Hardware Issues/ Enhancements

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• Upgrade from 200mA LDO to 500mA LDO solved my RESET issue.

  • Now using TC1262-3.3V LDO

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  Status
  colour Green title ENHANCEMENT

  Hall Effect sensors on measurement devices
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  Status
  colour Green title ENHANCEMENT

  I2C based counters for rainfall and wind anemometer revolution count
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  Status
  colour Green title Enhancement

  Full low current analysis
•  Mount ESP32 on PCB and keep only what I need in the design

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•  Hall Effect sensor based wind and rainfall measurement
•  I2C based wind counter, easier to periodically read instantaneous wind values with ULP
•  Layout ESP32 on main PCB, get rid of the dev module entirely
•  Really attack the deep sleep current support
•  Add FET switch for powering down all peripherals while in deep sleep
•  No power LED constantly drawing current
•  LoRaWAN stack
•  

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08 Jul 2021 New LDO works great! Very haphazardly tacked on the existing PCB design, but no more brownout and RESET.

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Battery Life Testing

Using a 3100mA LiIon cell

08 Jul 2021 6am, battery testing with 15min timer settings to evaluate battery life with no recharge

11 Jul 2021 4am battery voltage falls < 3.7V

Current Measurement

DEV board and deep sleep current capabilities are not compatible with each other

Thomas was able to get sleep current <1mA when removing the power LED and the USB to UART converter chip.

New PCB arrived

04 Aug 2021 Thomas designed a PCB version that accepts the new LDO. I’ve been examining the new board and experimenting with it.

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09 Aug 2021

NVM rainfall backup looking more appealing every day.

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10 Aug 2021

Disappointed that I’m seeing RESETs, but found something in my code

  //Average samples
  if (msTotal || samples)
  {
    windSpeed = 1.49 * 1000 / (msTotal / samples);
  }

My logic to check for divide by zero is wrong. Should be &&

  //Average samples
  if (msTotal && samples)
  {
    windSpeed = 1.49 * 1000 / (msTotal / samples);
  }

Running boot experiment without sensor connected now. msTotal and samples will both be zero and this case will never happen.

After running 1000 boot cycles without incident, I’ve proven to myself that the secondary RESET issue was caused by software.

11 Aug 2021

Now at 1800 boot count with no issues. Hardware is stable.

Image Added

14 Aug 2021

Secondary, intermittent reset issue seems to be solved by properly marking ISR routines to be copied to SRAM.

IRAM_ATTR in function definition informs program to copy and execute code from SRAM.

//=======================================================
//  windTick: ISR to capture wind speed relay closure
//=======================================================
void IRAM_ATTR windTick(void)
{
  timeSinceLastTick = millis() - lastTick;
  //software debounce attempt
  //record up to 10 ticks from anemometer
  if (timeSinceLastTick > 10 && count < 10)
  {
    lastTick = millis();
    tickTime[count] = timeSinceLastTick;
    count++;
  }
}