fix: account for MAX17043 alert status on start (arendst#19708)

tasmota/include/i18n.h

@@ -238,6 +238,7 @@
 #define D_JSON_MY "YaxisInduction"
 #define D_JSON_MZ "ZaxisInduction"
 #define D_JSON_MAGNETICFLD "MagneticInduction"
+#define D_JSON_ALERT "Alert"
 #define D_JSON_BATTPERCENT "BatteryPercentage"
 #define D_RSLT_ENERGY "ENERGY"
 #define D_RSLT_HASS_STATE "HASS_STATE"

tasmota/my_user_config.h

@@ -716,6 +716,7 @@
 //    #define TC74_MAX_FAILCOUNT 8                 // Maximum failed polls before it's marked inactive until reprobing later
 //  #define USE_PCA9557                            // [I2cDriver81] Enable PCA9557 8-bit I/O Expander (I2C addresses 0x18 - 0x1F) (+2k5 code)
 //  #define USE_MAX17043                           // [I2cDriver83] Enable MAX17043 fuel-gauge systems Lipo batteries sensor (I2C address 0x36) (+0k9 code)
+//  #define MAX17043_ALERT_THRESHOLD 32            // [I2cDriver83] Define the alert threshold for low battery level percentage 1-32
 
 //  #define USE_RTC_CHIPS                          // Enable RTC chip support and NTP server - Select only one
 //    #define USE_DS3231                           // [I2cDriver26] Enable DS3231 RTC (I2C address 0x68) (+1k2 code)

tasmota/tasmota_xsns_sensor/xsns_110_max17043.ino

@@ -25,8 +25,11 @@
  *
  * Battery voltage in Volt and State Of Charge (SOC) in percent are published via MQTT
  * 
- * The alert flag and alert threshold are not required for MQTT, the alert pin is not used 
- * by this sensor driver.
+ * The alert flag and alert threshold have been added to this sensor driver. Use
+ * Alert via as a 'low battery' or 'battery critical' binary sensor
+ * 
+ * set MAX17043_ALERT_THRESHOLD to a percentage between 1-32 in my_user_config.h
+ * default is 32% per the legacy of this driver
  * 
  * Tested module(s):
  * 
@@ -53,26 +56,43 @@
 
 #define MAX17043_MODE_COMMAND_POWERONRESET  0x5400
 #define MAX17043_MODE_COMMAND_QUICKSTART    0x4000
-#define MAX17043_CONFIG_POWER_UP_DEFAULT    0x971c
-#define MAX17043_CONFIG_NO_COMPENSATION     0x9700
+#define MAX17043_CONFIG_POWER_UP_DEFAULT    0x971C
+#define MAX17043_CONFIG_SAFE_MASK           0xFF1F  // mask out sleep bit (7), unused bit (6) and alert bit (4)
+#define MAX17043_CONFIG_ALERT_MASK          0x0020  // mask alert bit (4)
+
+#ifndef MAX17043_ALERT_THRESHOLD
+#define MAX17043_ALERT_THRESHOLD    32   // legacy sensor code set this to 32%
+#endif
+#if MAX17043_ALERT_THRESHOLD<1
+#undef MAX17043_ALERT_THRESHOLD
+#define MAX17043_ALERT_THRESHOLD    1
+#endif
+#if MAX17043_ALERT_THRESHOLD>32
+#undef MAX17043_ALERT_THRESHOLD
+#define MAX17043_ALERT_THRESHOLD    32
+#endif
 
 bool max17043 = false;
 int battery_latest = 101;
 
+// set the lower 5 bits of config register to the 2's complement of MAX17043_ALERT_THRESHOLD
+const uint16_t config_with_threshold = (MAX17043_CONFIG_POWER_UP_DEFAULT & 0xFFE0) | ((~MAX17043_ALERT_THRESHOLD+1) & 0x001F);
+
 /*********************************************************************************************/
 
 void Max17043Init(void) {
+  uint16_t config_reg;
   if (I2cSetDevice(MAX17043_ADDRESS)) { 
     if (REASON_DEEP_SLEEP_AWAKE == ESP_ResetInfoReason()) {
       // if waking from deep sleep we assume the hardware design maintained power to the MAX17043
       // retaining its model of the internal dynamics the battery
-      // if the hardware design doesn't (to conserve battery) then we lose some of
+      // if the hardware design doesn't (to conserve battery) then we lose many of
       // the benefits of the device anyway as it'll be re-learning from scratch every DeepSleepTime seconds.
 
-      // to confirm this is a MAX17043 - check for both the default (if the MAX17043 did lose it's power)
-      // or our setting if power was maintained
-      if (I2cRead16(MAX17043_ADDRESS, MAX17043_CONFIG) == MAX17043_CONFIG_NO_COMPENSATION
-          || I2cRead16(MAX17043_ADDRESS, MAX17043_CONFIG) == MAX17043_CONFIG_POWER_UP_DEFAULT) {
+      // confirm this is a MAX17043
+      // mask out unpredictable bits on the config register
+      config_reg = I2cRead16(MAX17043_ADDRESS, MAX17043_CONFIG) & MAX17043_CONFIG_SAFE_MASK;
+      if (config_reg == MAX17043_CONFIG_POWER_UP_DEFAULT || config_reg == config_with_threshold) {
         max17043 = true;
         I2cSetActiveFound(MAX17043_ADDRESS, MAX17043_NAME);
         AddLog(LOG_LEVEL_DEBUG_MORE, PSTR("SNS: Waking from deep sleep - skipping " MAX17043_NAME " Power on Reset & Quick Start"));
@@ -83,12 +103,16 @@ void Max17043Init(void) {
 
       I2cWrite16(MAX17043_ADDRESS, MAX17043_COMMAND, MAX17043_MODE_COMMAND_POWERONRESET);
       delay(10);
-      if (I2cRead16(MAX17043_ADDRESS, MAX17043_CONFIG) == MAX17043_CONFIG_POWER_UP_DEFAULT) {  // Read the default to confirm this is a MAX17043
+      // confirm this is a MAX17043 (must read after power on reset, as reset does just that to the config register)
+      // mask out unpredictable bits on the config register
+      config_reg = I2cRead16(MAX17043_ADDRESS, MAX17043_CONFIG) & MAX17043_CONFIG_SAFE_MASK;
+      if (config_reg == MAX17043_CONFIG_POWER_UP_DEFAULT) {
         I2cWrite16(MAX17043_ADDRESS, MAX17043_MODE, MAX17043_MODE_COMMAND_QUICKSTART);    
-        I2cWrite16(MAX17043_ADDRESS, MAX17043_CONFIG, MAX17043_CONFIG_NO_COMPENSATION);
+        I2cWrite16(MAX17043_ADDRESS, MAX17043_CONFIG, config_with_threshold);
         delay(10);
         max17043 = true;
         I2cSetActiveFound(MAX17043_ADDRESS, MAX17043_NAME);
+        AddLog(LOG_LEVEL_DEBUG_MORE, PSTR("SNS: " MAX17043_NAME " Alert Threshold set to %d" D_UNIT_PERCENT), MAX17043_ALERT_THRESHOLD);
       }
     }
   }
@@ -100,6 +124,7 @@ void Max17043Show(bool json) {
   uint16_t per = I2cRead16(MAX17043_ADDRESS, MAX17043_SOC);
   float percentage = (float)((per >> 8) + 0.003906f * (per & 0x00ff));  // Battery remaining charge in percent
   int battery_current;
+  bool alert = (MAX17043_CONFIG_ALERT_MASK == (I2cRead16(MAX17043_ADDRESS, MAX17043_CONFIG) & MAX17043_CONFIG_ALERT_MASK));
 
   // During charging the percentage might be (slightly) above 100%. To avoid strange numbers
   // in the statistics the percentage provided by this driver will not go above 100%
@@ -112,7 +137,7 @@ void Max17043Show(bool json) {
     battery_latest = battery_current;
   }
   if (json) {
-    ResponseAppend_P(PSTR(",\"" MAX17043_NAME "\":{\"" D_JSON_VOLTAGE "\":%3_f,\"" D_JSON_BATTPERCENT "\":%2_f}"), &voltage, &percentage );
+    ResponseAppend_P(PSTR(",\"" MAX17043_NAME "\":{\"" D_JSON_VOLTAGE "\":%3_f,\"" D_JSON_BATTPERCENT "\":%2_f, \"" D_JSON_ALERT "\":%d}"), &voltage, &percentage, alert);    
 #ifdef USE_WEBSERVER
   } else {
     WSContentSend_PD(PSTR("{s}" MAX17043_NAME " " D_VOLTAGE "{m}%1_f" D_UNIT_VOLT "{e}"), &voltage);