From 321e70a188e313820e4cadeae038068d156f1f0d Mon Sep 17 00:00:00 2001
From: rbaron <rbaron@rbaron.net>
Date: Sun, 14 Feb 2021 13:15:41 +0100
Subject: [PATCH] Add battery level to the BLE advertisement packet

---
 .../parasite/ble_advertisement_data.cpp       | 20 ++++++++++++++++--
 .../parasite/ble_advertisement_data.h         | 21 ++++++++++++-------
 code/parasite/src/main.cpp                    | 13 +++++++-----
 3 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/code/parasite/lib/parasite/parasite/ble_advertisement_data.cpp b/code/parasite/lib/parasite/parasite/ble_advertisement_data.cpp
index 8f6fe63..6ad8829 100644
--- a/code/parasite/lib/parasite/parasite/ble_advertisement_data.cpp
+++ b/code/parasite/lib/parasite/parasite/ble_advertisement_data.cpp
@@ -1,11 +1,27 @@
 #include "ble_advertisement_data.h"
 
+#include <algorithm>
+
 namespace parasite {
 
-void BLEAdvertisementData::SetRawSoilMoisture(int raw_soil_moisture) {
-  uint16_t packed_value = raw_soil_moisture;
+void BLEAdvertisementData::SetSoilMoistureRaw(int soil_moisture_raw) {
+  uint16_t packed_value = soil_moisture_raw;
   data_[kRawSoilMoistureOffset] = packed_value >> 8;
   data_[kRawSoilMoistureOffset + 1] = packed_value & 0xff;
 }
 
+void BLEAdvertisementData::SetSoilMoisturePercent(
+    double soil_moisture_percent) {
+  // TODO: 1.0 * MAX is too close to overflow for comfort?
+  uint16_t packed_value = ((1 << 16) - 1) * soil_moisture_percent;
+  data_[kPercentSoilMoistureOffset] = packed_value >> 8;
+  data_[kPercentSoilMoistureOffset + 1] = packed_value & 0xff;
+}
+
+void BLEAdvertisementData::SetBatteryVoltage(double battery_voltage) {
+  uint16_t packed_value = 1000 * battery_voltage;
+  data_[kBatteryVoltageOffset] = packed_value >> 8;
+  data_[kBatteryVoltageOffset + 1] = packed_value & 0xff;
+}
+
 }  // namespace parasite
\ No newline at end of file
diff --git a/code/parasite/lib/parasite/parasite/ble_advertisement_data.h b/code/parasite/lib/parasite/parasite/ble_advertisement_data.h
index a643e3b..c024614 100644
--- a/code/parasite/lib/parasite/parasite/ble_advertisement_data.h
+++ b/code/parasite/lib/parasite/parasite/ble_advertisement_data.h
@@ -8,20 +8,22 @@
 
 namespace parasite {
 
-constexpr size_t kAdvertisementDataLen = 18;
+constexpr size_t kAdvertisementDataLen = 21;
 constexpr size_t kRawSoilMoistureOffset = 14;
 constexpr size_t kPercentSoilMoistureOffset = kRawSoilMoistureOffset + 2;
-constexpr size_t kTemperatureOfsset = kRawSoilMoistureOffset + 4;
+constexpr size_t kBatteryVoltageOffset = kRawSoilMoistureOffset + 4;
 
 class BLEAdvertisementData {
  public:
-  void SetRawSoilMoisture(int raw_soil_moisture);
+  void SetSoilMoistureRaw(int soil_moisture_raw);
+  void SetSoilMoisturePercent(double soil_moisture_percent);
+  void SetBatteryVoltage(double battery_voltage);
   const uint8_t* GetRawData() const { return data_; }
   size_t GetDataLen() const { return kAdvertisementDataLen; }
 
  private:
   uint8_t data_[kAdvertisementDataLen] = {
-      9,  // Length of name.
+      9,  // Length of name + data type.
       BLE_GAP_AD_TYPE_COMPLETE_LOCAL_NAME,
       'P',
       'a',
@@ -31,14 +33,17 @@ class BLEAdvertisementData {
       'i',
       't',
       'e',
-      7,  // Length of the service data.
+      10,  // Length of the service data + data type.
       BLE_GAP_AD_TYPE_SERVICE_DATA,
       0x1a,
-      0x18,  // Environment sensor service UUID.
+      0x18,  // Environment sensor service UUID (0x181a).
       0x00,
-      0x00,  // Raw soil humidity.
+      0x00,  // Raw soil humidity (2 bytes).
+      0x00,
+      0x00,  // Percentage soil humidity (2 bytes).
+      0x00,
+      0x00,  // Battery voltage (2 bytes representing millivolts).
       0x00,
-      0x00,  // Percentage soil humidity.
   };
 };
 
diff --git a/code/parasite/src/main.cpp b/code/parasite/src/main.cpp
index 7ecffc9..6d48401 100644
--- a/code/parasite/src/main.cpp
+++ b/code/parasite/src/main.cpp
@@ -25,10 +25,13 @@ parasite::SoilMonitor soil_monitor(kSoilMonitorAirVal, kSoilMonitorWaterVal,
                                    kSoilAnalogPin);
 
 void updateAdvertisingData(parasite::BLEAdvertiser* advertiser,
-                           const parasite::soil_reading_t& soil_reading) {
+                           const parasite::soil_reading_t& soil_reading,
+                           double battery_voltage) {
   parasite::BLEAdvertisementData data;
 
-  data.SetRawSoilMoisture(soil_reading.raw);
+  data.SetSoilMoistureRaw(soil_reading.raw);
+  data.SetSoilMoisturePercent(soil_reading.parcent);
+  data.SetBatteryVoltage(battery_voltage);
 
   advertiser->SetData(data);
 
@@ -51,8 +54,8 @@ void setup() {
 }
 
 void loop() {
-  double batt_voltage = batt_monitor.Read();
-  Serial.printf("Batt voltage: %f\n", batt_voltage);
+  double battery_voltage = batt_monitor.Read();
+  Serial.printf("Batt voltage: %f\n", battery_voltage);
 
   parasite::soil_reading_t soil_reading = soil_monitor.Read();
   Serial.printf("Moisture val: %d, %f%%\n", soil_reading.raw,
@@ -60,7 +63,7 @@ void loop() {
 
   digitalToggle(kLED1Pin);
 
-  updateAdvertisingData(&advertiser, soil_reading);
+  updateAdvertisingData(&advertiser, soil_reading, battery_voltage);
 
   delay(500);
 }
\ No newline at end of file