = pattern;
-	led->step_ms = step_ms;
-	led->t_ms = t_ms;
-}
-
-/* Return led level brightness in [0, 255] at current time */
-int led_level(struct led *led, unsigned long t_ms)
-{
-	if (led->mode == LED_OFF)
-		return 0;
-
-	if (led->mode == LED_ON)
-		return 255;
-
-	if (led->mode == LED_PATTERN) {
-		while (led->t_ms + led->step_ms < t_ms) {
-			led->t_ms += led->step_ms;
-			led->pat_i++;
-			if (led->pat_i >= led->pat_n)
-				led->pat_i = 0;
-		}
-
-		int c = led->pattern[led->pat_i];
-		int level;
-
-		if (c >= '0' && c <= '9')
-			level = 17 * (c - '0');
-		else
-			level = 17 * (10 + (c - 'a'));
-
-		if (level < 0)
-			level = 0;
-		else if (level > 255)
-			level = 255;
-
-		return level;
-	}
-
-	/* Unknown mode, turn off */
-	return 0;
-}

barista/led.h

@@ -1,35 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#ifndef BARISTA_LED_H
-#define BARISTA_LED_H
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-enum led_mode {
-	LED_OFF = 0,
-	LED_ON,
-	LED_PATTERN,
-};
-
-struct led {
-	enum led_mode mode;
-	const char *pattern;
-	int pat_i;
-	int pat_n;
-	unsigned long step_ms;
-	unsigned long t_ms;
-};
-
-void led_on(struct led *led);
-void led_off(struct led *led);
-void led_pattern(struct led *led, unsigned long t_ms, unsigned long period_ms, const char *pattern);
-int led_level(struct led *led, unsigned long t_ms);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* BARISTA_LED_H */

barista/overheat.c

@@ -18,25 +18,22 @@ overheat_input(struct overheat *o, unsigned long t_ms, float temp)
 	if (delta < OVH_INTERVAL)
 		return;
 
-	/* If already go n samples, recompute delta and speed */
-	if (o->n == OVH_NSAMPLES) {
-		float last_T = o->temp[o->next];
-		float last_t = o->t[o->next];
-		float dt = (float) (t_ms - last_t) * 1e-3;
-		o->delta = temp - last_T;
-		o->speed = o->delta / dt;
-	}
-
-	/* Add the new sample */
-	o->temp[o->next] = temp;
-	o->t[o->next] = t_ms;
-	o->next++;
+	o->temp[o->next++] = temp;
 	if (o->next >= OVH_NSAMPLES)
 		o->next = 0;
 	if (o->n < OVH_NSAMPLES)
 		o->n++;
 
-	o->last_time = t_ms;
+	/* Recompute state */
+	float tmin = 10000.0, tmax = 0.0;
+	for (int i = 0; i < o->n; i++) {
+		if (o->temp[i] < tmin)
+			tmin = o->temp[i];
+		if (o->temp[i] > tmax)
+			tmax = o->temp[i];
+	}
+
+	o->delta = tmax - tmin;
 }
 
 float
@@ -45,16 +42,10 @@ overheat_delta(struct overheat *o)
 	return o->delta;
 }
 
-float
-overheat_speed(struct overheat *o)
-{
-	return o->speed;
-}
-
 int
 overheat_panic(struct overheat *o)
 {
-	if (o->speed > OVH_THRESHOLD)
+	if (o->delta > OVH_THRESHOLD)
 		return 1;
 	else
 		return 0;

barista/overheat.h

@@ -10,22 +10,19 @@ extern "C" {
 
 #define OVH_NSAMPLES	20
 #define OVH_INTERVAL	200 /* ms */
-#define OVH_THRESHOLD	2.0 /* °C / s */
+#define OVH_THRESHOLD	2.0 /* °C */
 
 struct overheat {
 	unsigned long last_time;
 	float temp[OVH_NSAMPLES];
-	long unsigned t[OVH_NSAMPLES];
 	int next;
 	int n;
 	float delta;
-	float speed;
 };
 
 void overheat_init(struct overheat *o);
 void overheat_input(struct overheat *o, unsigned long t_ms, float temp);
 float overheat_delta(struct overheat *o);
-float overheat_speed(struct overheat *o);
 int overheat_panic(struct overheat *o);
 
 #ifdef __cplusplus

barista/test/compat.c

@@ -1,13 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#include "compat.h"
-#include <time.h>
-
-unsigned long millis(void)
-{
-	struct timespec ts;
-	clock_gettime(CLOCK_MONOTONIC, &ts);
-
-	return ts.tv_sec * 1000UL + ts.tv_nsec / 1000000UL;
-}

barista/test/compat.h

@@ -1,17 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#ifndef BARISTA_COMPAT_H
-#define BARISTA_COMPAT_H
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-unsigned long millis(void);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* BARISTA_COMPAT_H */

barista/test/test_led.c

@@ -1,42 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#include <stdio.h>
-#include "led.h"
-#include "compat.h"
-
-int main(void)
-{
-	struct led led;
-	unsigned long t0 = millis();
-	unsigned long step = 1000UL;
-
-	led_pattern(&led, t0, step, "000123456789abcdefff");
-
-	int last_level = -1;
-
-	unsigned long last_t = millis();
-	while (1) {
-		unsigned long t = millis();
-
-		if (t - t0 >= 10000UL)
-			break;
-
-		if (t - last_t < 50UL)
-			continue;
-
-		int level = led_level(&led, millis());
-		printf("|");
-		for (int i = 0; i < 256; i+=4) {
-			if (i < level)
-				printf("=");
-			else
-				printf(" ");
-		}
-		printf("|\n");
-		last_level = level;
-		last_t = t;
-	}
-
-	return 0;
-}

barista/test/test_thermostat.c

@@ -1,49 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#include <stdio.h>
-#include "overheat.h"
-#include "thermostat.h"
-#include "heater.h"
-
-/* Read a CSV from the stdin in the format
- * <time_in_seconds> <state> <temp_in_C>
- * skipping the first row (header).
- *
- * Outputs overheat state. */
-
-#define MAX_LINE 1024
-
-int main(void)
-{
-	char buf[MAX_LINE];
-	fgets(buf, MAX_LINE, stdin);
-
-	float t, temp;
-	int st;
-
-	struct overheat ovh = { 0 };
-	struct thermostat th = { 0 };
-	struct heater heater = { 0 };
-
-	overheat_init(&ovh);
-
-	for (int i = 0; scanf("%f %d %f", &t, &st, &temp) == 3; i++) {
-		if (i == 0)
-			thermostat_set(&th, 60.0);
-
-		unsigned long t_ms = t * 1000;
-
-		overheat_input(&ovh, t_ms, temp);
-		float delta = overheat_delta(&ovh);
-		float speed = overheat_speed(&ovh);
-		float u = thermostat_state(&th, temp, speed);
-		heater_on(&heater, t_ms, u);
-		int h = heater_state(&heater, t_ms);
-		int panic = overheat_panic(&ovh);
-
-		printf("%8.3f %2d %6.2f %6.1f %8.3f %8.3f %d %s\n", t, st, temp, delta, speed, u, h, panic ? "PANIC" : "OK");
-	}
-
-	return 0;
-}

barista/thermostat.c

@@ -1,64 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#include "thermostat.h"
-
-#define TEMP_MIN	35.0 /* °C */
-#define DELTA_LOW	1.0
-#define DELTA_HIGH	1.0
-
-#define T_ERR_MIN	35.0 /* °C */
-
-void
-thermostat_set(struct thermostat *th, float temp_target)
-{
-	if (th->st == THERMOSTAT_ON && th->temp_target == temp_target)
-		return;
-
-	th->st = THERMOSTAT_ON;
-	th->temp_target = temp_target;
-	th->temp_min = temp_target - DELTA_LOW;
-	th->temp_max = temp_target + DELTA_HIGH;
-	th->on = 1;
-}
-
-void
-thermostat_off(struct thermostat *th)
-{
-	th->st = THERMOSTAT_OFF;
-	th->on = 0;
-}
-
-static float
-pid(float T0, float T, float dT_dt)
-{
-	float err_min = 2.0;
-
-	/* The rate of change of error is the same as the temperature, as they
-	 * are only offset by a mostly constant value */
-	float derr_dt = dT_dt;
-
-	if ((T0 - T) < err_min)
-		return 0.0;
-
-	float Kp = 1.0 / 20.0;
-	float Kd = - 1.0 / 3.0;
-	float u = Kp * (T0 - T) + Kd * dT_dt;
-
-	if (u < 0.0)
-		u = 0.0;
-	else if (u > 1.0)
-		u = 1.0;
-
-	return u;
-}
-
-/* Return a value in [0, 1] to set the heater duty cycle */
-float
-thermostat_state(struct thermostat *th, float T, float dT_dt)
-{
-	if (th->st == THERMOSTAT_OFF)
-		return 0.0;
-
-	return pid(th->temp_target, T, dT_dt);
-}

barista/thermostat.h

@@ -1,32 +0,0 @@
-/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
- * SPDX-License-Identifier: GPL-3.0-or-later */
-
-#ifndef BARISTA_THERMOSTAT_H
-#define BARISTA_THERMOSTAT_H
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-enum thermostat_state {
-	THERMOSTAT_OFF = 0,
-	THERMOSTAT_ON,
-};
-
-struct thermostat {
-	enum thermostat_state st;
-	float temp_target;
-	float temp_min;
-	float temp_max;
-	int on;
-};
-
-void thermostat_set(struct thermostat *th, float temp_target);
-void thermostat_off(struct thermostat *th);
-float thermostat_state(struct thermostat *th, float T, float dT_dt);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* BARISTA_THERMOSTAT_H */