Simplified data storage without eeprom, include timestamps

include/bluetooth.h

@@ -4,9 +4,6 @@
 
 void bluetoothConfigure();
 
+void bluetoothStop();
+
 bool bluetoothIsConnected();
-
-// In main.cpp
-uint32_t secondsUntilNextTemperatureMeasurement();
-
-uint8_t getWakeupCause();

include/eepromInterface.h

@@ -0,0 +1,90 @@
+#include <stdint.h>
+#include <stddef.h>
+
+#pragma pack(push, 1)
+struct DeviceInfo {
+    
+    // The index where the measurement data starts in the eeprom storage
+    uint16_t startIndex;
+
+    // The time when the device was powered on (seconds since 1970)
+    uint32_t deviceStartTime;
+};
+
+struct Measurement {
+
+    uint16_t measurementIntervalsSinceDeviceStart;
+
+    uint8_t temperature0;
+
+    uint8_t temperature1;
+};
+#pragma pack(pop)
+
+constexpr size_t eepromTotalSize = 13350;
+constexpr uint16_t maxiumDeviceInfoCount = 10;
+constexpr uint16_t dataStorageStartIndex = sizeof(DeviceInfo) * maxiumDeviceInfoCount;
+constexpr uint16_t sizeOfMeasurement = sizeof(Measurement);
+
+class EEPROMInterface {
+
+public:
+
+    bool isInitialized;
+
+    /**
+     * @brief Initialize the storage
+     * 
+     */
+    EEPROMInterface();
+
+    /**
+     * @brief 
+     * 
+     */
+   uint8_t startNewDeviceSession();
+
+    /**
+     * @brief Remove all stored data
+     * 
+     * @return true The data was deleted
+     * @return false There was an error deleting the data
+     */
+    bool clearAllData();
+
+    bool writeData(uint8_t* data, uint16_t count);
+
+    /**
+     * @brief Free space in the buffer 
+     * 
+     * @param buffer 
+     * @param count 
+     * @return uint16_t The number 
+     */
+    uint16_t readData(uint8_t* buffer, uint16_t count);
+
+    uint16_t getStoredByteCount();
+
+private:
+
+    /**
+     * @brief The index into the buffer where the next byte should be written
+     * 
+     */
+    uint16_t writeIndex;
+
+    /**
+     * @brief The index into the buffer where the first byte is stored
+     * 
+     */
+    uint16_t readIndex;
+
+    /**
+     * @brief Find the write index, the first zero byte after a non-zero byte
+     * 
+     * @return uint16_t The write index
+     */
+    uint16_t findEndIndex();
+
+    uint16_t findStartIndex();
+};

include/main.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <stdint.h>
+
+uint32_t secondsUntilNextTemperatureMeasurement();
+uint8_t getWakeupCause();
+uint32_t getUniqueID();

include/storage.h

@@ -6,33 +6,17 @@
 
 constexpr uint8_t temperatureSensorCount = 2;
 
-constexpr size_t storageSize = 80000;
-constexpr uint16_t storageIntervalInSeconds = 15;
-constexpr size_t maximumStorageDurationInHours = (storageSize / TEMPERATURE_SENSOR_MAX_COUNT) * storageIntervalInSeconds / 3600;
-
 // Max size: 7664
-constexpr size_t maxRtcStorageSize = 7664;
+constexpr size_t rtcStorageSize = 7580;
-constexpr size_t rtcStorageSize = 7550;
 
 constexpr size_t maxEepromSize = 13350;
-constexpr size_t eepromSize = 13350;
-
-constexpr size_t totalStorageSize = rtcStorageSize + eepromSize;
 
 // The minimum temperature to store, in millidegrees celcius
 // True minimum will be higher by 1°, since two values are reserved 
 constexpr long temperatureShiftForStorage = -40000;
 constexpr long maximumTemperature = temperatureShiftForStorage + 255 * 500;
-
 constexpr uint8_t temperatureMaximumValue = 255;
 
-enum class StorageFlags: uint8_t {
-    HasInitializedEEPROM = 1,
-    FailedToInitEEPROM = 2,
-    FailedToWriteEEPROM = 4,
-    RTCStorageOverflow = 5,
-};
-
 void storageConfigure(bool isFirstRun);
 
 /**
@@ -51,12 +35,14 @@ uint16_t getNumberOfMeasurements();
 
 uint32_t getTotalNumberOfMeasurements();
 
+uint32_t getStartTimeOfCurrentRecording();
+
 uint8_t getLastTemperature(uint8_t sensorIndex);
 
 uint16_t getTimeSinceValidTemperature(uint8_t sensorIndex);
 
 uint16_t getRecordedBytesAtOffset(uint8_t* buffer, uint16_t offset, uint16_t count);
 
-void discardAllRecordedBytes();
+uint16_t getDataChecksum();
 
-uint8_t getStorageErrorFlags();
+void discardAllRecordedBytes();

src/bluetooth.cpp

@@ -1,5 +1,6 @@
 #include <string.h>
 #include <Esp.h>
+#include <stdint.h>
 
 #include <BLEDevice.h>
 #include <BLEUtils.h>
@@ -10,6 +11,7 @@
 #include "storage.h"
 #include "config.h"
 #include "temperature.h"
+#include "main.h"
 
 constexpr size_t bluetoothMaxDataSize = 200;
 
@@ -29,8 +31,6 @@ uint8_t* bluetoothDataBuffer;
 uint8_t* bluetoothResponse;
 size_t bluetoothDataCount = 0;
 
-RTC_DATA_ATTR uint32_t deviceStartTime = 0;
-
 void bluetoothStartAdvertising();
 void bluetoothDidReceiveData(uint8_t* buffer, uint16_t count);
 
@@ -87,7 +87,6 @@ void bluetoothConfigure() {
     BLEDevice::init(deviceName);
     server = BLEDevice::createServer();
     server->setCallbacks(&bluetooth);
-    
     // Register message service that can receive messages and reply with a static message.
     BLEService *service = server->createService(serviceUUID);
     uint32_t properties = BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY | BLECharacteristic::PROPERTY_WRITE;
@@ -114,6 +113,11 @@ void bluetoothConfigure() {
     bluetoothStartAdvertising();
 }
 
+void bluetoothStop() {
+    BLEDevice::deinit();
+    esp_bt_controller_disable();
+}
+
 void bluetoothStartAdvertising() {
     // Advertise services
     BLEAdvertising *advertisement = server->getAdvertising();
@@ -171,17 +175,6 @@ enum class BluetoothRequest: uint8_t {
      *   This may happen when a new temperature recording is performed in between calls
      */
     clearRecordingBuffer = 2,
-
-    /**
-     * @brief Set the absolute start time of the device
-     * 
-     * Request:
-     * - Bytes 1-4: Number of seconds since 1970 (uint32_t)
-     * 
-     * Response: 
-     * - BluetoothResponse::success
-     */
-    setDeviceStartTime = 3,
 };
 
 enum class BluetoothResponse: uint8_t {
@@ -237,6 +230,11 @@ void fillInfo() {
     uint16_t value;
     uint32_t value32;
 
+    // The unique ID generated on power-on
+    value32 = getUniqueID();
+    memcpy(bluetoothDataBuffer + bluetoothDataCount, &value32, sizeof(uint32_t));
+    bluetoothDataCount += sizeof(uint32_t);
+
     // the number of bytes as a uint16_t (2 bytes)
     value = getTotalNumberOfStoredBytes();
     memcpy(bluetoothDataBuffer, &value, sizeof(uint16_t));
@@ -268,7 +266,7 @@ void fillInfo() {
     bluetoothDataCount += sizeof(uint16_t);
 
     // Total storage size of device
-    value = totalStorageSize;
+    value = rtcStorageSize;
     memcpy(bluetoothDataBuffer + bluetoothDataCount, &value, sizeof(uint16_t));
     bluetoothDataCount += sizeof(uint16_t);
 
@@ -277,10 +275,20 @@ void fillInfo() {
     memcpy(bluetoothDataBuffer + bluetoothDataCount, &value32, sizeof(uint32_t));
     bluetoothDataCount += sizeof(uint32_t);
 
-    // Configured device start time
+    // Start time of current recording
-    memcpy(bluetoothDataBuffer + bluetoothDataCount, &deviceStartTime, sizeof(uint32_t));
+    value32 = getStartTimeOfCurrentRecording();
+    memcpy(bluetoothDataBuffer + bluetoothDataCount, &value32, sizeof(uint32_t));
     bluetoothDataCount += sizeof(uint32_t);
 
+    // Checksum for all data
+    value = getDataChecksum();
+    memcpy(bluetoothDataBuffer + bluetoothDataCount, &value, sizeof(uint16_t));
+    bluetoothDataCount += sizeof(uint16_t);
+
+    // The wakeup cause for the current run
+    bluetoothDataBuffer[bluetoothDataCount] = getWakeupCause();
+    bluetoothDataCount += sizeof(uint8_t);
+
     // Sensor 0
 
     // Temperature sensor addresses
@@ -309,9 +317,6 @@ void fillInfo() {
     memcpy(bluetoothDataBuffer + bluetoothDataCount, &value, sizeof(uint16_t));
     bluetoothDataCount += sizeof(uint16_t);
 
-    bluetoothDataBuffer[bluetoothDataCount] = getWakeupCause();
-    bluetoothDataCount += sizeof(uint8_t);
-
     setResponse(BluetoothResponse::success);
 }
 
@@ -350,17 +355,6 @@ void clearRecordingBuffer(uint8_t* buffer, uint16_t count) {
     setResponseWithoutData(BluetoothResponse::success);
 }
 
-void setDeviceStartTime(uint8_t* buffer, uint16_t count) {
-    if (count != sizeof(uint32_t)) {
-        setResponseWithoutData(BluetoothResponse::invalidCommand);
-        return;
-    }
-    memcpy(&deviceStartTime, buffer, sizeof(uint32_t));
-    Serial.print("Device start time: ");
-    Serial.println(deviceStartTime);
-    setResponseWithoutData(BluetoothResponse::success);
-}
-
 void bluetoothDidReceiveData(uint8_t* buffer, uint16_t count) {
     if (count < 1) {
         setResponseWithoutData(BluetoothResponse::invalidCommand);
@@ -384,10 +378,6 @@ void bluetoothDidReceiveData(uint8_t* buffer, uint16_t count) {
         getRecordingData(payload, payloadSize);
         break;
 
-    case BluetoothRequest::setDeviceStartTime:
-        setDeviceStartTime(payload, payloadSize);
-        break;
-    
     default:
         setResponseWithoutData(BluetoothResponse::unknownCommand);
         break;

src/eepromInterface.cpp

@@ -0,0 +1,6 @@
+#include "eepromInterface.h"
+#include <EEPROM.h>
+
+EEPROMInterface::EEPROMInterface() {
+    isInitialized = EEPROM.begin(eepromTotalSize);
+}

src/main.cpp

@@ -2,6 +2,7 @@
 #include <esp_wifi.h>
 #include <driver/rtc_io.h>
 
+#include "main.h"
 #include "config.h"
 #include "bluetooth.h"
 #include "storage.h"
@@ -16,6 +17,9 @@ RTC_DATA_ATTR uint32_t nextTimeToMeasureTemperatureSeconds = 0;
 
 RTC_DATA_ATTR bool isFirstStart = true;
 
+// The unique ID generated whenever the device is powered on
+RTC_DATA_ATTR uint32_t uniqueID;
+
 // Indicate the time until the device should stay awake
 // Updated when button is pressed
 uint32_t sleepStartAfterButtonPressOrConnection = 0;
@@ -26,6 +30,10 @@ uint8_t getWakeupCause() {
     return wakeupCauseByte;
 }
 
+uint32_t getUniqueID() {
+    return uniqueID;
+}
+
 /**
  * @brief Check if enough time has passed for the next temperature measurement
  * 
@@ -54,7 +62,8 @@ uint32_t secondsUntilNextTemperatureMeasurement() {
     if (currentTime >= nextTimeToMeasureTemperatureSeconds) {
         return 0;
     }
-    return nextTimeToMeasureTemperatureSeconds - currentTime;
+    uint32_t seconds = nextTimeToMeasureTemperatureSeconds - currentTime;
+    return min(seconds, temperatureMeasurementIntervalSeconds);
 }
 
 /**
@@ -74,6 +83,7 @@ void deepSleepUntilNextTemperatureMeasurement() {
     Serial.print("Sleeping for ");
     Serial.print(seconds);
     Serial.println(" seconds");
+    bluetoothStop();
     esp_deep_sleep(seconds * 1000000);
 }
 
@@ -127,6 +137,11 @@ void setup() {
     // No need for serial output in production
     Serial.begin(serialBaudRate);
 
+    if (isFirstStart) {
+        // Generate unique ID on device start
+        uniqueID = random();
+    }
+    
     // LED useless inside case
     // enableLED();
     

src/storage.cpp

@@ -3,63 +3,21 @@
 #include <EEPROM.h>
 #include <esp_attr.h>
 
-constexpr uint8_t absoluteTemperatureIndicator = 0xFF;
-
-RTC_DATA_ATTR uint8_t storageFlags = 0;
-
 // Storage for temperature measurements in RTC memory that survives deep sleep
 RTC_DATA_ATTR uint8_t data[rtcStorageSize];
-RTC_DATA_ATTR uint16_t dataIndex = 0;
+RTC_DATA_ATTR uint16_t dataIndex = 0; // Index of next byte / total byte count
-RTC_DATA_ATTR uint16_t numberOfMeasurements = 0;
+RTC_DATA_ATTR uint16_t rtcDataSum = 0; // Checksum for the data storage
-RTC_DATA_ATTR uint32_t numberOfDiscardedMeasurements = 0;
+RTC_DATA_ATTR uint16_t numberOfMeasurements = 0; // Current number of measurements (dataIndex / 4)
+RTC_DATA_ATTR uint32_t numberOfDiscardedMeasurements = 0; // Previous measurements already deleted
 
-// The index into EEPROM storage where the next data should be written
+// The time (in seconds since device start) when the current recording started
-RTC_DATA_ATTR uint32_t eepromIndex = 0;
+RTC_DATA_ATTR uint32_t startTimeOfCurrentRecording = 0;
-RTC_DATA_ATTR bool isFirstRunAfterPowerOn = true;
-
-constexpr uint16_t eepromOffset = sizeof(uint16_t);
-constexpr uint16_t eepromDataSize = eepromSize - eepromOffset;
 
 // Keeps the last valid temperatures for each sensor
 RTC_DATA_ATTR Temperature lastTemperatures[temperatureSensorCount];
 RTC_DATA_ATTR uint32_t lastValidTemperatureTime[temperatureSensorCount];
 RTC_DATA_ATTR uint8_t lastMeasurements[temperatureSensorCount] = {0, 0};
 
-void setStorageFlag(StorageFlags flag) {
-    storageFlags |= static_cast<uint8_t>(flag);
-}
-
-void clearStorageFlag(StorageFlags flag) {
-    storageFlags &= ~static_cast<uint8_t>(flag);
-}
-
-bool hasStorageFlag(StorageFlags flag) {
-    return storageFlags & static_cast<uint8_t>(flag);
-}
-
-bool hasInitializedEEPROM() {
-    return hasStorageFlag(StorageFlags::HasInitializedEEPROM);
-}
-
-void didInitializeEEPROM() {
-    setStorageFlag(StorageFlags::HasInitializedEEPROM);
-}
-
-void setupEEPROMIfNeeded() {
-    if (hasInitializedEEPROM()) {
-        return;
-    }
-    bool success = EEPROM.begin(eepromSize);
-    if (!success) {
-        Serial.println("Failed to set up EEPROM");
-        setStorageFlag(StorageFlags::FailedToInitEEPROM);
-    }
-    Serial.print("EEPROM size: ");
-    Serial.println(eepromSize);
-    clearStorageFlag(StorageFlags::FailedToInitEEPROM);
-    setStorageFlag(StorageFlags::HasInitializedEEPROM);
-}
-
 void resetLastMeasurements() {
     for (uint8_t index = 0; index < temperatureSensorCount; index += 1) {
         lastTemperatures[index].status == TemperatureStatus::sensorNotFound;
@@ -74,41 +32,6 @@ void storageConfigure(bool isFirstRun) {
         // Ensure that first values are stored
         resetLastMeasurements();
     }
-    // Initialize EEPROM on every wake
-    // setupEEPROMIfNeeded();
-    //setStorageFlag(StorageFlags::HasInitializedEEPROM);
-}
-
-void moveDataToEEPROMIfNeeded() {
-    if (dataIndex < rtcStorageSize) {
-        return;
-    }
-
-    setupEEPROMIfNeeded();
-    if (!hasInitializedEEPROM()) {
-        return;
-    }
-
-    // Write until EEPROM is full
-    uint16_t bytesRemaining = eepromDataSize - eepromIndex;
-    uint16_t bytesToWrite = min(dataIndex, bytesRemaining);
-    EEPROM.writeBytes(eepromIndex, data, bytesToWrite); // TODO: Check that result == bytesToWrite
-    EEPROM.commit();
-
-    // Move remaining data to front of array (if any)
-    uint16_t bytesToKeep = dataIndex - bytesToWrite;
-    memmove(data, data + bytesToWrite, bytesToKeep);
-    dataIndex -= bytesToWrite;
-}
-
-void saveByteAtCurrentIndex(uint8_t byte) {
-    if (dataIndex >= rtcStorageSize) {
-        setStorageFlag(StorageFlags::RTCStorageOverflow);
-        return;
-    }
-    data[dataIndex] = byte;
-    dataIndex += 1;
-    //moveDataToEEPROMIfNeeded();
 }
 
 uint8_t byteForAbsoluteTemperature(Temperature* temp) {
@@ -139,32 +62,28 @@ uint8_t byteForAbsoluteTemperature(Temperature* temp) {
     return converted;
 }
 
-bool needsAbsoluteTemperatureRecording(Temperature* temperatures) {
-    if (numberOfMeasurements == 0) {
-        return true;
-    }
-    for (uint8_t index = 0; index < temperatureSensorCount; index += 1) {
-        if (temperatures[index].status != TemperatureStatus::temperatureIsValid) {
-            // Error value can be encoded as differential (0x00)
-            continue;
-        }
-        // Note: If previously only errors, then last value is 0. This also work for differential temperatures
-        long diff = (lastTemperatures[index].value - temperatures[index].value) / 500 + 8;
-        if (diff < 1 || diff > 15) {
-            return true;
-        }
-    }
-    return false;
-}
-
 void saveTemperatures(Temperature* temperatures) {
-    if (needsAbsoluteTemperatureRecording(temperatures)) {
+    if (numberOfMeasurements == 0) {
-        // Write absolute temperatures
+        // Adjust start time if new measurement is begun
-        saveByteAtCurrentIndex(absoluteTemperatureIndicator);
+        startTimeOfCurrentRecording = time(NULL);
+    }
+    if (dataIndex + 4 >= rtcStorageSize) {
+        // Don't add any more measurements if storage is full
+        return;
+    }
+    // First: Write timestamp
+    // Timestamp is number of measurement intervals since start of recording
+    uint16_t timestamp = (time(NULL) - startTimeOfCurrentRecording) / 60;
+    memcpy(data + dataIndex, &timestamp, sizeof(uint16_t));
+    rtcDataSum += data[dataIndex] + data[dataIndex+1]; // Update checksum
+    dataIndex += sizeof(uint16_t);
+
     for (uint8_t sensorIndex = 0; sensorIndex < temperatureSensorCount; sensorIndex += 1) {
         Temperature* temp = &temperatures[sensorIndex];
         uint8_t byte = byteForAbsoluteTemperature(temp);
-            saveByteAtCurrentIndex(byte);
+        data[dataIndex] = byte;
+        dataIndex += 1;
+        rtcDataSum += byte; // Update checksum
         lastMeasurements[sensorIndex] = byte;
         if (temp->status == TemperatureStatus::temperatureIsValid) {
             // Only update if temperature is valid
@@ -172,46 +91,11 @@ void saveTemperatures(Temperature* temperatures) {
             lastValidTemperatureTime[sensorIndex] = time(NULL);
         }
     }
-    } else {
-        // Calculate temperature differences
-        uint8_t valueToStore = 0;
-        for (uint8_t index = 0; index < temperatureSensorCount; index += 1) {
-            Temperature* temp = &temperatures[index];
-            uint8_t diff = 0; // Indicate sensor error
-            if (temp->status == TemperatureStatus::temperatureIsValid) {
-                diff = (lastTemperatures[index].value - temp->value) / 500 + 8;
-            }
-            if (index % 2) {
-                // Store second bits
-                valueToStore |= diff; // Valid range already ensured
-                saveByteAtCurrentIndex(valueToStore);
-                valueToStore = 0;
-            } else {
-                // Store in first four bits
-                valueToStore = (diff << 4);
-            }
-            lastMeasurements[index] = byteForAbsoluteTemperature(temp);
-
-            if (temp->status == TemperatureStatus::temperatureIsValid) {
-                // Only update if temperature is valid
-                lastTemperatures[index].status = TemperatureStatus::temperatureIsValid;
-                lastTemperatures[index].value = temp->value;
-                lastValidTemperatureTime[index] = time(NULL);
-            } else if (lastTemperatures[index].status != TemperatureStatus::temperatureIsValid) {
-                lastTemperatures[index].value = 0;
-                lastValidTemperatureTime[index] = 0;
-            }
-        }
-        // Ensure storage with uneven number of sensors
-        if (temperatureSensorCount % 2) {
-            saveByteAtCurrentIndex(valueToStore);
-        }
-    }
     numberOfMeasurements += 1;
 }
 
 uint16_t getTotalNumberOfStoredBytes() {
-    return dataIndex; // + eepromIndex;
+    return dataIndex;
 }
 
 uint16_t getNumberOfMeasurements() {
@@ -222,48 +106,35 @@ uint32_t getTotalNumberOfMeasurements() {
     return numberOfMeasurements + numberOfDiscardedMeasurements;
 }
 
+uint32_t getStartTimeOfCurrentRecording() {
+    return startTimeOfCurrentRecording;
+}
+
 uint8_t getLastTemperature(uint8_t sensorIndex) {
     return lastMeasurements[sensorIndex];
 }
 
 uint16_t getTimeSinceValidTemperature(uint8_t sensorIndex) {
-    return time(NULL) - lastValidTemperatureTime[sensorIndex];
+    return min(time(NULL) - lastValidTemperatureTime[sensorIndex], 65535ul);
 }
 
 uint16_t getRecordedBytesAtOffset(uint8_t* buffer, uint16_t offset, uint16_t count) {
-    // Copy remaining bytes from RTC memory
+    if (offset >= dataIndex) {
+        return 0;
+    }
     uint16_t remainingBytes = dataIndex - offset;
     uint16_t bytesToCopy = min(count, remainingBytes);
-    memcpy(buffer, data + offset, count);
+    memcpy(buffer, data + offset, bytesToCopy);
     return bytesToCopy;
-    /*
+}
-    // TODO: Check limits
+
-    uint16_t eepromByteCount = eepromIndex;
+uint16_t getDataChecksum() {
-    uint16_t endIndex = offset + count;
+    return rtcDataSum;
-    uint16_t eepromStart = min(offset, eepromByteCount);
-    uint16_t eepromEnd = min(endIndex, eepromByteCount);
-    uint16_t bytesToCopyFromEEPROM = eepromEnd - eepromStart;
-    if (bytesToCopyFromEEPROM > 0) {
-        EEPROM.readBytes(eepromStart, buffer, bytesToCopyFromEEPROM); // TODO: Check bytes read
-        // Reduce offset and count to point to RTC memory
-        offset -= bytesToCopyFromEEPROM;
-        count -= bytesToCopyFromEEPROM;
-    }
-    offset -= eepromByteCount;
-    // Copy remaining bytes from RTC memory
-    uint16_t bytesToCopyFromRTC = min(count, dataIndex);
-    memcpy(buffer + bytesToCopyFromEEPROM, data + offset, bytesToCopyFromRTC);
-    return bytesToCopyFromEEPROM + bytesToCopyFromRTC;
-    */
 }
 
 void discardAllRecordedBytes() {
-    eepromIndex = 0;
     dataIndex = 0;
+    rtcDataSum = 0;
     numberOfDiscardedMeasurements += numberOfMeasurements;
     numberOfMeasurements = 0;
 }
-
-uint8_t getStorageErrorFlags() {
-    return storageFlags;
-}