thermostat-hw/tools/thermostat_test.c

/*
 * Drives thermostat.c with synthetic time to prove the protections actually
 * fire. Nothing here touches hardware; time is a variable, so two hours of
 * furnace behaviour runs in milliseconds.
 *
 * This logic controls a gas valve, so it gets verified before it gets flashed:
 *
 *     gcc -Wall -Wextra -I main/control -o /tmp/therm_test \
 *         tools/thermostat_test.c main/control/thermostat.c -lm && /tmp/therm_test
 *
 * Exits non-zero on failure. Worth re-running after any edit to thermostat.c.
 */
#include <stdio.h>
#include <string.h>
#include "thermostat.h"

static therm_state_t last = (therm_state_t)-1;
static uint32_t t_ms;

static const char *sname(therm_state_t s)
{
    switch (s) {
    case THERM_STATE_OFF:       return "OFF";
    case THERM_STATE_IDLE:      return "IDLE";
    case THERM_STATE_HEATING:   return "HEATING";
    case THERM_STATE_LOCKOUT:   return "LOCKOUT";
    case THERM_STATE_NO_SENSOR: return "NO_SENSOR";
    }
    return "?";
}

/* Advance `secs` seconds at 1Hz, printing only transitions. */
static void run(float temp, int temp_valid, int secs)
{
    therm_status_t st;
    for (int i = 0; i < secs; i++) {
        t_ms += 1000;
        thermostat_tick(temp, temp_valid, t_ms);
        thermostat_get_status(&st);
        if (st.state != last) {
            char txt[32];
            thermostat_state_text(&st, txt, sizeof(txt));
            printf("  %6.1f min  %-9s heat=%d fan=%d cycles=%u  \"%s\"\n",
                   t_ms / 60000.0, sname(st.state), st.heat_relay, st.fan_relay,
                   st.cycles_last_hour, txt);
            last = st.state;
        }
    }
}

int main(void)
{
    therm_status_t st;

    printf("min_on=%us min_off=%us max_cph=%d deadband=%.1fF\n\n",
           THERM_MIN_ON_MS / 1000, THERM_MIN_OFF_MS / 1000,
           THERM_MAX_CYCLES_PER_HOUR, THERM_DEADBAND_F);

    thermostat_init(0);
    thermostat_set_setpoint(68.0f);

    printf("1. cold house at 60F, boot lockout then heat\n");
    run(60.0f, 1, 120);

    printf("\n2. house reaches 69F -- must serve min-on before stopping\n");
    run(69.0f, 1, 300);

    printf("\n3. cold again immediately -- must serve min-off\n");
    run(60.0f, 1, 400);

    printf("\n4. hammer it: alternate hot/cold to trip the cycles-per-hour cap\n");
    for (int i = 0; i < 12; i++) {
        run(69.0f, 1, 200);
        run(60.0f, 1, 400);
    }
    thermostat_get_status(&st);
    printf("   -> cycles in last hour: %u (cap %d)\n",
           st.cycles_last_hour, THERM_MAX_CYCLES_PER_HOUR);
    if (st.cycles_last_hour > THERM_MAX_CYCLES_PER_HOUR) {
        printf("   *** FAIL: cap exceeded\n");
        return 1;
    }

    printf("\n5. sensor goes away -- rides it out, then forces heat off\n");
    thermostat_init(t_ms);
    last = (therm_state_t)-1;
    thermostat_set_setpoint(68.0f);
    run(60.0f, 1, 120);          /* heating */
    run(0.0f, 0, 14 * 60);       /* stale but within the grace window */
    run(0.0f, 0, 3 * 60);        /* past it */
    thermostat_get_status(&st);
    if (st.state != THERM_STATE_NO_SENSOR || st.heat_relay) {
        printf("   *** FAIL: expected NO_SENSOR with heat off\n");
        return 1;
    }

    printf("\n6. mode off stops heat immediately, ignoring min-on\n");
    thermostat_init(t_ms);
    last = (therm_state_t)-1;
    thermostat_set_setpoint(68.0f);
    run(60.0f, 1, 120);
    thermostat_get_status(&st);
    if (!st.heat_relay) {
        printf("   *** FAIL: expected to be heating first\n");
        return 1;
    }
    thermostat_set_mode(THERM_MODE_OFF);
    run(60.0f, 1, 2);
    thermostat_get_status(&st);
    if (st.heat_relay) {
        printf("   *** FAIL: heat still on after mode off\n");
        return 1;
    }

    printf("\n7. fan is independent of heat, and never follows a heat call\n");
    thermostat_init(t_ms);
    last = (therm_state_t)-1;
    thermostat_set_setpoint(68.0f);
    run(60.0f, 1, 120);
    thermostat_get_status(&st);
    if (st.fan_relay) {
        printf("   *** FAIL: fan energized during heat (furnace owns the blower)\n");
        return 1;
    }
    thermostat_set_fan(THERM_FAN_ON);
    run(60.0f, 1, 2);
    thermostat_get_status(&st);
    if (!st.fan_relay) {
        printf("   *** FAIL: fan did not turn on\n");
        return 1;
    }

    printf("\nall checks passed\n");
    return 0;
}