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Equipment Discussions >> Equipment

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bassplayer142
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Reged: 10/03/11

Loc: Michigan
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5410321 - 09/08/12 03:46 PM

Not sure what you mean by clunky movement of the pot and that a 5k Would be better. Is that a logarithmic pot? Another added feature would be automatic power supply detection and shutoff so that batteries are not over drained.

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Pauls72
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Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: bassplayer142]
      #5411113 - 09/09/12 03:14 AM

By clunky I mean the output is not smooth and jumps around as you adjust it. I was thinking the Arduino probably has some type of pull up/down resistors as part of the chip on the data lines and the 100K might be to large to over come this if they are a lot lower value.

The pot is a 100K trim pot from Radio Shack. It doesn't specify anything, so I assume it's linear.

Well I dragged my scope out of the garage attic and took a look at it. The voltage spikes up/down or even doesn't move at times while adjusting the pot. So it looks like it is just a cheap junky pot.

Well I'm pretty happy with my current version of the code.
http://michiana-astro.org/projects/dewctrl/DewCrtl3_20120908.pdf
Changes are:
There is now an option to display the temperatures in Fahrenheit or Celsius. I didn't change any of the logic, so everything in the background is still done it Fahrenheit. You just change one Boolean constant in the source.
Cleaned up the debug output to the USB serial port.
Rewrote the duty cycle and scroll logic to drive the straps at a higher frequency and have the display scrolling smoother and consistent.
Duty cycle is now adjustable between 0 and 100%.

Yea, I thought a little about a low voltage detect. Let me think about some kind of simple voltage sense circuit I could make to feed an analog input. My electronics theory is pretty rusty as I haven't used it in years.


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mitaccio
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Reged: 03/17/09

Loc: Oahu, Hawaii
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5411774 - 09/09/12 02:47 PM

I am curious about your putting the DHT11 on the outside, venting the case, and putting heat sinks on the tip120's. Were you experiencing thermal issues inside the case? What size heater straps are you using on the tip120's? Have you found the DhT11 is affected by being inside the case and having only the face exposed? Have you tried both mounting locations and found differing results?

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bassplayer142
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Reged: 10/03/11

Loc: Michigan
Re: How to make an automatic dew controller - Arduino new [Re: mitaccio]
      #5411942 - 09/09/12 04:50 PM

Trim pots are notoriously noisy. Although they work, they are mainly used for single time adjustments/tuning. A larger pot would be cleaner for sure.

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Pauls72
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Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: mitaccio]
      #5411999 - 09/09/12 05:26 PM

I did not even try the DHT-11 inside the case, I may later. I just attached with a a few dab's of adhesive from a hot glue gun. I have it on 3" of ribbon cable.

I just have 3 dew straps at the moment:
11" - DN11, 18.8W, 1.49A (C11)
4" - DN05, 7.3W, .61A (120mm MAK)
2" - DN03, 4.1W, .31A (2" eyepiece)

I took heed of your note of concern for over driving the TIP-120's at 1A. "Note: the TIP120s are meant to handle a max of 1amp. So make sure your heaters don't surpass!" Even though the transistors I used are rated at 5A, I figured the heat sinks would be good insurance. With the heat sinks, I can now use what ever size straps I want and never have to worry. But due to space limitations I only have 2.

Venting the 2 rear filler plugs was no big deal. If I have heat sinks, I figured venting would help too. I didn't go crazy with venting, just did the black filler plugs.

Edited by Pauls72 (09/10/12 10:47 AM)


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Pauls72
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Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: bassplayer142]
      #5412026 - 09/09/12 05:47 PM

A 10 or 15 turn trim pot would work much better, but at night in the dark who would want to be cranking and cranking on a pot. I am slim on room inside the case to put a larger size pot.

All the old electronics stores I used to buy stuff from are gone. So it is pretty much Radio Shack or mail order. I was up at Fry's outside Chicago last weekend getting some PC parts, they have ton's of empty peg's in the electronics dept.


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Pauls72
professor emeritus
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Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5414250 - 09/10/12 10:12 PM

Well I found out today the pdf's I previously created and posted have a number of truncated lines. So here is my current version in PC text format and an Arduino .ino source file.

PC-Text: http://michiana-astro.org/projects/DewCtrl/DewCrtl3_20120909.txt

Source: http://michiana-astro.org/projects/DewCtrl/sketch_DewCrtl3_20120909.zip

Last 2 sets of changes:
Sept 9, 2012 - Version 3.4
Added in storing of high and low values of all sensors in EEPROM. Sorry this part is all in fahrenheit at this time.
Added clearing of EEPROM Dew Destroyer variables with two consecutive powerups or rests with no Dallas one-wire sensors connected.
Added in the ability to run without the duty cycle input pot.
Added in the ability to run without the Voltage detect divider resistors.
Fix a bug in the duty cycle logic.

Sept 8, 2012 - Version 3.3
Added in Voltage Detect and display to the screen.
If low voltage is detected > 11.6V the turn off outputs and stop processing almost forever (400000000 miliseconds or just over 111 hours).
Using a USB cable only to power the Aruindo portion of the project, may result in low reference voltage on the Arduindo board and low or wrong voltage readings.
Added operational time to the screen (time since power up or last reset).
Removed S= number of sensors found from the screen. Information was redundant.

I have added a simple voltage divider network of resistors for voltage detect input. Why did I use 2.2K Ohm resistors, because that's what I had in my parts junk box. I used the 25% of the heater voltage and an input to analog pin 1 (A1). The Arduino has a 5V reference that it uses built in.



A couple of pictures of the inside. There are 2 transistors on heat sinks under the rats nest of wires. The other 2 transistors are on the right side. The 4 large bullet diodes are along the left side.






I was looking and there is an Arduino shield that has an RGB LCD display (color) and 5 buttons. It only used 2 data lines to connect to the Arduino. I was thinking if you drove the display in red it should work for the display and with the 5 buttons you could select all kinds of options/menus. Since it only uses 2 data lines, it frees up some additional digital ones for data input/output. On the down side you would have 2 shields stacked and with the display stacking right on-top of the Arduino you would have to use a different case.

Color LCD Shield: http://www.adafruit.com/products/714


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Pauls72
professor emeritus
*****

Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5414290 - 09/10/12 10:38 PM

I you click on this picture you can watch the updated video.



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mitaccio
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Reged: 03/17/09

Loc: Oahu, Hawaii
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5414300 - 09/10/12 10:44 PM

I really like the LCD shield, but see one issue I hope they resolve: there isn't a PWM control for the backlight. The display may be too bright for astronomical use. But the 2 pin use is a great idea, couple that with the 5 buttons and it has great potential.

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Pauls72
professor emeritus
*****

Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: mitaccio]
      #5415539 - 09/11/12 03:38 PM

I noticed the temperature results of my DHT-11 sensor always drifted up over time. I still have it external to the case and I have some space under it for air flow. As a test, I left it running overnight on the counter and had all 4 Dallas one wire sensors right by the DHT-11. This morning when I got up it showed it was 8F over the the 4 Dallas sensors. I turned it off for an hour or so and then all 5 sensors where the same again. This was with it running about 7 hours.

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Pauls72
professor emeritus
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Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5418155 - 09/12/12 09:42 PM

Sept 11, 2012 - Version 3.5
High and low temp are now stored in Fahrenheit or Celsius, which ever has been selected.
Correct a previous error I made storing some of the values.
Change sensor high/low storage values to a function.
Change low voltage detect to recover and continue in the event of a low voltage spike.
Make Voltage reading a function.
Start working on cleanup of the code.
Current limitation I found this evening, can not store temperatures below zero.

PC-Text: http://michiana-astro.org/projects/DewCtrl/DewCrtl3_20120911.txt

Source: http://michiana-astro.org/projects/DewCtrl/sketch_DewCrtl3_20120911.zip


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Pauls72
professor emeritus
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Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5420837 - 09/14/12 12:18 PM

Sept 13, 2012 - Version 3.6
Offset sensor values stored in EEPROM by 100 to allow for negative numbers. Value range is now from -99 to +155 for all sensors.

PC-Text: http://michiana-astro.org/projects/DewCtrl/DewCrtl3_20120913.txt

Source: http://michiana-astro.org/projects/DewCtrl/sketch_DewCrtl3_20120913.zip


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Pauls72
professor emeritus
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Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5455016 - 10/04/12 12:26 PM

I have added a RTC (Real Time Clock) and EEPROM (external non-volatile memory) module. What I purchased was a Tiny I2C RTC DS1307 and 24C32 module @ $6.00. There are sever different versions of this board being sold with different combinations of the following three components:
DS1307 - RTC (Real Time Clock with about 50 bytes of it's own EEPROM)
24C32 - EEPROM 32K bit (4K x 8bits or 4K byte).
DS18B20 - Dallas One-Wire temperature sensor.

This module's sells for between $4 and $33 depending who you buy it from. I got mine from Deal Extreme, the only bad thing is the long wait of 10-14 days for shipping.
http://dx.com/p/tiny-rtc-i2c-24c32-ds1307-real-time-clock-module-for-arduino-146677?item=1



The devices are simple to hook up as they use 2 analog pins to communicate over a serial bus using the I2C Philips protocol and the wire.h library.
SDA - Analog pin 4 (A4)
SCL - Analog pin 5 (A5)

DS - Digital pin 3 (D3) connection is optional and would only be used if you have a DS18B20 temp sensor on the board. I see no need for this as there already is the DHT11 to measure temp at the unit. It would also require additional program changes to accommodate a fifth Dallas On-Wire sensor. This sensor would be in parallel with the other 4 Dallas On-Wire sensors for the OTA's, Eyepiece and Aux.



Each device on the I2C serial bus has a unique address and there can only be one of each of the devices per serial bus.
DS1307 = 0x68 (104)
24C32 = 0x50 (80)

The 24C32 EEPROM is a slow device when compared to the Arduino and as I found out the hard way it required some delays to prevent extraneous results.

Right now I give the Dew Controller 15 seconds to stabilize and then save all the values to EEPROM memory. After that I save off the values every 15 minutes (900000 milliseconds) for as long as the Arduino is powered up. Four times an hour just seemed like a reasonable number without being over kill. at 4K you can have 341 sets of data entries 341 x 12 bytes = 4092. I leave a set of blank entries every time the Dew Controller is powered up, this makes it easy to locate. Using the Arduino IDE USB Serial Terminal you can dump the EEPROM memory to the screen and then copy and paste it into a .csv file. This allows you to use the data with a spread sheet program like Excel and then graph the data. There has been several concessions that I made to save on memory, I do not save the year as part of the date and I do not save the seconds in the time. Additionally the voltage is rounded to a single decimal place. Here is an example of what the data looks like:

Dumping stored values
'Current Position = 528'
Memory location,Month/Day,Hours:Minutes,S1,S1,S3,S4,Temp,Humidty,DewPoint,Volts
Address=0,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=12,10/3,21:36,77,77,77,76,78,42,55,13.10V
Address=24,10/3,21:50,77,77,77,76,77,42,53,13.10V
Address=36,10/3,22:5,77,76,77,76,78,42,55,13.10V
Address=48,10/3,22:20,77,76,77,76,78,42,55,13.10V
Address=60,10/3,22:35,77,76,77,76,78,41,54,13.20V
Address=72,10/3,22:50,77,76,77,76,78,41,55,13.20V
Address=84,10/3,23:5,77,76,77,76,78,41,54,12.90V
Address=96,10/3,23:20,77,76,77,76,78,41,54,12.80V
Address=108,10/3,23:36,77,76,77,76,78,41,54,12.80V
Address=120,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=132,10/3,23:41,77,76,77,76,78,41,54,13.00V
Address=144,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=156,10/3,23:52,77,76,77,76,78,41,54,13.20V
Address=168,10/4,0:6,77,76,77,76,78,41,54,13.20V
Address=180,10/4,0:21,77,76,77,76,78,41,54,13.20V
Address=192,10/4,0:36,77,77,77,76,78,41,54,13.20V
Address=204,10/4,0:51,77,77,78,77,78,41,54,13.20V
Address=216,10/4,1:7,77,76,77,76,77,40,52,13.20V
Address=228,10/4,1:22,77,77,77,77,77,41,52,13.20V
Address=240,10/4,1:36,76,76,77,76,77,40,52,13.30V
Address=252,10/4,1:51,77,76,77,76,77,41,52,13.20V
Address=264,10/4,2:6,76,76,77,76,77,40,52,13.30V
Address=276,10/4,2:21,76,76,77,76,77,41,52,13.30V
Address=288,10/4,2:36,76,76,77,76,77,40,52,13.30V
Address=300,10/4,2:52,76,76,76,75,77,40,52,13.30V
Address=312,10/4,3:7,76,75,76,75,75,41,51,13.30V
Address=324,10/4,3:21,76,75,76,75,75,41,51,13.30V
Address=336,10/4,3:36,75,75,76,75,75,41,51,13.40V
Address=348,10/4,3:51,75,75,76,75,75,41,51,13.40V
Address=360,10/4,4:6,75,75,75,74,75,41,51,13.40V
Address=372,10/4,4:21,75,75,75,74,75,41,51,13.40V
Address=384,10/4,4:37,75,75,76,75,75,41,51,13.40V
Address=396,10/4,4:52,76,75,76,75,75,41,51,13.50V
Address=408,10/4,5:6,75,75,76,75,75,41,51,13.40V
Address=420,10/4,5:21,76,76,76,75,75,41,51,13.50V
Address=432,10/4,5:36,75,75,76,75,75,41,51,13.50V
Address=444,10/4,5:51,76,75,76,75,75,41,51,13.50V
Address=456,10/4,6:6,75,75,76,75,75,41,51,13.60V
Address=468,10/4,6:22,76,75,76,75,75,41,51,13.50V
Address=480,10/4,6:36,76,75,76,75,75,41,51,13.60V
Address=492,10/4,6:51,76,75,77,75,77,41,52,13.50V
Address=504,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=516,10/4,6:57,77,76,77,76,77,43,53,13.70V
Address=528,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=540,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=552,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=564,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=576,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=588,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=600,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=612,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=624,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=636,0/0,0:0,0,0,0,0,0,0,0,0.00V
Address=648,0/0,0:0,0,0,0,0,0,0,0,0.00V


Oct. 3, 2012 = Version 3.8
Add support for DS1307 RTC module.
Add support for 24C32 EEPROM (32K bits - 4kx8).
Replace limited data storage of EEPROM with larger I2C_EEPROM.
Added date and time to the saved data.
Reworked the save data routines.
Blank entry to indicate power up.
Save readings after the system has about 30 seconds to stabilize and then every 15 minutes after that.


Sept 17, 2013 = Version 3.7
Save off high and low voltages to EEPROM.
Added Serial commands sent through USB ATE or Ardino Serial Terminal (D or d to dump EEPROM memory, Z or z to zero out EEPROM memory, P or p to pause for 30 seconds).
Data in dumped in a format so you can copy and paste it in a csv file to use with a spread sheet.


PC-Text: http://michiana-astro.org/projects/DewCtrl/DewCrtl3_20121003.txt

Source: http://michiana-astro.org/projects/DewCtrl

One thing I have found that seems to pretty common is that documentation, libraries and example programs for all the different modules and devices is skimpy at best, sometimes wrong and a lot of time won't compile and if it does, it doesn't work or only partially works. The datasheets for the devices (if you can find them) are your best reference materials.

I am planning to hook an IR remote to let you set all the dew controller options without a computer and without adding buttons to the controller. You would also be able to control the LCD contrast and duty cycle and no longer require the (2) 100K trim pots. But unfortunately I let the factory smoke out of the IR sensor module. I have a couple of new ones on order.
http://dx.com/p/ir-receiver-module-wireless-remote-control-kit-for-arduino-1-x-cr2025-135520?item=2


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UmaDog
Carpal Tunnel
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Reged: 09/15/10

Loc: Basel, Switzerland
Re: How to make an automatic dew controller - Arduino new [Re: Pauls72]
      #5462727 - 10/09/12 07:33 PM

This looks awesome. I've recently started working on Arduinos for work so I'm tempted to give this project a go next.

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Pauls72
professor emeritus
*****

Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino new [Re: UmaDog]
      #5463155 - 10/10/12 12:10 AM

If I had it to do over, there are 2 things I would change:

1) I would use a DHT22 sensor instead of a DHT11. It is more accurate and has a larger working range. It gets well below 0C (32F) here in the winter. They have the same pin out, signal and power requirements, but the DHT22 is double the cost of the DHT11.

DHT11
Good for 20-80% humidity readings with 5% accuracy
Good for 0-50C temperature readings 2C accuracy

DHT22
Good for 0-100% humidity readings with 2-5% accuracy
Good for -40 to 80C temperature readings 0.5C accuracy

2) I would one of these boards to reduce the number of wires to the display.
IIC/I2C/TWI/SPI Serial Interface Board Module For Arduino 1602 LCD Display 5V
http://www.ebay.com/itm/221126389469?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

The biggest obstacle I had was in my initial learning of the Arduino was the large number of different versions of the libraries and example code. The fact that some of these don't compile, do not work at all or work with limited or intermittent results made the learning curve that much steeper.

The fact that you are already working with Arduino's will give you a leg up on most people.


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ThadeusB
member


Reged: 11/14/12

Loc: Somerset, UK
Re: How to make an automatic dew controller - Arduino [Re: Pauls72]
      #5532805 - 11/21/12 06:49 PM

Help please someone!

My sketch has the line:

dht22 DHT22;

The IDE compiler throws up an error:

error:'DHT' does not name a type

I don't know how to sort this one out, can anyone help please?

Thanks


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Pauls72
professor emeritus
*****

Reged: 10/28/07

Loc: LaPorte, IN
Re: How to make an automatic dew controller - Arduino [Re: ThadeusB]
      #5532823 - 11/21/12 07:06 PM

I assume your using the DHT11 library or do you have one for the DHT22?
#include <dht11.h>

If you are using the DHT11 library replace the line with this line.
dht11 DHT11;
Also replace all your references to DHT22 with DHT11.

I believe both devices use the same protocol etc... so they can use the same library.

If you can't get it working, zip up your sketch and libraries and send them to me and I'll take a look at it.


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ThadeusB
member


Reged: 11/14/12

Loc: Somerset, UK
Re: How to make an automatic dew controller - Arduino [Re: Pauls72]
      #5535662 - 11/23/12 02:45 PM

Thanks for replying Paul. I have the adafruit library for both DHT11 and 22.

Someone else told to replace the: 'dht DHT' line with this:

#define DHT22PIN 2
#define DHTTYPE DHT22
DHT dht(DHT22PIN, DHTTYPE);

This got me passed the problem I flagged up. But now there are are problems in the main program loop.

However, I will certainly try what you suggest and let you know the result.

Many thanks for offering to look at my sketch; I appreciate that.

Phil


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ThadeusB
member


Reged: 11/14/12

Loc: Somerset, UK
Re: How to make an automatic dew controller - Arduino [Re: ThadeusB]
      #5535703 - 11/23/12 03:10 PM Attachment (34 downloads)

Hi Paul,

Well, I did as you suggested, but no luck. It stall at 'dht DHT'. With many other compile errors. So


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ThadeusB
member


Reged: 11/14/12

Loc: Somerset, UK
Re: How to make an automatic dew controller - Arduino [Re: ThadeusB]
      #5535709 - 11/23/12 03:12 PM

Paul, something went wrong with the last message. So I'll try attaching the zip file again.

Very many thanks for offering to help. I'm out of my depth with this!

Phil


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