balcony_weather_station/mqtt_client.c

/**
 * MQTT Client to publish sensor data to homeassistant
 * MQTT client doc: https://www.nongnu.org/lwip/2_1_x/group__mqtt.html#gafdfa0e65b217e92835d35858924565cf
 * PICO W MQTT example: https://github.com/raspberrypi/pico-examples/blob/master/pico_w/wifi/mqtt/README
 */

#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"
#include "hardware/adc.h"
#include "lwip/apps/mqtt.h"

// Temperature
#ifndef TEMPERATURE_UNITS
#define TEMPERATURE_UNITS 'C' // Set to 'F' for Fahrenheit
#endif

#ifndef MQTT_SERVER
#error Need to define MQTT_SERVER
#endif

// This file includes your client certificate for client server authentication
#ifdef MQTT_CERT_INC
#include MQTT_CERT_INC
#endif

#ifndef MQTT_TOPIC_LEN
#define MQTT_TOPIC_LEN 100
#endif

typedef struct {
    mqtt_client_t* mqtt_client_inst;
    struct mqtt_connect_client_info_t mqtt_client_info;
    char data[MQTT_OUTPUT_RINGBUF_SIZE];
    char topic[MQTT_TOPIC_LEN];
    uint32_t len;
    ip_addr_t mqtt_server_address;
    bool connect_done;
    int subscribe_count;
    bool stop_client;
} MQTT_CLIENT_DATA_T;

#ifndef DEBUG_printf
#ifndef NDEBUG
#define DEBUG_printf printf
#else
#define DEBUG_printf(...)
#endif
#endif

#ifndef INFO_printf
#define INFO_printf printf
#endif

#ifndef ERROR_printf
#define ERROR_printf printf
#endif

// how often to measure our temperature
#define TEMP_WORKER_TIME_S 10

// keep alive in seconds
#define MQTT_KEEP_ALIVE_S 60

// qos passed to mqtt_subscribe
// At most once (QoS 0)
// At least once (QoS 1)
// Exactly once (QoS 2)
#define MQTT_PUBLISH_QOS 1
#define MQTT_PUBLISH_RETAIN 0
#define MQTT_DEVICE_NAME "pico_test_001"

// Set to 1 to add the client name to topics, to support multiple devices using the same server
//
#define MQTT_TOPIC "bws/test1/state"

/* References for this implementation:
 * raspberry-pi-pico-c-sdk.pdf, Section '4.1.1. hardware_adc'
 * pico-examples/adc/adc_console/adc_console.c */
static float read_onboard_temperature(const char unit) {

    /* 12-bit conversion, assume max value == ADC_VREF == 3.3 V */
    const float conversionFactor = 3.3f / (1 << 12);

    float adc = (float)adc_read() * conversionFactor;
    float tempC = 27.0f - (adc - 0.706f) / 0.001721f;

    if (unit == 'C' || unit != 'F') {
        return tempC;
    } else if (unit == 'F') {
        return tempC * 9 / 5 + 32;
    }

    return -1.0f;
}

static void pub_request_cb(__unused void *arg, err_t err) {
    if (err != 0) {
        ERROR_printf("pub_request_cb failed %d", err);
    }
}

static void publish_temperature(MQTT_CLIENT_DATA_T *state) {
    static float old_temperature;
    float temperature = read_onboard_temperature(TEMPERATURE_UNITS);
    if (temperature != old_temperature) {
        old_temperature = temperature;
        // Publish temperature on /temperature topic
        char temp_str[16];
        snprintf(temp_str, sizeof(temp_str), "%.2f", temperature);
        INFO_printf("Publishing Temp %s\n", temp_str);
        mqtt_publish(state->mqtt_client_inst, MQTT_TOPIC, temp_str, strlen(temp_str), MQTT_PUBLISH_QOS, MQTT_PUBLISH_RETAIN, pub_request_cb, state);
    }
}

static void sub_request_cb(void *arg, err_t err) {
    MQTT_CLIENT_DATA_T* state = (MQTT_CLIENT_DATA_T*)arg;
    if (err != 0) {
        panic("subscribe request failed %d", err);
    }
    state->subscribe_count++;
}

static void unsub_request_cb(void *arg, err_t err) {
    MQTT_CLIENT_DATA_T* state = (MQTT_CLIENT_DATA_T*)arg;
    if (err != 0) {
        panic("unsubscribe request failed %d", err);
    }
    state->subscribe_count--;
    assert(state->subscribe_count >= 0);

    // Stop if requested
    if (state->subscribe_count <= 0 && state->stop_client) {
        mqtt_disconnect(state->mqtt_client_inst);
    }
}

static void temperature_worker_fn(async_context_t *context, async_at_time_worker_t *worker) {
    MQTT_CLIENT_DATA_T* state = (MQTT_CLIENT_DATA_T*)worker->user_data;
    publish_temperature(state);
    async_context_add_at_time_worker_in_ms(context, worker, TEMP_WORKER_TIME_S * 1000);
}
static async_at_time_worker_t temperature_worker = { .do_work = temperature_worker_fn };

static void mqtt_connection_cb(mqtt_client_t *client, void *arg, mqtt_connection_status_t status) {
    MQTT_CLIENT_DATA_T* state = (MQTT_CLIENT_DATA_T*)arg;
    if (status == MQTT_CONNECT_ACCEPTED) {
        state->connect_done = true;

        // Publish temperature every 10 sec if it's changed
        temperature_worker.user_data = state;
        async_context_add_at_time_worker_in_ms(cyw43_arch_async_context(), &temperature_worker, 0);
    } else if (status == MQTT_CONNECT_DISCONNECTED) {
        if (!state->connect_done) {
            panic("Failed to connect to mqtt server");
        }
    }
    else {
        panic("Unexpected status");
    }
}

static void start_client(MQTT_CLIENT_DATA_T *state) {
    const int port = MQTT_PORT;
    state->mqtt_client_inst = mqtt_client_new();
    if (!state->mqtt_client_inst) {
        panic("MQTT client instance creation error");
    }
    INFO_printf("IP address of this device %s\n", ipaddr_ntoa(&(netif_list->ip_addr)));
    INFO_printf("Connecting to mqtt server at %s\n", ipaddr_ntoa(&state->mqtt_server_address));

    cyw43_arch_lwip_begin();
    if (mqtt_client_connect(state->mqtt_client_inst, &state->mqtt_server_address, port, mqtt_connection_cb, state, &state->mqtt_client_info) != ERR_OK) {
        panic("MQTT broker connection error");
    }
    cyw43_arch_lwip_end();
}

int main(void) {
    stdio_init_all();
    INFO_printf("mqtt client starting\n");

    adc_init();
    adc_set_temp_sensor_enabled(true);
    adc_select_input(4);

    static MQTT_CLIENT_DATA_T state;

    if (cyw43_arch_init()) {
        panic("Failed to inizialize CYW43");
    }

    state.mqtt_client_info.client_id = MQTT_DEVICE_NAME;
    state.mqtt_client_info.keep_alive = MQTT_KEEP_ALIVE_S; // Keep alive in sec
    state.mqtt_client_info.client_user = MQTT_USERNAME;
    state.mqtt_client_info.client_pass = MQTT_PASSWORD;
    ip_addr_t ip_addr;
     // Initialize the IP address
     if (ipaddr_aton(MQTT_SERVER, &ip_addr)) {
         printf("IP address is valid and initialized.\n");
     } else {
         printf("Invalid IP address format.\n");
     }
    state.mqtt_server_address = ip_addr;

    cyw43_arch_enable_sta_mode();
    if (cyw43_arch_wifi_connect_timeout_ms(WIFI_SSID, WIFI_PASSWORD, CYW43_AUTH_WPA2_AES_PSK, 30000)) {
        panic("Failed to connect");
    }
    INFO_printf("\nConnected to Wifi\n");

    start_client(&state);

    while (!state.connect_done || mqtt_client_is_connected(state.mqtt_client_inst)) {
        cyw43_arch_poll();
        cyw43_arch_wait_for_work_until(make_timeout_time_ms(10000));
    }

    INFO_printf("mqtt client exiting\n");
    return 0;
}