Red status LED 'SOS' hard fault

Troubleshooting
1

I’ll keep it short. I bought a Xenon, Argon and a temperature Sensor.

Coding the Xenon:

I accessed the temperaturevalue via Particle.function and Particle.variable with an empty loop and everything worked perfectly.
I did some changes to the code so the Argon could subscribe to the value.
Now the Xenon is dead.
I don’t want to kill another Xenon, it would help me alot if some smart talented guy could tell me where the small mistake is.

SYSTEM_THREAD(ENABLED);
/*SYSTEM_MODE(MANUAL)*/ //buggy

#include "math.h"
#include "stdio.h"

#define LM75_ADDRESS 0x48 
#define LM75_TEMPERATURE 0x00
#define LM75_CONFIGURATION 0x01
#define LM75_Tos_SET_POINT 0x02
#define LM75_Thyst_SET_POINT 0x03

int led1 = D7;

uint16_t test = 0b1000000000000001;
double TemperatureValue = test;
char buffer[100];

void setup() {
pinMode(led1, OUTPUT);
//Particle.function("ReadTemperature", ReadTemperature);
//Particle.variable("Temperatur", TemperatureValue);
Wire.begin();
}

void loop() {
    float temp = ReadTemperature();
    snprintf(buffer, sizeof(buffer), "Temp is %f", temp);
    Particle.publish("temp", buffer);
    delay(5000);
}

float ReadTemperature(){
    Wire.beginTransmission(LM75_ADDRESS);
    Wire.write(LM75_TEMPERATURE);
    Wire.endTransmission();
    
    uint16_t val = 0;
    uint16_t val2 = 0;
        
    Wire.requestFrom(LM75_ADDRESS, 2);
    val = Wire.read();
    val <<= 1;
    val2 = Wire.read();
    val2 >>= 7;
    val = val|val2;

    TemperatureValue = val/2;
    return TemperatureValue;
}
2

How did your Xenon connect to the cloud without a gateway?
How would any changes on the Argon contribute to the "death" of your Xenon?

But one thing smells here :wink:
You have a Particle.publish() (which you should actually limit the scope to PRIVATE) which may be executed before you have a valid cloud connection (due to SYSTEM_THREAD(ENABLED)).
When you wrap that publish with an if (Particle.connected()) check then at least this problem should go away.

BTW, why would you consider SYSTEM_MODE(MANUAL) buggy?

3

Okay, I limited the scope of Particle.publish to private. I did not know "SYSTEM_THREAD(ENABLED)" does this.
Your solution is very helpful, thanks for your comment.
I will remember you helped me on this ScruffR.

1 Like
4

Did this solve your problem?

With this your code will start running immediately independent of the connection status.
https://docs.particle.io/reference/device-os/firmware/xenon/#system-threading-behavior

5

I am too scared to test the changed code on another device, I don't want to break 2 of them.
I will test it when I know the "exact" reason with the changes you suggested. Then I will inform you about it ScruffR.

Thanks ScruffR, I will read the page you sent me.

6

How do you know this? What temperature sensor did you use?

7

I cannot access another mode except dfu.
I tried flashing a user Firmware onto the Xenon like it is explained in this infopage:
https://docs.particle.io/tutorials/device-os/led/argon/#firmware-reset

I used the temperature sensor lm75 with I2C interface

8

So put the device into DFU - Flashing Yellow.

Then from the CLI enter
particle update

This should restore the OS, then back to DFU mode and enter
particle flash --usb tinker

let it restart and you should have flashing green - or if it is part of a mesh and the gateway is active and connected, it will shortly then transition to breathing cyan.

Let us know what happens

9

This also the link for restoring an ARGON not the XENON you speak about ?

10

I did execute the steps you suggested and it worked, the Xenon is now functionally again.
After execution the Xenon was in listening mode.
I let him join the mesh network and it worked.

This should be posted on the infopage as general solution.