318 replies to this topic

[mlord]

The HBG3 project has now been updated again, to v6.12, with more Dew Heater protocol fixes etc:  https://www.cloudyni...7#entry12784728

 

At this point, all further development and comment will be done mainly in the main HomeBrew Gen3 (HBG3) thread, so this original Dew Heater thread will likely fall into disuse.  Meanwhile, here's a screenshot of CPWI talking to the HomeBrew Dew Heater over HomeBrew WiFi on the same device:

 

[Splunge!]

Hi Mark,

 

  I finally assembled all the parts to make a standalone version of your dew heater control. I want it to just be a 'black box' that is powered by the 12V dew heater input, no display. One question before I start putting it together... how is the Pro Micro board powered? I don't see in the instructions any mention of attaching anything to the 'RAW' pin. Should the 'VCC' pin of the MOSFET board attach to the 'RAW' pin of the Pro Micro? Or is it powered some other way? Want to know before I start soldering.

 

  Thanks for creating this project!

 

Regards,

Edited by Splunge!, 13 August 2023 - 03:19 PM.

[mlord]

The instructions I gave say to use a buck converter to drop the 12V down to power the Pro Micro.

[mlord]

The instructions I gave say to use a buck converter to drop the 12V down to power the Pro Micro.

Ideally, one would use an adjustable-output style of buck converter.  Feed it with 12V input, ground the GND pin, and set the buck output to about 6.5V.  Feed that output to the Vin/Raw pin of the Pro Micro, which will then downconvert it to 5V for use.

 

If the Buck is instead set for 5V output, then the Pro Micro will end up being under-volted after it's own onboard linear regulator is involved. This will ruin the thermistor readings.

Edited by mlord, 13 August 2023 - 06:52 PM.

[Splunge!]

 OK, thanks - I see that now. Was looking at the wiring instructions in the file you posted where it wasn't mentioned. The Pro Micro instructions say it can take up to 12V at .'RAW', but I'll probably get a converter anyway. Amazon has a small 12V to 7.5V that looks like it will do...

 

Regards,

[mlord]

Most Pro Micro boards go up in smoke at anything higher than 9.5V.

The genuine Sparkfun branded ones usually work at 12V, so long as there's not much current being pulled from the 5V Vcc pin.

One of those will probably work here, so long as the actual input voltage stays at 12V or less. A lot of telescope battery arrangements output higher than that.

Edited by mlord, 14 August 2023 - 06:58 AM.

[Splunge!]

 Good to know, thanks. No idea how much current the thermistor and SHT30 draw - can't be much - but I'll be safe and try to cram in the buck converter. I'll post some pictures when I have it all together, and probably questions about testing it...

 

Regards,

[dlwmacgregor]

Would a 1N4004 diode work just as well?

[mlord]

Should be fine.

[dlwmacgregor]

1/4 watt or 1/2 watt resistors?

[mlord]

Any wattage is fine. There's no current to speak of going through them. 1/16 watt would even be okay.

[mlord]

Any wattage is fine. There's no current to speak of going through them. 1/16 watt would even be okay.

The math for this is easy. Ohms Law says, 3.3V logic through a 10K resistor is (3.3 / 10000) = 0.00033amps. Wattage is voltage times amps, so 3.3 x 0.00033 = about 1/1000 watt. 🙂

[dlwmacgregor]

Thanks.

Been a long time since I've done any of those calculations. 

[Splunge!]

Mark,
 
  Finally got. it all together. I took your advice and went with an adjustable buck converter, set to 6.5V. Attached are some pics.

 

 

 

Plugged it in, the power light came on and no smoke came out... woohoo!

 

 Now for testing. I got the Arduino IDE and loaded your program file and necessary libraries and believe I loaded it into the Pro Micro (this is my first attempt at doing an arduino based project). Now I need to be able to read the sensors to verify if it is working - what software tools do you use for doing that? Any tips for testing (in particular, reading the sensors) would be most appreciated.

 

Regards,

Edited by Splunge!, 19 August 2023 - 01:11 PM.

[mlord]

Easiest way is to open the Arduino Serial Monitor (115200) and watch the output generated there.

And/or hook up an OLED display to the I2C pins of the Arduino.

 

Breath warm moist air onto the ambient sensor, and the Dew controller will eventually turn on the PWM output, warming the heater.

 

My multi-meter has a temperature probe, which I have used on the heater to verify it does warm up.  But the thermistor also does that, and increasing temperature will be shown on the serial/OLED ouputs too.

Edited by mlord, 19 August 2023 - 01:19 PM.

[dlwmacgregor]

Nice neat job on that.

I've got most of the discrete components except the temp/hum sensor and the Celectron Dew Heater (I'll probably get that next month).

 

Mark, are you working on or plan to work on a PCB for the controller?

Your basic circuit diagram for it is confusing me. It only has 2 connections for the thermistor and the one I am going for has 4. (SHT31)

 

https://www.amazon.c..._lig_dp_it&th=1

 

Or maybe I'm reading it wrong.

 

Also, Splunge!  I see you didn't use the V+ and V- connections on the IRF520 like Mark did on his prototype.

Is there a reason for that?

Edited by dlwmacgregor, 19 August 2023 - 02:28 PM.

[mlord]

Mark, are you working on or plan to work on a PCB for the controller?

Your basic circuit diagram for it is confusing me. It only has 2 connections for the thermistor and the one I am going for has 4. (SHT31)

I get confused like that too from time to time.. must be our ages! 

 

The SHT30/SHT31 is the ambient conditions sensor, not the thermistor.    It has a 4-wire connection to the I2C pads on the HBG3.   The thermistors are different beasts, each requiring a 10K resistor to form a voltage divider, the middle point of which feeds into a GPIO pin on the ESP32.

 

EDIT:  I do hope one day to produce a PCB, as there are just SO MANY connections required for this add-on.  But no time for that until perhaps Christmas.

Edited by mlord, 19 August 2023 - 02:24 PM.

[mlord]

  Finally got. it all together. I took your advice and went with an adjustable buck converter, set to 6.5V. Attached are some pics.

I'm not sure that you've wired the IRF520 module correctly.  See this photo here for how to do it, thinking "heater" in place of "laser":
https://xunker.githu...ted resized.JPG

 

EDIT:  still too confusing. Here:

 

V+ and V- connect to the actual dew heater.

VIN & GND come from +12V.

 

SIG comes from the GPIO pin of the Arduino, through a diode.

VCC connects to nothing.

GND here connects to the Arduino GND.

 

Here's my own photo of the wiring:  https://www.cloudyni...-1683750248.jpg

Edited by mlord, 19 August 2023 - 02:32 PM.

[dlwmacgregor]

I get confused like that too from time to time.. must be our ages! 

 

The SHT30/SHT31 is the ambient conditions sensor, not the thermistor.    It has a 4-wire connection to the I2C pads on the HBG3.   The thermistors are different beasts, each requiring a 10K resistor to form a voltage divider, the middle point of which feeds into a GPIO pin on the ESP32.

 

EDIT:  I do hope one day to produce a PCB, as there are just SO MANY connections required for this add-on.  But no time for that until perhaps Christmas.

OK. I see it now.

I also see 2 thermistor pads on the HBGe PCB.

Is that part of your plan to incorporate the Dew Heater Controller into the HBG at some point in the future?

[mlord]

OK. I see it now.

I also see 2 thermistor pads on the HBGe PCB.

Is that part of your plan to incorporate the Dew Heater Controller into the HBG at some point in the future?

So two pads, one for each of two thermistors.

No actual wiring change there, I'm just labelling the pads for the first time. 

 

If I ever do make a Dew Controller PCB, it will be a separate add-on that gets wired to the regular HBG3.
 

[dlwmacgregor]

So two pads, one for each of two thermistors.

No actual wiring change there, I'm just labelling the pads for the first time. 

 

If I ever do make a Dew Controller PCB, it will be a separate add-on that gets wired to the regular HBG3.
 

Is that the reason you included 2 sets of I2C pads - one for a display and one for the temp/hum sensor?

[mlord]

Is that the reason you included 2 sets of I2C pads - one for a display and one for the temp/hum sensor?

A lot of things seem to want to connect to I2C, so yes I just duplicated the same four signals onto a second set of adjacent pads.  It's still the same I2C bus, regardless of which is used.

[dlwmacgregor]

I'm not sure that you've wired the IRF520 module correctly.  See this photo here for how to do it, thinking "heater" in place of "laser":
https://xunker.githu...ted resized.JPG

 

EDIT:  still too confusing. Here:

 

V+ and V- connect to the actual dew heater.

VIN & GND come from +12V.

 

SIG comes from the GPIO pin of the Arduino, through a diode.

VCC connects to nothing.

GND here connects to the Arduino GND.

 

Here's my own photo of the wiring:  https://www.cloudyni...-1683750248.jpg

On that picture it looks like the red wire connected to Vcc on the breadboard connects to something on the other end of the breadboard. What is it?

[mlord]

On that picture it looks like the red wire connected to Vcc on the breadboard connects to something on the other end of the breadboard. What is it?

It is connected to Vcc (3.3V) on the HBG3.  But not needed -- the end on the IRF520 module doesn't actually hook up to anything.  So just omit that unneeded wire completely.  The photo was just intended to show the 12V and heater connections on the IRF520 module.

[dlwmacgregor]

Roger that.