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Aaron W Morris edited this page Jan 30, 2026 · 95 revisions

Overview

indi-allsky supports reading external sensors (eg temperature) with SBCs like Raspberry Pi.

Unsupported Hardware

If you have an unsupported sensor, please open an Enhancement Issue and I will investigate adding support. It may take a week or two if I have to order the part.

GPIO Permissions

If you receive a PermissionDenied exception when accessing GPIO pins

https://github.com/aaronwmorris/indi-allsky/wiki/GPIO-Permissions

Raspberry Pi 5 - RuntimeError: Cannot determine SOC peripheral base address

source virtualenv/indi-allsky/bin/activate

pip uninstall RPi.GPIO rpi.lgpio

pip install --upgrade rpi.lgpio

Sensor Units

Sensor values may be reported in either Celcius or Fahrenheit depending on the setting for Temperature Display on the Camera tab under configuration.

Slots/Probes

Data is shared between the indi-allsky processes using a multiprocessing Array. Each sensor module supports a different number of sensor probes. Some sensors only support a single probe, others support multiple eg temperature, humidity, pressure, etc. The code will populate multiple slots of data based on each sensor probe.

All data from probes are floating point values.

System Temperature Slots

There are 60 (0-59) slots for system temperatures.

  • 0 is the camera temperature
  • 1-9 are reserved for future use
  • Slots 10-59 are for all sensor values returned by psutil.sensors_temperatures(). Raspberry Pi 1-4 will have a single sensor value (CPU temp), Pi5 has 2 temperatures (CPU Temp, GPU Temp). Generic PCs can have many temperatures returned. The order of the temperature values is not controllable, the first is NOT always the CPU temperature. The order and label for the temperatures can be seen on the System page.

System Temp Slot Overlay variables

{sensor_temp_1:0.1f}
{sensor_temp_2:0.1f}
{sensor_temp_3:0.1f}
{sensor_temp_4:0.1f}
{sensor_temp_5:0.1f}
{sensor_temp_6:0.1f}
{sensor_temp_7:0.1f}
{sensor_temp_8:0.1f}
{sensor_temp_9:0.1f}
{sensor_temp_10:0.1f}
...
{sensor_temp_59:0.1f}

User Slots

There are 60 (0-59) sensor slots for user data.

  • 0 is the camera temperature
  • 1 is the dew heater state (duty cycle)
  • 2 is the dew point temperature
  • 3 is the frost point temperature
  • 4 is the fan state (duty cycle)
  • 5 is the heat index
  • 6 is the wind direction in degrees
  • 7 is sqm
  • 8-9 are reserved for future use
  • Slots 10-59 are available to be assigned for sensors.

User Slot Overlay variables

{sensor_user_1:0.1f}
{sensor_user_2:0.1f}
{sensor_user_3:0.1f}
{sensor_user_4:0.1f}
{sensor_user_5:0.1f}
{sensor_user_6:0.1f}
{sensor_user_7:0.1f}
{sensor_user_8:0.1f}
{sensor_user_9:0.1f}
{sensor_user_10:0.1f}
...
{sensor_user_59:0.1f}

Chart Titles

Chart titles may be customized by updating the title template

Default: {name:s} - {label:s} - {probe:s}

Title Variables

Name Type Info
name str Sensor Name
title str Sensor Title
probe str Probe Name

Testing sensors

There is a test script will will execute the same code that indi-allsky utilizes so you do not have to start the program to validate their behavior.

source virtualenv/indi-allsky/bin/activate

./misc/sensor_test.py

Interfaces

I2C

The I2C interface may be activated with sudo raspi-config on Raspberry Pi systems. sudo armbian-config on Armbian.

Use i2cdetect -y 1 to inspect the I2C bus to find the correct address for your device.

i2c extended detection

Use the following command to scan the lower 7 addresses. i2cdetect -a -y 1 0x00 0x77

sudo apt-get install i2c-tools

Alternate I2C buses

On a Raspberry Pi, most people would use I2C bus 1 (pins 2/3). However, there are cases where it is necessary to use I2C bus 0 (pins 27/28) if a HAT is using those pins. The code will have to be manually updated to use the alternate bus.

  • /etc/firmware/config.txt

      dtparam=i2c_vc=on

  • Sensor modifications

         i2c_address_str = kwargs['i2c_address']
 
         import board
-        #import busio
+        import busio
         import adafruit_bh1750
 
         i2c_address = int(i2c_address_str, 16)  # string in config
 
         logger.warning('Initializing [%s] BH1750 I2C light sensor device @ %s', self.name, hex(i2c_address))
-        i2c = board.I2C()
+        #i2c = board.I2C()
+        i2c = busio.I2C(board.D1, board.D0, frequency=100000)  # Raspberry Pi i2c bus 0 (pins 28/27)
         self.bh1750 = adafruit_bh1750.BH1750(i2c, address=i2c_address)

SPI

The SPI interface may be activated with sudo raspi-config on Raspberry Pi systems.

1-Wire

The 1-Wire interface may be activated with sudo raspi-config on Raspberry Pi systems.

The default 1-Wire pin on Raspberry Pi devices is GPIO4 (pin 7). This can be overridden in /boot/firmware/config.txt

dtoverlay=w1-gpio,gpiopin=5

Note: The pin designated as 1-Wire cannot be used as a GPIO pin while this overlay is active.

Sensors

Sensor Type Status
OpenWeather Map API Temp Working
Weather Underground API Temp Working
Astrospheric API Temp Working
Ambient Weather API Temp Working
Ecowitt API Temp Working
MQTT Broker Working
DS18x20 Temp Working
DHT11 Temp Working
DHT21 Temp My sample did not work
DHT22 Temp Working
SHT20 Temp Select HTU21D interface
SHT3x Temp Working - Heater untested
SHT4x Temp Working - Heater untested
HTU21D Temp Working
HTU31D Temp Not tested - Heater untested
AHT10/20 Temp Working
BMP180 Temp Working
BMP280 Temp Working - BMP do not report humidity
BME280 Temp Working
BME680 Temp Working
BMP3xx Temp Untested
Si7021 Temp Working - Heater untested
SCD-30 Temp Untested
SCD-4x Temp Untested
HDC302x Temp Untested
MLX90614 Sky Temp Working
MLX90615 Sky Temp Working
MLX90640 Thermal Camera Working
TMP36 via ADS1015 Temp Working
TMP36 via ADS1115 Temp Untested
LM35 via ADS1015 Temp Untested
LM35 via ADS1115 Temp Untested
TSL2561 Light Working
TSL2591 Light Working
VEML7700 Light Working
BH1750 Light Working
SI1145 Light Working
LTR390 Light Working
MMC5983MA Magnet Working
INA219 Current Working
INA228 Current Working
INA23x Current Untested
INA260 Current Untested
INA3221 Current Untested
AS3935 Lightning Working (beta)

OpenWeather Map

The OpenWeather Map API may be used to query local weather conditions for your location. This is not a physical sensor, but data is returned for your local weather conditions based on longitude and latitude.

https://openweathermap.org/api

The API is queried every 5 minutes, therefore there should be no more than 288 (automated) queries per day.

Returns 10 values:

  • temperature
  • "Feels Like" temperature
  • humidity
  • pressure
  • clouds percent
  • wind speed
  • wind gusts
  • 1h rain
  • 1h snow
  • dew point

Additional values:

  • dew point
  • frost point
  • heat index
  • wind direction

Weather Underground

The Weather Underground API may be used to query weather conditions. This is not a physical sensor, but data is returned for your local weather conditions based on a given Station ID.

https://www.wunderground.com/

The API is queried every 5 minutes, therefore there should be no more than 288 (automated) queries per day.

Note: The Pin/Port field is used for the Station ID

Returns 9 values:

  • temperature
  • humidity
  • pressure
  • wind speed
  • wind gusts
  • total rain
  • solar radiation
  • uv
  • dew point

Additional values:

  • dew point
  • frost point
  • heat index
  • wind direction

Astrospheric

The Astrospheric API may be used to query weather conditions. This is not a physical sensor, but data is returned for your local weather conditions based on a given Latitude/Longitude.

https://www.astrospheric.com/

The API is queried every 120 minutes, therefore there should be no more than 12 (automated) queries per day.

Note: As of January 2025, users are granted 100 API credits per day and each call to the API incurs a cost of 5 credits.

Returns 6 values:

  • temperature
  • atmospheric seeing
  • atmospheric transparency
  • clouds percent
  • wind speed
  • dew point

Additional values:

  • dew point
  • frost point
  • wind direction

Ambient Weather

The Ambient Weather API may be used to query weather conditions provided by your local weather device. This is not a physical sensor, but data is returned for your local weather conditions provided by your Ambient Weather internet connected device.

https://www.ambientweather.net/

API Key Instruction: https://ambientweather.com/faqs/question/view/id/1834/

The API is queried every 5 minutes.

Returns 10 values:

  • temperature
  • feels like seeing
  • relative humidity
  • atmospheric pressure
  • wind speed
  • wind gust speed
  • 1hr rain
  • solar radiation
  • uv
  • dew point

Additional values:

  • dew point
  • frost point
  • heat index
  • wind direction

Ambient Weather requires three values to access their API:

  • API Key - Obtained from your ambientweather.net Dashboard, Account, then API Keys. Create a new API Key or re-use an existing one.
  • Application Key - Obtained from the same page as the API Key. Create an Application key by clicking the Developers Click here link. You're asked to describe the application that you are developing. Indicate that you'll be using the API to get data for a personal All Sky camera.
  • Device MAC Address - Obtained from the Devices page.

NOTE: Not all values will populate with data. Values will only be populated for the data sent by your weather station.

Ecowitt

The Ecowitt API may be used to query weather conditions provided by your local weather device. This is not a physical sensor, but data is returned for your local weather conditions provided by your Ecowitt internet connected device.

https://www.ecowitt.net/

The API is queried every 5 minutes.

Returns 10 values:

  • temperature
  • feels like seeing
  • relative humidity
  • atmospheric pressure
  • wind speed
  • wind gust speed
  • 1hr rain
  • solar radiation
  • uv
  • dew point

Additional values:

  • dew point
  • frost point
  • heat index
  • wind direction

Ecowitt requires three values to access their API:

  • API Key - Obtained from your ecowitt.net Dashboard. Click your account icon then User Profile Create a new API Key or re-use an existing one.
  • Application Key - Obtained from the same page as the API Key. You're asked to describe the application that you are developing. Indicate that you'll be using the API to get data for a personal All Sky camera.
  • Device MAC Address - Obtained from the Devices page (unconfirmed).

MQTT Broker Sensor

A sensor value from an MQTT Broker may be queried. The Pin field is used for the topic subscription. Up to 10 topics may be subscribed by providing a comma separated list. eg topic1,base/topic2

The payload for the topics must be a value that can be converted to a float.

The Labels for the MQTT, Topic 1, Topic 2, etc, are statically defined within the sensor code. If you want to alter these names, the METADATA code will have to be changed. https://github.com/aaronwmorris/indi-allsky/blob/main/indi_allsky/devices/sensors/mqttBrokerSensor.py

Returns 10 float values

DS18x20 Dallas Temperature Sensor

This sensor is a 1-Wire interface type device. On Raspberry Pi, the default 1-Wire pin is GPIO4 (pin 7). The Pin in the indi-allsky config is not used.

Returns 1 value:

  • temperature

DHT11/21/22 Temperature Sensor

This sensor only requires a single pin and in some cases a pull up resistor.

Returns 3 values:

  • temperature
  • humidity
  • dew point

BMP180 Temperature Sensor

The BMP180 has an i2c interface. Common I2C addresses are 0x77 and 0x76.

Returns 2 values:

  • temperature
  • pressure
Pin I2C Note
VCC 5v on 5 pin sensors, 3.3v on 4 pin modules
GND
SLC SLC Raspi pin 5 (GPIO 3)
SDA SDA Raspi pin 3 (GPIO 2)
3.3 Not available on 4 pin modules

BMP280 Temperature Sensor

The BME280 can be used in either i2c or SPI modes. Common I2C addresses are 0x77 and 0x76.

BMP280 does not support humidity measurements. Without the humidity measurement, dew point calculations will not be available.

Returns 2 values:

  • temperature
  • pressure
Pin I2C SPI Note
VCC Usually 3.3v
GND
SLC SLC SCLK I2C - Raspi pin 5 (GPIO 3)
SPI - Raspi pin 23 (SCLK) (GPIO 11)
SDA SDA MISO I2C - Raspi pin 3 (GPIO 2)
SPI - Raspi pin 19 (MOSI) (GPIO 10)
CSB CS SPI - Any GPIO pin
SDO MOSI SPI - Raspi pin 21 (MISO) (GPIO 9)

BME280 Temperature Sensor

The BME280 can be used in either i2c or SPI modes. Common I2C addresses are 0x77 and 0x76.

Returns 4 values:

  • temperature
  • humidity
  • pressure
  • dew point
Pin I2C SPI Note
VCC Usually 3.3v
GND
SLC SLC SCLK I2C - Raspi pin 5 (GPIO 3)
SPI - Raspi pin 23 (SCLK) (GPIO 11)
SDA SDA MISO I2C - Raspi pin 3 (GPIO 2)
SPI - Raspi pin 19 (MOSI) (GPIO 10)
CSB CS SPI - Any GPIO pin
SDO MOSI SPI - Raspi pin 21 (MISO) (GPIO 9)

Chip ID 0x58

RuntimeError: Failed to find BME280! Chip ID 0x58

If you receive this Exception, you have a BMP280 module (not BME). You should use the separate BMP280 support, but if you need to use the BME280 module, edit virtualenv/indi-allsky/lib/python3.##/site-packages/adafruit_bme280/basic.py and set _BME280_CHIPID to 0x58

BME680 Temperature Sensor

The BME680 can be used in either i2c or SPI modes. Common I2C addresses are 0x77 and 0x76.

Returns 5 values:

  • temperature
  • humidity
  • pressure
  • gas (ohm)
  • dew point
Pin I2C SPI Note
VCC Usually 3.3v
GND
SLC SLC SCLK I2C - Raspi pin 5 (GPIO 3)
SPI - Raspi pin 23 (SCLK) (GPIO 11)
SDA SDA MISO I2C - Raspi pin 3 (GPIO 2)
SPI - Raspi pin 19 (MOSI) (GPIO 10)
SDO MOSI SPI - Raspi pin 21 (MISO) (GPIO 9)
CSB CS SPI - Any GPIO pin

BME680 notes

  • The initial humidity measurement may always be 100%. Subsequent measurements should be correct.

BMP3xx Temperature Sensor

The BMP3xx can be used in either i2c or SPI modes. Default I2C addresses is 0x77.

Returns 3 values:

  • temperature
  • humidity
  • dew point

Si7021 Temperature Sensor

The Si7021 has an i2c interface. Default I2C address is 0x40.

An internal heater is available for high humidity environments.

Returns 3 values

  • temperature
  • humidity
  • dew point

SHT3x Temperature Sensor

The SHT3x has an i2c interface. Common I2C addresses are 0x44 and 0x45.

An internal heater is available for high humidity environments.

Returns 3 values

  • temperature
  • humidity
  • dew point

SHT40/41/45 Temperature Sensor

The SHT4x has an i2c interface. Common I2C addresses are 0x44 and 0x45.

An internal heater is available for high humidity environments.

Returns 3 values

  • temperature
  • humidity
  • dew point

HTU21D Temperature Sensor

The HTU21D has an i2c interface. Default I2C address is 0x40.

Returns 3 values

  • temperature
  • humidity
  • dew point

HTU31D Temperature Sensor

The HTU31D has an i2c interface. Common I2C addresses are 0x40 and 0x41.

An internal heater is available for high humidity environments.

Returns 3 values

  • temperature
  • humidity
  • dew point

AHT10/20 Temperature Sensor

The AHTx0 has an i2c interface. Default I2C address is 0x38.

Returns 3 values

  • temperature
  • humidity
  • dew point

SCD-30 Temperature Sensor

The SCD30 has an i2c interface. Default I2C address is 0x61.

Returns 4 values

  • temperature
  • humidity
  • CO2
  • dew point

SCD-4x Temperature Sensor

The SCD40 and SCD41 has an i2c interface. Default I2C address is 0x62.

Returns 4 values

  • temperature
  • humidity
  • CO2
  • dew point

AHT10/20 Temperature Sensor

The AHTx0 has an i2c interface. Default I2C address is 0x38.

Returns 3 values

  • temperature
  • humidity
  • dew point

HDC302x Temperature Sensor

The HDC302x has an i2c interface. Common I2C addresses are 0x44, 0x45, 0x46, and 0x47.

Returns 2 values:

  • temperature
  • pressure

TMP36 Temperature Sensor via ADS1x15 ADC

The ADS1x15 ADC has an i2c interface. Common I2C addresses are 0x48, 0x49, 0x4a, and 0x4b

The ADC reads the analog voltage from the TMP36 sensor which is converted to the temperature value.

Returns 1 value

  • temperature

LM35 Temperature Sensor via ADS1x15 ADC

The ADS1x15 ADC has an i2c interface. Common I2C addresses are 0x48, 0x49, 0x4a, and 0x4b

The ADC reads the analog voltage from the LM35 sensor which is converted to the temperature value.

Returns 1 value

  • temperature

MLX90614 Sky Temperature

This MLX90614 has an i2c interface. Default i2c address is 0x5a

Note: My module was not detected with i2cdetect, but it still worked.

Returns 2 values:

  • temperature
  • sky_temperature

MLX90615 Sky Temperature

This MLX90615 has an i2c interface. Default i2c address is 0x5b

Returns 2 values:

  • temperature
  • sky_temperature

MLX90640 Thermal Camera

This MLX90640 has an i2c interface. Default i2c address is 0x33

Thermal image is TBD.

Returns 1 value:

  • avg_temperature

TSL2561 Light Sensor

The TSL2561 has an i2c interface. Default i2c address is 0x39

Returns 3 values:

  • lux
  • broadband
  • infrared

TSL2591 Light Sensor

The TSL2561 has an i2c interface. Default i2c address is 0x29

Returns 4 values:

  • lux
  • visible
  • infrared
  • full_spectrum

VEML7700 Light Sensor

The VEML7700 has an i2c interface. Default i2c address is 0x10

Returns 4 values:

  • lux
  • light
  • white light

BH1750 Light Sensor

The BH1750 has an i2c interface. Default i2c address is 0x23

Returns 1 value:

  • lux

SI1145 UV Light Sensor

The SI1145 has an i2c interface. Default i2c address is 0x60

Returns 3 values:

  • visible
  • ir
  • uv index

LTR390 UV Light Sensor

The LTR390 has an i2c interface. Default i2c address is 0x53

Returns 4 values:

  • uv
  • light
  • uv index
  • lux

MMC5983MA Magnetometer/Gauss Sensor

The MMC5983MA has an i2c interface. Default i2c address is 0x30

Returns 4 values:

  • x gauss
  • y gauss
  • z gauss
  • temperature

INA219 Current Sensor

The INA219 has an i2c interface. Common I2C addresses are 0x40 (default), 0x41, 0x42, and 0x43

Returns 3 values:

  • voltage
  • current
  • watts

INA228 Current Sensor

The INA228 has an i2c interface. Common I2C addresses are 0x40 (default), 0x41, 0x42, and 0x43

Returns 4 values:

  • voltage
  • current
  • watts
  • die temperature

INA23x Current Sensor

The INA237 and INA238 have an i2c interface. Common I2C addresses are 0x40 (default), 0x41, 0x42, and 0x43

Returns 4 values:

  • voltage
  • current
  • watts
  • die temperature

INA260 Current Sensor

The INA260 has an i2c interface. Common I2C addresses are 0x40 (default), 0x41, 0x42, and 0x43

Returns 3 values:

  • voltage
  • current
  • watts

INA3221 Current Sensor

The INA3221 has an i2c interface. Common I2C addresses are 0x40 (default), 0x41, 0x42, and 0x43

Returns 9 values:

  • channel 1 voltage
  • channel 1 current
  • channel 1 watts
  • channel 2 voltage
  • channel 2 current
  • channel 2 watts
  • channel 3 voltage
  • channel 3 current
  • channel 3 watts

AS3935 Lightning Sensor

The AS3935 Lightning sensor has a SPI and i2c interface. Common I2C addresses are 0x03 (default), 0x02, and 0x01

The recommended configuration is the SPI interface. The i2c interface has some documented stability problems.

The AS3935 relies on interrupts to indicate when lightning strikes occur which requires a second GPIO pin. In SPI mode, pin1 is CS, pin2 is INT. In i2c mode, pin1 is not used (set any valid pin) and pin2 is INT. Interrupt code uses RPi.GPIO therefore this will only on a Raspberry Pi.

Use the following command to scan the lower 7 addresses. i2cdetect -a -y 1 0x00 0x77

Testing: An electronic lighter or powering up a fluorescent light (with ballast) can be a decent test to see if the sensor responds. These will usually be detected as noise, not lightning strikes.

Note: The AS3935 module is basically a noise detector. It is designed to detect EMF noise emissions that roughly correspond with what lightning strikes produce. It is very susceptible to other noise.

Returns 4 values:

  • strike count
  • minimum distance
  • maximum distance
  • average distance
  • disturber count
  • noise count
Pin I2C Note
VCC 3.3v
GND
SCL SCL Raspi pin 5 (GPIO 3)
MOSI SDA Raspi pin 3 (GPIO 2)
SI SI Low SPI, High i2c

Test Data Generator

This simulates a sensor with 4 data points. For development systems.

Returns 4 values

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