refactor setup tasks

src/main.rs

@@ -5,26 +5,32 @@ use chrono::{NaiveTime, Utc};
 use chrono_tz::US::Pacific;
 use esp_idf_svc::{
     eventloop::EspSystemEventLoop,
-    hal::{delay::FreeRtos, gpio::*, modem::Modem, peripheral::Peripheral, prelude::Peripherals},
-    sntp::{EspSntp, SntpConf, SyncMode, SyncStatus},
-    wifi::{AuthMethod, BlockingWifi, ClientConfiguration, Configuration, EspWifi},
+    hal::{delay::FreeRtos, gpio::*, prelude::Peripherals},
+    sntp::{EspSntp, SntpConf, SyncMode},
+    wifi::EspWifi,
 };
 use log::info;
 
 mod config;
+mod ntp;
+mod wifi;
 
-const SNTP_STATUS_POLL_INTVL_MS: u32 = 2000;
 /// Delay between executions of the main control loop, in milliseconds.
 const CONTROL_LOOP_INTVL: u32 = 60000;
 
-fn main() -> Result<()> {
-    // It is necessary to call this function once. Otherwise some patches to
-    // the runtime implemented by esp-idf-sys might not link properly. Refer
-    // to https://github.com/esp-rs/esp-idf-template/issues/71.
-    esp_idf_svc::sys::link_patches();
+/// Struct holding resources which should remain in scope throughout execution.
+struct AppState {
+    ntp: EspSntp<'static>,
+    switch_driver: PinDriver<'static>,
+    wifi: EspWifi<'static>,
+}
 
-    // Bind the log crate to the ESP Logging facilities
-    esp_idf_svc::log::EspLogger::initialize_default();
+fn main() -> Result<()> {
+    let AppState {
+        ntp: mut_ntp,
+        mut switch_driver,
+        wifi: _wifi,
+    } = setup()?;
 
     let t_on = NaiveTime::parse_from_str(config::T_ON, "%H:%M")?;
     let t_off = NaiveTime::parse_from_str(config::T_OFF, "%H:%M")?;
@@ -32,32 +38,6 @@ fn main() -> Result<()> {
         bail!("t_on and t_off must have distinct values");
     }
 
-    let peripherals = Peripherals::take()?;
-
-    let mut switch = PinDriver::output(peripherals.pins.gpio7)?;
-    switch.set_low()?;
-
-    let sysloop = EspSystemEventLoop::take()?;
-
-    // Dropping EspWifi shuts down the connection, so this variable must remain
-    // in scope.
-    let _wifi = init_wifi(peripherals.modem, sysloop);
-
-    // SNTP client will continue running in the background until this value is
-    // dropped.
-    let ntp = EspSntp::new(&SntpConf {
-        servers: [config::SNTP_SERVER],
-        sync_mode: SyncMode::Smooth,
-        ..Default::default()
-    })?;
-
-    // get_sync_status() returns "Completed" one time and then reverts to
-    // "Reset" on subsequent calls.
-    while ntp.get_sync_status() != SyncStatus::Completed {
-        info!("Waiting for SNTP to sync...");
-        FreeRtos::delay_ms(SNTP_STATUS_POLL_INTVL_MS);
-    }
-
     // ======== Main Control Loop ======== //
     loop {
         let now = Utc::now().with_timezone(&Pacific);
@@ -78,9 +58,9 @@ fn main() -> Result<()> {
         };
 
         if active {
-            switch.set_high()?;
+            switch_driver.set_high()?;
         } else {
-            switch.set_low()?;
+            switch_driver.set_low()?;
         }
 
         // TODO: enter low power mode ("light sleep" or "deep sleep") instead
@@ -89,54 +69,40 @@ fn main() -> Result<()> {
     }
 }
 
-/// Start WiFi module and connect to access point. Returns an error if either
-/// of WiFi startup or connection fail.
-fn init_wifi(
-    modem: impl Peripheral<P = Modem> + 'static,
-    sysloop: EspSystemEventLoop,
-) -> Result<Box<EspWifi<'static>>> {
-    let auth_method = AuthMethod::WPA2Personal;
-    let mut esp_wifi = EspWifi::new(modem, sysloop.clone(), None)?;
-    let mut wifi = BlockingWifi::wrap(&mut esp_wifi, sysloop)?;
-    wifi.set_configuration(&Configuration::Client(ClientConfiguration::default()))?;
+/// Runs initial application startup tasks, including connecting WiFi, syncing
+/// system time over SNTP, and setting the initial switch state. May block for
+/// several seconds, or indefinitely if initial SNTP sync is not successful.
+fn setup() -> Result<Box<AppState>> {
+    // It is necessary to call this function once. Otherwise some patches to
+    // the runtime implemented by esp-idf-sys might not link properly. Refer
+    // to https://github.com/esp-rs/esp-idf-template/issues/71.
+    esp_idf_svc::sys::link_patches();
 
-    info!("Starting wifi...");
-    wifi.start()?;
-    info!("Scanning...");
-    let ap_infos = wifi.scan()?;
-    let ours = ap_infos.into_iter().find(|a| a.ssid == config::WIFI_SSID);
-    let channel = if let Some(ours) = ours {
-        info!(
-            "Found configured access point {} on channel {}",
-            config::WIFI_SSID,
-            ours.channel
-        );
-        Some(ours.channel)
-    } else {
-        info!(
-            "Configured access point {} not found during scanning, will go with unknown channel",
-            config::WIFI_SSID
-        );
-        None
-    };
-    wifi.set_configuration(&Configuration::Client(ClientConfiguration {
-        ssid: config::WIFI_SSID
-            .try_into()
-            .expect("Could not parse the given SSID into WiFi config"),
-        password: config::WIFI_PASS
-            .try_into()
-            .expect("Could not parse the given password into WiFi config"),
-        channel,
-        auth_method,
+    // Bind the log crate to the ESP Logging facilities
+    esp_idf_svc::log::EspLogger::initialize_default();
+
+    let peripherals = Peripherals::take()?;
+    let sysloop = EspSystemEventLoop::take()?;
+
+    let mut switch_driver = PinDriver::output(app_state.peripherals.pins.gpio7)?;
+    switch_driver.set_low()?;
+
+    // Dropping EspWifi shuts down the connection, so this variable must remain
+    // in scope.
+    let wifi = crate::wifi::init(peripherals.modem, sysloop)?;
+
+    // SNTP client will continue running in the background until this value is
+    // dropped.
+    let ntp = EspSntp::new(&SntpConf {
+        servers: [config::SNTP_SERVER],
+        sync_mode: SyncMode::Smooth,
         ..Default::default()
-    }))?;
+    })?;
+    crate::ntp::wait_for_sync(&ntp);
 
-    info!("Connecting wifi...");
-    wifi.connect()?;
-    info!("Waiting for DHCP lease...");
-    wifi.wait_netif_up()?;
-    let ip_info = wifi.wifi().sta_netif().get_ip_info()?;
-    info!("Wifi DHCP info: {:?}", ip_info);
-
-    Ok(Box::new(esp_wifi))
+    Ok(Box::new(AppState {
+        ntp,
+        switch_driver,
+        wifi,
+    }))
 }

src/ntp.rs

@@ -0,0 +1,17 @@
+use esp_idf_svc::sntp::{EspSntp, SyncStatus};
+use log::info;
+
+/// Delay between checks of the initial NTP sync check, in milliseconds.
+const SNTP_STATUS_POLL_INTVL: u32 = 2000;
+
+/// Blocks until the SNTP client reports successful synchronization.
+///
+/// Note that the SNTP client's status flag is reset after it is read. Calling
+/// this function twice will cause the second invocation to wait for the next
+/// synchronization event.
+pub(crate) fn wait_for_sync(client: &EspSntp) {
+    while ntp.get_sync_status() != SyncStatus::Completed {
+        info!("Waiting for SNTP to sync...");
+        FreeRtos::delay_ms(SNTP_STATUS_POLL_INTVL_MS);
+    }
+}

src/wifi.rs

@@ -0,0 +1,62 @@
+use anyhow::Result;
+use esp_idf_svc::{
+    eventloop::EspSystemEventLoop,
+    hal::{modem::Modem, peripheral::Peripheral},
+    wifi::{AuthMethod, BlockingWifi, ClientConfiguration, Configuration, EspWifi},
+};
+use log::{debug, info};
+
+use crate::config;
+
+/// Start WiFi module and connect to access point. Returns an error if either
+/// of WiFi startup or connection fail.
+pub(crate) fn init(
+    modem: impl Peripheral<P = Modem> + 'static,
+    sysloop: EspSystemEventLoop,
+) -> Result<Box<EspWifi<'static>>> {
+    let auth_method = AuthMethod::WPA2Personal;
+    let mut esp_wifi = EspWifi::new(modem, sysloop.clone(), None)?;
+    let mut wifi = BlockingWifi::wrap(&mut esp_wifi, sysloop)?;
+    wifi.set_configuration(&Configuration::Client(ClientConfiguration::default()))?;
+
+    info!("Starting wifi...");
+    wifi.start()?;
+    debug!("Scanning...");
+    let ap_infos = wifi.scan()?;
+    let ours = ap_infos.into_iter().find(|a| a.ssid == config::WIFI_SSID);
+    let channel = if let Some(ours) = ours {
+        debug!(
+            "Found configured access point {} on channel {}",
+            config::WIFI_SSID,
+            ours.channel
+        );
+        Some(ours.channel)
+    } else {
+        debug!(
+            "Configured access point {} not found during scanning, will go with unknown channel",
+            config::WIFI_SSID
+        );
+        None
+    };
+    wifi.set_configuration(&Configuration::Client(ClientConfiguration {
+        ssid: config::WIFI_SSID
+            .try_into()
+            .expect("Could not parse the given SSID into WiFi config"),
+        password: config::WIFI_PASS
+            .try_into()
+            .expect("Could not parse the given password into WiFi config"),
+        channel,
+        auth_method,
+        ..Default::default()
+    }))?;
+
+    debug!("Connecting wifi...");
+    wifi.connect()?;
+    debug!("Waiting for DHCP lease...");
+    wifi.wait_netif_up()?;
+
+    let ip_info = wifi.wifi().sta_netif().get_ip_info()?;
+    info!("Wifi DHCP info: {:?}", ip_info);
+
+    Ok(Box::new(esp_wifi))
+}