From 35e1c401e2f6b041a87546c44f3f79fd624c33d4 Mon Sep 17 00:00:00 2001
From: Tom Fifield <tom@tomfifield.net>
Date: Wed, 18 Sep 2024 23:12:49 +0800
Subject: [PATCH] PMSA0031 sensors require ~3secs before coming up on I2C
 (#4743)
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* PMSA0031 sensors require ~3secs before coming up on I2C

As reported by @MALAONE1 and debugged by @shodan8192 , PMSA0031s
on a RAK4631 take 3 seconds before they can become detectable on I2c.

Add a delay(4000) before I2C scan if the air quality sensor pin
is defined.

Fixes https://github.com/meshtastic/firmware/issues/3690

* Remove 4 second wait and rescan during air quality init for the sensor

* works without but this triggers my OCD

---------

Co-authored-by: Thomas Göttgens <tgoettgens@gmail.com>
Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
---
 src/main.cpp                                  |  4 +--
 src/modules/Telemetry/AirQualityTelemetry.cpp | 25 +++++++++++++++----
 src/modules/Telemetry/AirQualityTelemetry.h   |  2 +-
 3 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index a6e6ad631..e24ba68b3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -390,7 +390,7 @@ void setup()
 #endif
 
 #ifdef AQ_SET_PIN
-    // RAK-12039 set pin for Air quality sensor
+    // RAK-12039 set pin for Air quality sensor. Detectable on I2C after ~3 seconds, so we need to rescan later
     pinMode(AQ_SET_PIN, OUTPUT);
     digitalWrite(AQ_SET_PIN, HIGH);
 #endif
@@ -1142,4 +1142,4 @@ void loop()
     }
     // if (didWake) LOG_DEBUG("wake!\n");
 }
-#endif
+#endif
\ No newline at end of file
diff --git a/src/modules/Telemetry/AirQualityTelemetry.cpp b/src/modules/Telemetry/AirQualityTelemetry.cpp
index d07296710..56d308cfa 100644
--- a/src/modules/Telemetry/AirQualityTelemetry.cpp
+++ b/src/modules/Telemetry/AirQualityTelemetry.cpp
@@ -10,11 +10,11 @@
 #include "PowerFSM.h"
 #include "RTC.h"
 #include "Router.h"
+#include "detect/ScanI2CTwoWire.h"
 #include "main.h"
 
 int32_t AirQualityTelemetryModule::runOnce()
 {
-    int32_t result = INT32_MAX;
     /*
         Uncomment the preferences below if you want to use the module
         without having to configure it from the PythonAPI or WebUI.
@@ -29,21 +29,36 @@ int32_t AirQualityTelemetryModule::runOnce()
 
     if (firstTime) {
         // This is the first time the OSThread library has called this function, so do some setup
-        firstTime = 0;
+        firstTime = false;
 
         if (moduleConfig.telemetry.air_quality_enabled) {
             LOG_INFO("Air quality Telemetry: Initializing\n");
             if (!aqi.begin_I2C()) {
-                LOG_WARN("Could not establish i2c connection to AQI sensor\n");
+                LOG_WARN("Could not establish i2c connection to AQI sensor. Rescanning...\n");
+                // rescan for late arriving sensors. AQI Module starts about 10 seconds into the boot so this is plenty.
+                uint8_t i2caddr_scan[] = {PMSA0031_ADDR};
+                uint8_t i2caddr_asize = 1;
+                auto i2cScanner = std::unique_ptr<ScanI2CTwoWire>(new ScanI2CTwoWire());
+#if defined(I2C_SDA1)
+                i2cScanner->scanPort(ScanI2C::I2CPort::WIRE1, i2caddr_scan, i2caddr_asize);
+#endif
+                i2cScanner->scanPort(ScanI2C::I2CPort::WIRE, i2caddr_scan, i2caddr_asize);
+                auto found = i2cScanner->find(ScanI2C::DeviceType::PMSA0031);
+                if (found.type != ScanI2C::DeviceType::NONE) {
+                    nodeTelemetrySensorsMap[meshtastic_TelemetrySensorType_PMSA003I].first = found.address.address;
+                    nodeTelemetrySensorsMap[meshtastic_TelemetrySensorType_PMSA003I].second =
+                        i2cScanner->fetchI2CBus(found.address);
+                    return 1000;
+                }
                 return disable();
             }
             return 1000;
         }
-        return result;
+        return disable();
     } else {
         // if we somehow got to a second run of this module with measurement disabled, then just wait forever
         if (!moduleConfig.telemetry.air_quality_enabled)
-            return result;
+            return disable();
 
         uint32_t now = millis();
         if (((lastSentToMesh == 0) ||
diff --git a/src/modules/Telemetry/AirQualityTelemetry.h b/src/modules/Telemetry/AirQualityTelemetry.h
index 23df6ac58..fb8edd07e 100644
--- a/src/modules/Telemetry/AirQualityTelemetry.h
+++ b/src/modules/Telemetry/AirQualityTelemetry.h
@@ -44,7 +44,7 @@ class AirQualityTelemetryModule : private concurrency::OSThread, public Protobuf
   private:
     Adafruit_PM25AQI aqi;
     PM25_AQI_Data data = {0};
-    bool firstTime = 1;
+    bool firstTime = true;
     meshtastic_MeshPacket *lastMeasurementPacket;
     uint32_t sendToPhoneIntervalMs = SECONDS_IN_MINUTE * 1000; // Send to phone every minute
     uint32_t lastSentToMesh = 0;