Random wanderings through Microsoft Azure esp. the IoT bits, AI on Micro controllers, .NET nanoFramework, .NET Core on *nix, and GHI Electronics TinyCLR
The voltage my test setup was calculating looked wrong, then I realised that the sample calculation in the RAK Wireless forums wasn’t applicable to my setup.
I updated the formula used to calculate the battery voltage and deployed the application
public static void Main()
{
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} devMobile.IoT.RAK.Wisblock.AzureIoTHub.RAK11200.PowerSleep starting");
Thread.Sleep(5000);
try
{
double batteryVoltage;
Configuration.SetPinFunction(Gpio.IO04, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.I2C1_CLOCK);
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Battery voltage measurement");
// Configure Analog input (AIN0) port then read the "battery charge"
AdcController adcController = new AdcController();
using (AdcChannel batteryVoltageAdcChannel = adcController.OpenChannel(AdcControllerChannel))
{
batteryVoltage = batteryVoltageAdcChannel.ReadValue() / 723.7685;
Debug.WriteLine($" BatteryVoltage {batteryVoltage:F2}");
if (batteryVoltage < Config.BatteryVoltageBrownOutThreshold)
{
Sleep.EnableWakeupByTimer(Config.FailureRetryInterval);
Sleep.StartDeepSleep();
}
}
catch (Exception ex)
{
...
}
To test the accuracy of the voltage calculation I am going to run my setup on the office windowsill for a week regularly measuring the voltage. Then, turn the solar panel over (so the battery is not getting charged) and monitor the battery discharging until the RAK11200 WisBlock WiFi Module won’t connect to the network.
After some “tinkering” I found the voltage calculation was surprisingly accurate (usually within 0.01V) for my RAK19001 and RAK19007 base boards.
When the battery voltage was close to its minimum working voltage of the ESP32 device it would reboot when the WifiNetworkHelper.ConnectDhcp method was called. This would quickly drain the battery flat even when the solar panel was trying to charge the battery.
Now, before trying to connect to the wireless network the battery voltage is checked and if too low (more experimentation required) the device goes into a deep sleep for a configurable period (more experimentation required). This is so the solar panel can charge the battery to a level where wireless connectivity will work.
public static void Main()
{
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} devMobile.IoT.RAK.Wisblock.AzureIoTHub.RAK11200.PowerSleep starting");
Thread.Sleep(5000);
try
{
Configuration.SetPinFunction(Gpio.IO04, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.I2C1_CLOCK);
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Wifi connecting");
if (!WifiNetworkHelper.ConnectDhcp(Config.Ssid, Config.Password, requiresDateTime: true))
{
if (NetworkHelper.HelperException != null)
{
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} WifiNetworkHelper.ConnectDhcp failed {NetworkHelper.HelperException}");
}
Sleep.EnableWakeupByTimer(Config.FailureRetryInterval);
Sleep.StartDeepSleep();
}
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Wifi connected");
// Configure the SHTC3
I2cConnectionSettings settings = new(I2cDeviceBusID, Shtc3.DefaultI2cAddress);
I2cDevice device = I2cDevice.Create(settings);
Shtc3 shtc3 = new(device);
// Assuming that if TryGetTemperatureAndHumidity fails accessing temperature or relativeHumidity will cause an exception
shtc3.TryGetTemperatureAndHumidity(out var temperature, out var relativeHumidity);
#if SLEEP_SHT3C
shtc3.Sleep();
#endif
// Configure Analog input (AIN0) port then read the "battery charge"
AdcController adcController = new AdcController();
AdcChannel batteryChargeAdcChannel = adcController.OpenChannel(AdcControllerChannel);
double batteryCharge = batteryChargeAdcChannel.ReadRatio() * 100.0;
Debug.WriteLine($" Temperature {temperature.DegreesCelsius:F1}°C Humidity {relativeHumidity.Value:F0}% BatteryCharge {batteryCharge:F1}");
// Assemble the JSON payload, should use nanoFramework.Json
string payload = $"{{\"RelativeHumidity\":{relativeHumidity.Value:F0},\"Temperature\":{temperature.DegreesCelsius.ToString("F1")}, \"BatteryCharge\":{batteryCharge:F1}}}";
// Configure the HttpClient uri, certificate, and authorization
string uri = $"{Config.AzureIoTHubHostName}.azure-devices.net/devices/{Config.DeviceID}";
HttpClient httpClient = new HttpClient()
{
SslProtocols = System.Net.Security.SslProtocols.Tls12,
HttpsAuthentCert = new X509Certificate(Config.DigiCertBaltimoreCyberTrustRoot),
BaseAddress = new Uri($"https://{uri}/messages/events?api-version=2020-03-13"),
};
httpClient.DefaultRequestHeaders.Add("Authorization", SasTokenGenerate(uri, Config.Key, DateTime.UtcNow.Add(Config.SasTokenRenewFor)));
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Azure IoT Hub device {Config.DeviceID} telemetry update start");
HttpResponseMessage response = httpClient.Post("", new StringContent(payload));
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Response code:{response.StatusCode}");
response.EnsureSuccessStatusCode();
}
catch (Exception ex)
{
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Azure IoT Hub telemetry update failed:{ex.Message} {ex?.InnerException?.Message}");
Sleep.EnableWakeupByTimer(Config.FailureRetryInterval);
Sleep.StartDeepSleep();
}
Sleep.EnableWakeupByTimer(Config.TelemetryUploadInterval);
#if SLEEP_LIGHT
Sleep.StartLightSleep();
#endif
#if SLEEP_DEEP
Sleep.StartDeepSleep();
#endif
}
The LightSleep or DeepSleep based code is significantly less complex because the allocation and deallocation of resources does not have to be managed because the application is restarted when the WakeUp Timer triggers.
The RAK19007 WisBlock Base Board has a voltage divider (R3&R4 with output ADC_VBAT) which is connected (via R7) to pin 21(AIN0) on the CPU slot connector.
public class Program
{
private const int I2cDeviceBusID = 1;
private const int AdcControllerChannel = 0;
public static void Main()
{
DateTime sasTokenValidUntilUtc = DateTime.UtcNow;
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} devMobile.IoT.RAK.Wisblock.AzureIoTHub.RAK11200.PowerBaseline starting");
Configuration.SetPinFunction(Gpio.IO04, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.I2C1_CLOCK);
if (!WifiNetworkHelper.ConnectDhcp(Config.Ssid, Config.Password, requiresDateTime: true))
{
if (NetworkHelper.HelperException != null)
{
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} WifiNetworkHelper.ConnectDhcp failed {NetworkHelper.HelperException}");
}
Thread.Sleep(Timeout.Infinite);
}
string uri = $"{Config.AzureIoTHubHostName}.azure-devices.net/devices/{Config.DeviceID}";
// not setting Authorization here as it will change as SAS Token refreshed
HttpClient httpClient = new HttpClient
{
SslProtocols = System.Net.Security.SslProtocols.Tls12,
HttpsAuthentCert = new X509Certificate(Config.DigiCertBaltimoreCyberTrustRoot),
BaseAddress = new Uri($"https://{uri}/messages/events?api-version=2020-03-13"),
};
I2cConnectionSettings settings = new(I2cDeviceBusID, Shtc3.DefaultI2cAddress);
I2cDevice device = I2cDevice.Create(settings);
Shtc3 shtc3 = new(device);
AdcController adcController = new AdcController();
AdcChannel batteryChargeAdcChannel = adcController.OpenChannel(AdcControllerChannel);
string sasToken = "";
while (true)
{
DateTime standardisedUtcNow = DateTime.UtcNow;
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Azure IoT Hub device {Config.DeviceID} telemetry update start");
if (sasTokenValidUntilUtc <= standardisedUtcNow)
{
sasTokenValidUntilUtc = standardisedUtcNow.Add(Config.SasTokenRenewEvery);
sasToken = SasTokenGenerate(uri, Config.Key, sasTokenValidUntilUtc);
Debug.WriteLine($" Renewing SAS token for {Config.SasTokenRenewFor} valid until {sasTokenValidUntilUtc:HH:mm:ss dd-MM-yy}");
}
if (!shtc3.TryGetTemperatureAndHumidity(out var temperature, out var relativeHumidity))
{
Debug.WriteLine($" Temperature and Humidity read failed");
continue;
}
double batteryCharge = batteryChargeAdcChannel.ReadRatio() * 100.0;
Debug.WriteLine($" Temperature {temperature.DegreesCelsius:F1}°C Humidity {relativeHumidity.Value:F0}% BatteryCharge {batteryCharge:F1}%");
string payload = $"{{\"RelativeHumidity\":{relativeHumidity.Value:F0},\"Temperature\":{temperature.DegreesCelsius.ToString("F1")}, \"BatteryCharge\":{batteryCharge:F1}}}";
try
{
using (HttpContent content = new StringContent(payload))
{
content.Headers.Add("Authorization", sasToken);
using (HttpResponseMessage response = httpClient.Post("", content))
{
Console.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Response code:{response.StatusCode}");
response.EnsureSuccessStatusCode();
}
}
}
catch (Exception ex)
{
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Azure IoT Hub POST failed:{ex.Message} {ex?.InnerException?.Message}");
}
Debug.WriteLine($"{DateTime.UtcNow:HH:mm:ss} Azure IoT Hub telemetry update done");
Thread.Sleep(Config.TelemetryUploadInterval);
}
}
...
}
I used Azure IoT Explorer to monitor the Azure IoT Hub device telemetry to see how BatteryCharge value decreased to a level where the device wouldn’t transmit.
With no use of the “power conservation” functionality of the ESP32-WROVER-B powered by a 1200mAH battery the device ran for approximately 11hrs (11:00am – 10:00pm).
I think the RAK2305 will not be able to measure “battery charge” as the SENSOR_VP pin on the Espressif ESP32-WROVER-B is not connected to AIN0.
public class Config
{
public const string DeviceID = "RAK11200-RAK19001";
public const string SasSignature = "..."; // sig
public const string SasExpiryTime = "..."; // se
public const string AzureIoTHubHostName = "..";
public const string Ssid = "...";
public const string Password = "..";
...
}
_httpClient = new HttpClient
{
SslProtocols = System.Net.Security.SslProtocols.Tls12,
HttpsAuthentCert = new X509Certificate(Config.DigiCertBaltimoreCyberTrustRoot),
BaseAddress = new Uri($"https://{Config.AzureIoTHubHostName}.azure-devices.net/devices/{Config.DeviceID}/messages/events?api-version=2020-03-13"),
};
string sasKey = $"SharedAccessSignature sr={Config.AzureIoTHubHostName}.azure-devices.net%2Fdevices%2F{Config.DeviceID}&sig={Config.SasSignature}&se={Config.SasExpiryTime}";
_httpClient.DefaultRequestHeaders.Add("Authorization", sasKey);
I then used Visual Studio 2022 Debugger to “single step” further into the BME680 code and the first thing that looked a bit odd was the TryReadTemperatureCore, TryReadPressureCore, TryReadHumidityCore and TryReadGasResistanceCore return values were ignored.
I then single stepped into the TryReadTemperatureCore which was returning a boolean indicating whether the read was success.
private bool TryReadTemperatureCore(out Temperature temperature)
{
if (TemperatureSampling == Sampling.Skipped)
{
temperature = default;
return false;
}
var temp = (int)Read24BitsFromRegister((byte)Bme680Register.TEMPDATA, Endianness.BigEndian);
temperature = CompensateTemperature(temp >> 4);
return true;
}
This library was based on the dotnet/iotBmxx80 code, it looked similar, but I missed an important detail lots more ?’s…
Console.WriteLine("Hello BME680!");
// The I2C bus ID on the Raspberry Pi 3.
const int busId = 1;
// set this to the current sea level pressure in the area for correct altitude readings
Pressure defaultSeaLevelPressure = WeatherHelper.MeanSeaLevel;
I2cConnectionSettings i2cSettings = new(busId, Bme680.DefaultI2cAddress);
I2cDevice i2cDevice = I2cDevice.Create(i2cSettings);
using Bme680 bme680 = new Bme680(i2cDevice, Temperature.FromDegreesCelsius(20.0));
while (true)
{
// reset will change settings back to default
bme680.Reset();
// 10 consecutive measurement with default settings
for (var i = 0; i < 10; i++)
{
// Perform a synchronous measurement
var readResult = bme680.Read();
// Print out the measured data
Console.WriteLine($"Gas resistance: {readResult.GasResistance?.Ohms:0.##}Ohm");
Console.WriteLine($"Temperature: {readResult.Temperature?.DegreesCelsius:0.#}\u00B0C");
Console.WriteLine($"Pressure: {readResult.Pressure?.Hectopascals:0.##}hPa");
Console.WriteLine($"Relative humidity: {readResult.Humidity?.Percent:0.#}%");
if (readResult.Temperature.HasValue && readResult.Pressure.HasValue)
{
var altValue = WeatherHelper.CalculateAltitude(readResult.Pressure.Value, defaultSeaLevelPressure, readResult.Temperature.Value);
Console.WriteLine($"Altitude: {altValue.Meters:0.##}m");
}
if (readResult.Temperature.HasValue && readResult.Humidity.HasValue)
{
// WeatherHelper supports more calculations, such as saturated vapor pressure, actual vapor pressure and absolute humidity.
Console.WriteLine($"Heat index: {WeatherHelper.CalculateHeatIndex(readResult.Temperature.Value, readResult.Humidity.Value).DegreesCelsius:0.#}\u00B0C");
Console.WriteLine($"Dew point: {WeatherHelper.CalculateDewPoint(readResult.Temperature.Value, readResult.Humidity.Value).DegreesCelsius:0.#}\u00B0C");
}
// when measuring the gas resistance on each cycle it is important to wait a certain interval
// because a heating plate is activated which will heat up the sensor without sleep, this can
// falsify all readings coming from the sensor
Thread.Sleep(1000);
}
...
}
The Bme680 Read() method checked the TryReadTemperatureCore, TryReadPressureCore, TryReadHumidityCore & TryReadGasResistanceCore return values.
/// <summary>
/// Performs a synchronous reading.
/// </summary>
/// <returns><see cref="Bme680ReadResult"/></returns>
public Bme680ReadResult Read()
{
SetPowerMode(Bme680PowerMode.Forced);
Thread.Sleep((int)GetMeasurementDuration(HeaterProfile).Milliseconds);
var tempSuccess = TryReadTemperatureCore(out var temperature);
var pressSuccess = TryReadPressureCore(out var pressure, skipTempFineRead: true);
var humiditySuccess = TryReadHumidityCore(out var humidity, skipTempFineRead: true);
var gasSuccess = TryReadGasResistanceCore(out var gasResistance);
return new Bme680ReadResult(tempSuccess ? temperature : null, pressSuccess ? pressure : null, humiditySuccess ? humidity : null, gasSuccess ? gasResistance : null);
}
When I connected to the device with Tera Term it confirmed that the device was in a “kernel panic” loop.
Before I could debug the BME680 sample I had to get the Bmxx80 & Bmxx80.sample projects to compile (update NuGet packages and remove NerdBank.GitVersioning references).
/// <summary>
/// Sets the power mode to the given mode
/// </summary>
/// <param name="powerMode">The <see cref="Bme680PowerMode"/> to set.</param>
/// <exception cref="ArgumentOutOfRangeException">Thrown when the power mode does not match a defined mode in <see cref="Bme680PowerMode"/>.</exception>
[Property("PowerMode")]
public void SetPowerMode(Bme680PowerMode powerMode)
{
//if (!powerMode.Equals(Bme680PowerMode.Forced) &&
// !powerMode.Equals(Bme680PowerMode.Sleep))
//{
// throw new ArgumentOutOfRangeException();
//}
var status = Read8BitsFromRegister((byte)Bme680Register.CTRL_MEAS);
status = (byte)((status & (byte)~Bme680Mask.PWR_MODE) | (byte)powerMode);
SpanByte command = new[]
{
(byte)Bme680Register.CTRL_MEAS, status
};
_i2cDevice.Write(command);
}
The first problem was the two powerMode.Equals statements used to validate the powerMode parameter around line 287 in Bme680.cs so I commented them out.
On start-up references to readResult.GasResistance.Ohms would regularly fail, so I commented out everywhere it was used.
Then references to readResult.Pressure.Hectopascals would randomly fail, so I commented out everywhere it was used.
public static void RunSample()
{
Debug.WriteLine("Hello BME680!");
//////////////////////////////////////////////////////////////////////
Configuration.SetPinFunction(Gpio.IO04, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.I2C1_CLOCK);
// The I2C bus ID on the MCU.
const int busId = 1;
// set this to the current sea level pressure in the area for correct altitude readings
Pressure defaultSeaLevelPressure = WeatherHelper.MeanSeaLevel;
I2cConnectionSettings i2cSettings = new(busId, Bme680.DefaultI2cAddress);
I2cDevice i2cDevice = I2cDevice.Create(i2cSettings);
using Bme680 bme680 = new Bme680(i2cDevice, Temperature.FromDegreesCelsius(20.0));
while (true)
{
// reset will change settings back to default
bme680.Reset();
// 10 consecutive measurement with default settings
for (var i = 0; i < 10; i++)
{
// Perform a synchronous measurement
var readResult = bme680.Read();
// Print out the measured data
//Debug.WriteLine($"Gas resistance: {readResult.GasResistance.Ohms}Ohm");
Debug.WriteLine($"Temperature: {readResult.Temperature.DegreesCelsius}\u00B0C");
//Debug.WriteLine($"Pressure: {readResult.Pressure.Hectopascals}hPa");
Debug.WriteLine($"Relative humidity: {readResult.Humidity.Percent}%");
/*
if (!readResult.Temperature.Equals(null) && !readResult.Pressure.Equals(null))
{
var altValue = WeatherHelper.CalculateAltitude(readResult.Pressure, defaultSeaLevelPressure, readResult.Temperature);
Debug.WriteLine($"Altitude: {altValue.Meters}m");
}
if (!readResult.Temperature.Equals(null) && !readResult.Humidity.Equals(null))
{
// WeatherHelper supports more calculations, such as saturated vapor pressure, actual vapor pressure and absolute humidity.
Debug.WriteLine($"Heat index: {WeatherHelper.CalculateHeatIndex(readResult.Temperature, readResult. Humidity).DegreesCelsius}\u00B0C");
Debug.WriteLine($"Dew point: {WeatherHelper.CalculateDewPoint(readResult.Temperature, readResult.Humidity).DegreesCelsius}\u00B0C");
}
*/
// when measuring the gas resistance on each cycle it is important to wait a certain interval
// because a heating plate is activated which will heat up the sensor without sleep, this can
// falsify all readings coming from the sensor
Thread.Sleep(1000);
}
...
}
The RAK2305 WisBlock Wifi Interface Module has the TX0 pin is connected to pin 11, RX0 is connected to pin 12, TX1 pin (Gpio.IO21) is connected to pin 34, and the RX1 pin (Gpio.IO21) is connected to pin 33 of the IO Slot connector (crossover TX & RX).
The RAK4630 Module is plugged into the CPU slot (BTB40_F) of the RAK5005 Base Board with TX pin 33 and RX pin 34. The RAK4630 Module UART2_TX pin is connected to 33, and the UART2_RX is connected to 34 on the CPU slot.
I then read the RAK4630 AT Command documentation to see if I could enable AT Commands on the second serial port
I had a look at the RAK4360 RAK Unified Interface (RUI) code to see if I could modify it so UART1 responded to AT Commands but I’m not certain this would work.
This is a longish post about failure, it took many hours to explore all the different approaches which was way longer than I should have spent. For why see “sunk cost fallacy”
I was using Azure IoT Explorer to monitor the telemetry and found that the initial versions of the application would fail after 6 or 7 hours. After reviewing the code I added a couple of “using” statements which appear to have fixed the problem as the soak test has been running for 12hrs, 24hrs, 36hrs, 48hrs, 96hrs…