Arduino Nano V3 only runs sketch correctly after hitting reset or starting serial monitor

Projects Programming
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  • VCC pin from both sensors to either 3.3V or 5V. If you are using an Arduino Uno, use the 5V pin.
  • GND pin from both sensors to the GND pin on Arduino.
  • SCK pin from both sensors to the I2C clock SCL pin 28 on Arduino nano. On the Arduino Uno that would be the pin A5.
  • SDI pin from both sensors to the I2C data SDA pin 27 on Arduino nano. On the Arduino Uno that would be the pin A4.
  • Leave the CS pin from both sensors unconnected.
  • Leave the SDO pin from only one sensor unconnected.
  • Connect the SDO pin from the other sensor to GND.
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All tried, USB from PC, works only after reset or openning serial monitor.

12V 1A to the vin pins same situation.

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I didnt know what Pullups are, I have taken a look and they make sense now! I think the bluedot board has them on.

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SOLVED!

So I have placed a cap between rst and gnd, to be able to enter the serial monitor without triggering the reset that would restart and correct the issue. I have noticed that the correction value is calculated way too high. that was a direct pointer that at the moment of the calculation one sensor is way off. I have added a delay between the sensor reading and the calculation of the correction, and that solved it. I have accurate measurements and functionality on all power sources with power cycling of different intervals.

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@Whandall Many thanks, I have learned from you what state machine programming is, I will convert my code to one, it will be simpler.

@TomGeorge Many thanks to you as well! you made me learn pullups and pulldowns. Very interesting.

Regards,
Rami

1 Like
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