56 lines
1.5 KiB
Dart
56 lines
1.5 KiB
Dart
import 'dart:io';
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/// Abstraction for Raspberry Pi hardware I/O
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///
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/// Uses fire-and-forget async reads with synchronous cache returns.
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/// UI always gets immediate response, cache updates in background.
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class PiIO {
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PiIO._() {
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// Kick off initial read
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_refreshTemperature();
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}
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static final instance = PiIO._();
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// Thermal zone file path (returns millidegrees)
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static const _thermalPath = '/sys/class/thermal/thermal_zone0/temp';
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// Cache
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double? _tempCache;
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bool _tempReadInProgress = false;
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/// Get CPU temperature in Celsius (synchronous, returns cached value)
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///
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/// Returns immediately with cached value (or null if no read has completed).
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/// Triggers background refresh if not already in progress.
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double? getTemperature() {
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// Fire off background read if not already running
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if (!_tempReadInProgress) {
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_refreshTemperature();
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}
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return _tempCache;
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}
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/// Background read - updates cache when complete
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Future<void> _refreshTemperature() async {
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if (_tempReadInProgress) return;
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_tempReadInProgress = true;
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try {
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final file = File(_thermalPath);
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if (await file.exists()) {
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final content = await file.readAsString();
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_tempCache = int.parse(content.trim()) / 1000.0;
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}
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} catch (e) {
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// Not on Pi, or permission issue - cache stays as-is
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} finally {
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_tempReadInProgress = false;
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}
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}
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/// Force clear cache (next getTemperature will return null until read completes)
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void clearCache() {
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_tempCache = null;
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}
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}
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