Electron I2C connection problems when using SLEEP_NETWORK_STANDBY

Firmware
1

I have an Electron and connected the HTU21D temp and humidity sensor to it directly on the D0 and D1 pins.

When I run the sample sketch from https://build.particle.io/libs/53edeb4ccf314539c90003a4/tab/HTU21D.ino then it all works fine, but as soon as I use SLEEP_NETWORK_STANDBY to put the Electron to sleep, then the HTU21D reports 998 values - which is the equivalent of I2C connection errors. Even if after each sleep I use:

while(! htu.begin()){ Serial.println("HTU21D not found"); delay(1000); }

If I use normal sleep (which restarts), then it works.

See code below.

The sample sketch of HTU21D with normal sleep - which sleeps restarts and reconnects to the cloud at each iteration - works, at each iteration it reads the correct values from the HTU21D:

    #include "HTU21D/HTU21D.h"
    
    HTU21D htu = HTU21D();
    
    void setup()
    {
    	Serial.begin(9600);
    
    	Serial.println("HTU21D test");
    
    	while(! htu.begin()){
    	    Serial.println("HTU21D not found");
    	    delay(1000);
    	}
    
    	Serial.println("HTU21D OK");
    }
    
    void loop()
    {
    	Serial.println("===================");
    	Serial.print("Hum:"); Serial.println(htu.readHumidity());
    	Serial.print("Temp:"); Serial.println(htu.readTemperature());
    	Serial.println();
    
    	delay(1000);
    
        Particle.publish("L", String::format("2.1,2.22,2.22,%2.2f,%2.2f,1", htu.readHumidity(),htu.readTemperature()));
    	System.sleep(D1, RISING, 10);
    }

But when using the SLEEP_NETWORK_STANDBY then only the first reading of HTU21D shows the right values, then it shows 998 for each reading

    #include "HTU21D/HTU21D.h"
    
    HTU21D htu = HTU21D();
    
    void setup()
    {
    	Serial.begin(9600);
    
    	Serial.println("HTU21D test");
    
    	while(! htu.begin()){
    	    Serial.println("HTU21D not found");
    	    delay(1000);
    	}
    
    	Serial.println("HTU21D OK");
    }
    
    void loop()
    {
    	Serial.println("===================");
    	Serial.print("Hum:"); Serial.println(htu.readHumidity());
    	Serial.print("Temp:"); Serial.println(htu.readTemperature());
    	Serial.println();
    
    	delay(1000);
    
        Particle.publish("L", String::format("2.1,2.22,2.22,%2.2f,%2.2f,1", htu.readHumidity(),htu.readTemperature()));
    	System.sleep(D1, RISING, 10, SLEEP_NETWORK_STANDBY);

        while(! htu.begin()){ Serial.println("HTU21D not found"); delay(1000); }
    }

This seems to indicate that the SLEEP_NETWORK_STANDBY breaks I2C.

Any suggestions?

2

Can you try calling Wire.begin(); after System.sleep(D1, RISING, 10, SLEEP_NETWORK_STANDBY); but before the loop calling htu.begin()? That would help rule out one possible problem.

1 Like
3

Thanks, yes, that seems to have solved it!!!
Still testing it, but so far so good.

1 Like