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Add overheat protection

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This commit is contained in:
Rodrigo Arias Mallo 2025-10-15 21:14:19 +02:00
parent 53e3d47a04
commit 7bd0b44871
7 changed files with 2057 additions and 6 deletions
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14
barista/Makefile
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@ -9,13 +9,20 @@ PROJ=barista
BUILD=build/$(subst :,.,$(FQBN))
HEX=$(BUILD)/$(PROJ).ino.hex
SRC=barista.ino \
ntc.c \
ntc.h \
pinout.h \
overheat.c \
overheat.h
# For host test programs
CPPFLAGS=-I.
LIBS=-lm
all: $(HEX)
$(HEX): barista.ino ntc.c ntc.h pinout.h
$(HEX): $(SRC)
arduino-cli compile $(OPTS) -e --fqbn $(FQBN)
upload: $(HEX)
@ -24,11 +31,14 @@ upload: $(HEX)
serial:
picocom -b 9600 --lower-rts --lower-dtr /dev/ttyUSB0 --imap lfcrlf
test: test_ntc
test: test_ntc test_overheat
test_ntc: test/test_ntc.o ntc.o
gcc $^ -o $@ $(LIBS)
test_overheat: test/test_overheat.o overheat.o
gcc $^ -o $@ $(LIBS)
clean:
rm -f test/test_ntc.o ntc.o

36
barista/barista.ino
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@ -2,6 +2,7 @@
* SPDX-License-Identifier: GPL-3.0-or-later */
#include "ntc.h"
#include "overheat.h"
#include "pinout.h"
#include <avr/wdt.h>
@ -23,6 +24,7 @@ enum machine_state {
HOT,
BREWING,
COOLING,
PANIC_OVERHEAT,
};
//int state = SLEEPING;
@ -83,6 +85,9 @@ struct state {
struct btn btn[MAX_BTN];
enum buzz_state buzz_state;
unsigned long buzz_t0;
struct overheat overheat;
unsigned long overheat_t0;
} g_st;
int read_input(int pin)
@ -133,6 +138,8 @@ void proc_ntc(struct state *state, const struct input *input)
avg += state->ntc_array_T[i];
state->ntc_T = avg / MAX_SAMPLES;
overheat_input(&state->overheat, millis(), state->ntc_T);
}
void proc_buttons(struct state *state, const struct input *input)
@ -169,10 +176,16 @@ void proc_buttons(struct state *state, const struct input *input)
}
}
/* In PANIC_OVERHEAT state wait at least TIME_OVERHEAT_COOL and until the
* temperature goes below TIME_OVERHEAT_TEMP before doing anything. */
#define TIME_OVERHEAT_COOL 10000 /* ms */
#define TIME_OVERHEAT_TEMP 40.0 /* °C */
int red_min = 50;
int red_state = red_min;
unsigned long brewing_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 */
@ -192,6 +205,13 @@ void proc_machine(struct state *st)
Serial.print(temp);
Serial.println(" C");
/* If the machine is overheating */
if (overheat_panic(&st->overheat)) {
st->mstate = PANIC_OVERHEAT;
st->overheat_t0 = millis();
Serial.println("PANIC OVERHEATING");
}
/* Pressing ON cancels any operation */
if (st->mstate != SLEEPING && on) {
st->mstate = SLEEPING;
@ -238,6 +258,13 @@ void proc_machine(struct state *st)
st->heating_t0 = millis();
Serial.println("heating");
}
} else if (st->mstate == PANIC_OVERHEAT) {
/* Wait until it cools down and enough time has passed */
if (st->ntc_T < TIME_OVERHEAT_TEMP &&
millis() - st->overheat_t0 > TIME_OVERHEAT_COOL) {
st->mstate = SLEEPING;
Serial.println("sleeping");
}
}
}
@ -278,18 +305,21 @@ output_leds(const struct state *st)
if (r >= 255)
r = 0;
else
r += 3;
r += 5;
} else if (st->mstate == HOT) {
setled(PIN_LED_RED, 0);
setled(PIN_LED_GREEN, 1);
r = 0;
} else if (st->mstate == PANIC_OVERHEAT) {
setled(PIN_LED_RED, 1);
setled(PIN_LED_GREEN, 0);
} else if (st->mstate == BREWING) {
setled(PIN_LED_RED, 0);
analogWrite(PIN_LED_GREEN, g);
if (g >= 255)
g = 0;
else
g += 3;
g += 5;
} else {
setled(PIN_LED_RED, 0);
setled(PIN_LED_GREEN, 0);
@ -343,6 +373,8 @@ void setup()
relay(PIN_HEAT, OFF);
relay(PIN_PUMP, OFF);
overheat_init(&g_st.overheat);
Serial.println("Ready");
wdt_enable(WDTO_250MS);
}

1886
barista/data/dry-heat-50-C.csv Normal file
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File diff suppressed because it is too large Load Diff

52
barista/overheat.c Normal file
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@ -0,0 +1,52 @@
/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
* SPDX-License-Identifier: GPL-3.0-or-later */
#include "overheat.h"
#include <string.h>
void
overheat_init(struct overheat *o)
{
memset(o, 0, sizeof(struct overheat));
}
void
overheat_input(struct overheat *o, unsigned long t_ms, float temp)
{
unsigned long delta = t_ms - o->last_time;
if (delta < OVH_INTERVAL)
return;
o->temp[o->next++] = temp;
if (o->next >= OVH_NSAMPLES)
o->next = 0;
if (o->n < OVH_NSAMPLES)
o->n++;
/* 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
overheat_delta(struct overheat *o)
{
return o->delta;
}
int
overheat_panic(struct overheat *o)
{
if (o->delta > OVH_THRESHOLD)
return 1;
else
return 0;
}

32
barista/overheat.h Normal file
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@ -0,0 +1,32 @@
/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
* SPDX-License-Identifier: GPL-3.0-or-later */
#ifndef BARISTA_OVERHEAT_H
#define BARISTA_OVERHEAT_H
#ifdef __cplusplus
extern "C" {
#endif
#define OVH_NSAMPLES 20
#define OVH_INTERVAL 200 /* ms */
#define OVH_THRESHOLD 2.0 /* °C */
struct overheat {
unsigned long last_time;
float temp[OVH_NSAMPLES];
int next;
int n;
float delta;
};
void overheat_init(struct overheat *o);
void overheat_input(struct overheat *o, unsigned long t_ms, float temp);
float overheat_delta(struct overheat *o);
int overheat_panic(struct overheat *o);
#ifdef __cplusplus
}
#endif
#endif /* BARISTA_OVERHEAT_H */

3
barista/test/test_ntc.c
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@ -1,3 +1,6 @@
/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
* SPDX-License-Identifier: GPL-3.0-or-later */
#include <stdio.h>
#include "ntc.h"

36
barista/test/test_overheat.c Normal file
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@ -0,0 +1,36 @@
/* Copyright (c) 2025 Rodrigo Arias Mallo <rodarima@gmail.com>
* SPDX-License-Identifier: GPL-3.0-or-later */
#include <stdio.h>
#include "overheat.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;
overheat_init(&ovh);
while (scanf("%f %d %f", &t, &st, &temp) == 3) {
overheat_input(&ovh, t * 1000.0, temp);
float delta = overheat_delta(&ovh);
int panic = overheat_panic(&ovh);
printf("%.3f %d %.2f %.1f %s\n", t, st, temp, delta, panic ? "PANIC" : "OK");
}
return 0;
}