Start work on power saving modes.

TNC/PowerMode.cpp

@@ -0,0 +1,52 @@
+// Copyright 2018 Rob Riggs <rob@mobilinkd.com>
+// All rights reserved.
+
+#include "main.h"
+#include "PowerMode.h"
+#include "stm32l4xx_hal.h"
+
+#include <stdint.h>
+
+volatile PowerMode power_mode{PowerMode::RUN};
+PowerMode previous_mode{PowerMode::RUN};        // Always start in RUN mode.
+
+/**
+ * Handle state transitions here.  Valid transitions are from RUN to any mode,
+ * LPRUN to any mode, SLEEP to LPRUN or STOP, and STOP to LPRUN or SLEEP.
+ *
+ * If moving from RUN to any SLEEP or STOP, we assume the upper layers have
+ * already disconnected the connection, either bu
+ *
+ * @param ulExpectedIdleTime
+ */
+extern "C" void PreSleepProcessing(uint32_t *ulExpectedIdleTime)
+{
+    switch (power_mode)
+    {
+    case PowerMode::RUN:
+        break;
+    case PowerMode::LPRUN:
+        if (previous_mode != power_mode);
+        break;
+    case PowerMode::SLEEP:
+        break;
+    case PowerMode::STOP:
+        break;
+    }
+}
+
+extern "C" void PostSleepProcessing(uint32_t *ulExpectedIdleTime)
+{
+    switch (power_mode)
+    {
+    case PowerMode::RUN:
+        break;
+    case PowerMode::LPRUN:
+        break;
+    case PowerMode::SLEEP:
+        break;
+    case PowerMode::STOP:
+        break;
+    }
+}
+

TNC/PowerMode.h

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+// Copyright 2018 Rob Riggs <rob@mobilinkd.com>
+// All rights reserved.
+
+#ifndef TNC_POWERMODE_H_
+#define TNC_POWERMODE_H_
+
+enum class PowerMode {
+    RUN,        // Power on, connected.
+    LPRUN,      // Power on, not connected.
+    SLEEP,      // Power off, USB connected.
+    STOP        // Power off, no USB connection.
+};
+
+extern volatile PowerMode power_mode;
+
+#endif // TNC_POWERMODE_H_