about allsky heater+ pcb

[OE8HSR]

hello ladies and gentleman.

my name is hans from austria.

i have found the indi allsky project by watching the allsky video of dylan o donnel and i really like your software at first glance.

in my spare time i design printed circuit boards and im currently working on a heater + sensor pcb for an allsky camera.

the pcb features:
a 5 w dewheater powered via 12v and controlled via pwm.
another auxilary 12v pwm output for controlling other things like a fan.
a bosch sensor for meassuring temperature, humidity and air pressure
a sensor to detect lightning
a sensor to detect light brightness
a sensor to meassure the light spectrum
a sensor to meassure voltace, current and power (for the 12v heater, auxilary rail)

i received the first prototype batch of the pcb and im currently testing the hardware.

i hope to get this done soon so i can write the code for the pcb.

it would be great if you could take a look at it and let me know if this is interesting for the community and if it would be interesting to integrate the hardware into your allsky code.

best wishes from austria
hans

[aaronwmorris]

This is really cool! What kind of sensors are you planning on implementing for each of the functions?

[OE8HSR]

hello aaron.
thank you for the reply.

on the pcb i have implemented:
PWM controlled Heatingresistors
PWM controlled AUX Connector (12V)
750mA Polyfuse protection

INA226 Currentsensor
TCS3448 Lightspectrumsensor
TSL2591 Lightsensor
AS3935 Lightningsensor
BME280 Temp/Humidity/Airpressure-sensor

im currently working on the testcode and it works quite well. i have to debug the auxilary pwm port and an issue with the lightning sensor.

surprisingly my design worked out of the box :)

i have designed the pcb for the housing from "daniel nimmervoll" (https://www.liquidart-shop.at/de/allsky-kamera-gehaeuse-armor.html)
but its very small design should also work in other housings.

im currently only testing but it looks promising. =)

best wishes from austria
hans

[OE8HSR]

hello aaron.
may i ask from what country you are from?
im still testing if the hardware works and i have some bug to fix but when it works id be happy to send you a pcb for testing and maybe implementing it into your software. but it depends what the regulations for your country is with shipping homemade electronic components...

maybe you have other ideas or recommendations on what to implement in a next version.=)
may i also ask if you are familiar to soldering because a few parts need handsoldering.

best wishes
hans

[aaronwmorris]

I think I would be interested in doing that. Soldering does not bother me, I am quite fond of it. :-)

indi-allsky already supports the following sensors:

• TSL2591 Lux
• AS3935 Lightning
• BME280 Temp

The following sensors would need to be added:

• INA226 Current
• TCS3448 Spectrum

The challenge with adding sensors is they would need to to utilize the Adafruit Circuit Python interface for I2C. The typical SMBUS interface in python does not allow multiple modules to access the same I2C bus concurrently. If you manage all of the sensors in the same module it works fine, but indi-allsky interfaces each sensor in a separate module. Circuit Python implements an I2C singleton to permit concurrent access.

[OE8HSR]

hello aaron.

i have noticed that indiallsky supports the sensors. but i have not tested it yet. currently im running a script that reads the sensors, controlls the dewheater and sends the sensor values to a database. (for visualisation with grafana.)

there is an ina226 library available an i (i as in AI XD) made a small python library for the tcs3448 sensor.

most of the hardware works fine. i still have to debug the lightning sensor. there is something fishy. it gets noticed over i2c but it isnt working yet. i hope its just a software, pin issue...

best wishes
hans

[aaronwmorris]

I was not very successful in using either of my (I have 2) AS3935 sensors using I2C. I have only been successful in using it in SPI mode.

In fact, most manufacturers that sold the AS3935 stopped supporting the sensor in I2C mode. It is not very clear, but there was some problem with the I2C implementation that was non-standard. SPI mode is recommended.

[OE8HSR]

hey aaron.

thank you for the hint! i didnt know that there was an issue with i2c. i will take a look at that.
in my case the sensor is hardwired to i2c on the pcb. i will check how i could implement the spi communication.

currently im routing 12 cables to the raspberry pi and if i want to use spi, i have to route 2 more...

maybe it would be the best idea to ad a microcontroller to the board that reads out the sensors and then the microcontroller communicates directly with the raspberry pi. ill think about this a bit...

best wishes
hans