Add battery sensing (mostly) for TBEAM0.7

However, disabled until someone with suitable hardware can test and report
back.

@slavino and @tschundler would you be willing to try it with your boards?

You'll need to uncomment the following line in configuration.h

// #define BATTERY_PIN 35 // A battery voltage measurement pin, voltage divider connected here to measure battery voltage

platformio.ini

@@ -69,6 +69,7 @@ lib_deps =
   https://github.com/meshtastic/SparkFun_Ublox_Arduino_Library.git
   https://github.com/meshtastic/RadioLib.git#d6b12f7eb0a06bd2414c79b437b25d377e3f603f
   https://github.com/meshtastic/TinyGPSPlus.git 
+  https://github.com/meshtastic/AXP202X_Library.git#8404abb6d4b486748636bc6ad72d2a47baaf5460
 
 ; Common settings for ESP targes, mixin with extends = esp32_base
 [esp32_base]
@@ -99,7 +100,6 @@ extends = esp32_base
 board = ttgo-t-beam
 lib_deps =
   ${env.lib_deps}
-  https://github.com/meshtastic/AXP202X_Library.git
 build_flags = 
   ${esp32_base.build_flags} -D TBEAM_V10
 

src/Power.cpp

@@ -1,27 +1,92 @@
 #include "power.h"
 #include "PowerFSM.h"
 #include "main.h"
-#include "utils.h"
 #include "sleep.h"
-
+#include "utils.h"
-#ifdef TBEAM_V10
 
 // FIXME. nasty hack cleanup how we load axp192
 #undef AXP192_SLAVE_ADDRESS
 #include "axp20x.h"
+
+#ifdef TBEAM_V10
 AXP20X_Class axp;
+#endif
+
 bool pmu_irq = false;
 
 Power *power;
 
+/**
+ * If this board has a battery level sensor, set this to a valid implementation
+ */
+static HasBatteryLevel *batteryLevel; // Default to NULL for no battery level sensor
+
+/**
+ * A simple battery level sensor that assumes the battery voltage is attached via a voltage-divider to an analog input
+ */
+class AnalogBatteryLevel : public HasBatteryLevel
+{
+    /**
+     * Battery state of charge, from 0 to 100 or -1 for unknown
+     *
+     * FIXME - use a lipo lookup table, the current % full is super wrong
+     */
+    virtual int getBattPercentage()
+    {
+        float v = getBattVoltage();
+
+        if (v < 2.1)
+            return -1;
+
+        return 100 * (getBattVoltage() - 3.27) / (4.2 - 3.27);
+    }
+
+    /**
+     * The raw voltage of the battery or NAN if unknown
+     */
+    virtual float getBattVoltage()
+    {
+        return
+#ifdef BATTERY_PIN
+            analogRead(BATTERY_PIN) * 2.0 * (3.3 / 1024.0);
+#else
+            NAN;
+#endif
+    }
+
+    /**
+     * return true if there is a battery installed in this unit
+     */
+    virtual bool isBatteryConnect() { return true; }
+} analogLevel;
+
+bool Power::analogInit()
+{
+#ifdef BATTERY_PIN
+    DEBUG_MSG("Using analog input for battery level\n");
+    adcAttachPin(BATTERY_PIN);
+    // adcStart(BATTERY_PIN);
+    analogReadResolution(10); // Default of 12 is not very linear. Recommended to use 10 or 11 depending on needed resolution.
+    batteryLevel = &analogLevel;
+    return true;
+#else
+    return false;
+#endif
+}
+
 bool Power::setup()
 {
+    bool found = axp192Init();
 
-    axp192Init();
+    if (!found) {
+        found = analogInit();
+    }
+    if (found) {
         concurrency::PeriodicTask::setup(); // We don't start our periodic task unless we actually found the device
         setPeriod(1);
+    }
 
-    return axp192_found;
+    return found;
 }
 
 /// Reads power status to powerStatus singleton.
@@ -29,30 +94,35 @@ bool Power::setup()
 // TODO(girts): move this and other axp stuff to power.h/power.cpp.
 void Power::readPowerStatus()
 {
-    bool hasBattery = axp.isBatteryConnect();
+    if (batteryLevel) {
+        bool hasBattery = batteryLevel->isBatteryConnect();
         int batteryVoltageMv = 0;
         uint8_t batteryChargePercent = 0;
         if (hasBattery) {
-        batteryVoltageMv = axp.getBattVoltage();
+            batteryVoltageMv = batteryLevel->getBattVoltage();
             // If the AXP192 returns a valid battery percentage, use it
-        if (axp.getBattPercentage() >= 0) {
+            if (batteryLevel->getBattPercentage() >= 0) {
-            batteryChargePercent = axp.getBattPercentage();
+                batteryChargePercent = batteryLevel->getBattPercentage();
             } else {
                 // If the AXP192 returns a percentage less than 0, the feature is either not supported or there is an error
-            // In that case, we compute an estimate of the charge percent based on maximum and minimum voltages defined in power.h
+                // In that case, we compute an estimate of the charge percent based on maximum and minimum voltages defined in
-            batteryChargePercent = clamp((int)(((batteryVoltageMv - BAT_MILLIVOLTS_EMPTY) * 1e2) / (BAT_MILLIVOLTS_FULL - BAT_MILLIVOLTS_EMPTY)), 0, 100);
+                // power.h
+                batteryChargePercent =
+                    clamp((int)(((batteryVoltageMv - BAT_MILLIVOLTS_EMPTY) * 1e2) / (BAT_MILLIVOLTS_FULL - BAT_MILLIVOLTS_EMPTY)),
+                          0, 100);
             }
         }
 
         // Notify any status instances that are observing us
-    const meshtastic::PowerStatus powerStatus = meshtastic::PowerStatus(hasBattery, axp.isVBUSPlug(), axp.isChargeing(), batteryVoltageMv, batteryChargePercent);
+        const meshtastic::PowerStatus powerStatus = meshtastic::PowerStatus(
+            hasBattery, batteryLevel->isVBUSPlug(), batteryLevel->isChargeing(), batteryVoltageMv, batteryChargePercent);
         newStatus.notifyObservers(&powerStatus);
 
         // If we have a battery at all and it is less than 10% full, force deep sleep
-    if (powerStatus.getHasBattery() && !powerStatus.getHasUSB() &&
+        if (powerStatus.getHasBattery() && !powerStatus.getHasUSB() && batteryLevel->getBattVoltage() < MIN_BAT_MILLIVOLTS)
-        axp.getBattVoltage() < MIN_BAT_MILLIVOLTS)
             powerFSM.trigger(EVENT_LOW_BATTERY);
     }
+}
 
 void Power::doTask()
 {
@@ -62,9 +132,7 @@ void Power::doTask()
     if (statusHandler && statusHandler->isInitialized())
         setPeriod(1000 * 20);
 }
-#endif // TBEAM_V10
 
-#ifdef AXP192_SLAVE_ADDRESS
 /**
  * Init the power manager chip
  *
@@ -74,10 +142,13 @@ void Power::doTask()
  30mA -> charges GPS backup battery // charges the tiny J13 battery by the GPS to power the GPS ram (for a couple of days), can
  not be turned off LDO2 200mA -> LORA LDO3 200mA -> GPS
  */
-void Power::axp192Init()
+bool Power::axp192Init()
 {
+#ifdef TBEAM_V10
     if (axp192_found) {
         if (!axp.begin(Wire, AXP192_SLAVE_ADDRESS)) {
+            batteryLevel = &axp;
+
             DEBUG_MSG("AXP192 Begin PASS\n");
 
             // axp.setChgLEDMode(LED_BLINK_4HZ);
@@ -135,12 +206,16 @@ void Power::axp192Init()
     } else {
         DEBUG_MSG("AXP192 not found\n");
     }
-}
+
+    return axp192_found;
+#else
+    return false;
 #endif
+}
+
 
 void Power::loop()
 {
-
 #ifdef PMU_IRQ
     if (pmu_irq) {
         pmu_irq = false;
@@ -174,6 +249,5 @@ void Power::loop()
         axp.clearIRQ();
     }
 
-#endif // T_BEAM_V10
+#endif
-
 }

src/configuration.h

@@ -167,7 +167,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 // Leave undefined to disable our PMU IRQ handler
 #define PMU_IRQ 35
-
 #define AXP192_SLAVE_ADDRESS 0x34
 
 #elif defined(TBEAM_V07)
@@ -180,6 +179,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define I2C_SCL 22
 
 #define BUTTON_PIN 39
+// #define BATTERY_PIN 35 // A battery voltage measurement pin, voltage divider connected here to measure battery voltage
 
 #ifndef USE_JTAG
 #define RF95_RESET 23
@@ -278,6 +278,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define GPS_RX_PIN 36
 #define GPS_TX_PIN 39
 
+// #define BATTERY_PIN 35 // A battery voltage measurement pin, voltage divider connected here to measure battery voltage
+
 #define I2C_SDA 21 // I2C pins for this board
 #define I2C_SCL 22
 

src/main.cpp

@@ -210,13 +210,11 @@ void setup()
     esp32Setup();
 #endif
 
-#ifdef TBEAM_V10
     // Currently only the tbeam has a PMU
     power = new Power();
     power->setup();
     power->setStatusHandler(powerStatus);
     powerStatus->observe(&power->newStatus);
-#endif
 
 #ifdef NRF52_SERIES
     nrf52Setup();

src/power.h

@@ -1,6 +1,6 @@
 #pragma once
-#include "concurrency/PeriodicTask.h"
 #include "PowerStatus.h"
+#include "concurrency/PeriodicTask.h"
 
 /**
  * Per @spattinson
@@ -19,22 +19,22 @@ class Power : public concurrency::PeriodicTask
 {
 
   public:
-
     Observable<const meshtastic::PowerStatus *> newStatus;
 
     void readPowerStatus();
     void loop();
     virtual bool setup();
     virtual void doTask();
-    void setStatusHandler(meshtastic::PowerStatus *handler)
+    void setStatusHandler(meshtastic::PowerStatus *handler) { statusHandler = handler; }
-    {
-        statusHandler = handler;
-    }
 
   protected:
     meshtastic::PowerStatus *statusHandler;
-    virtual void axp192Init();
 
+    /// Setup a axp192, return true if found
+    bool axp192Init();
+
+    /// Setup a simple ADC input based battery sensor
+    bool analogInit();
 };
 
 extern Power *power;