1-Wire Fermentation Control System

[tharding]

Here is the Bluetooth/1-wire adapter that the host system talks to.
This prototype consists of 2 modules a bluetooth module and a power supply/1-wire module.

The bluetooth module receives the 1-wire commands from the host computer. On this board you can see the bluetooth chip and 2 leds. The greenish led indicates the connection status with another bluetooth device and the red led indicates when data is flowing through the module. The bluetooth ic is from Roving networks RN-41. This module can be configured over the air. The bluetooth ic supplies TTL level signals which are passed to the 1-wire module. The bluetooth ic is a Class 1 device and capable of a 100meter range.. Now if you are trying to go through walls, the distance will be limited. So those with 5,000 sq ft homes this module may not cut the mustard, if you are going from one end of the home to the other end.

The 1-wire module performs two functions a power supply. Supplying 5v to the 1-wire network and 3.3v to the bluetooth module and a 1-wire interface. There is a LM3940 which supplies the 3.3v for the bluetooth module. There is also a DS2480B which is a serial port to 1-wire interface ic. It connects directly to the bluetooth module. The module also has a DS9503 an ESD protection device for 1-Wire interfaces.

The transistor(mosfet) sitting off by itself at the top of the picture was an additional mod I made to the system, where I can send the bluetooth module a command to toggle
one of its outputs which then grounds the VDD pin on the 1-wire interface chip. Basically giving me power reset capabilities if the 1-wire communications ever go haywire.

I know there won't be many of the members creating bluetooth/1-wire interface boards, but it is not necessary.

You can eliminate the bluetooth module completely. You just need to connect the 1-wire network directly into the host computer. I wanted a wireless solution so I could one day use the 1-wire setup to control my mashing process.. For fermenting, my kegerator and fermentor are in my office next to my computer, so if I wanted I could connect everything directly to the computer. We can explore this option later if others are interested.

 

[mxc1090]

tharding:

What process do you use to etch? (I use laser transfer/iron with muriatic acid and H2O2)

Does this connect directly to rs-232?

What are you using on the host computer to read the serial data?

Any fears of having AC and DC so close together in the same box (aside from being against electrical code)?


I do have one qualm with your setup: you are sending 5v through a phone line to the relays (>100mA a piece, correct?). I believe the only reason this works is because of the short length of the cable. If I had the 5V power supply on the other side of the room, it probably would drop the voltage too much, right?

I wouldn't be doing x-10, but I would have a spare laptop in the brew area and just wire everything up through that and then online. I have been going through an arduino for my 1-wire setup and reading the serial data in processing, but considering I can get the DS2480B as a free sample I might try it out.

Awesome setup. You MUST keep adding more things. Ever consider the cheap RF modules? http://www.sparkfun.com/products/9582

or hooking the output directly to a dd-wrt router with serial setup?

 

[spearko520]

This looks awesome! - i'm going to have to look into the one wire thing- i'm not sure but maybe it's similar to the 0-10 VDC that our ATC guys usually use for control circuits. I currently use a chilled glycol loop (the coil is in the freezer section of a refrigerator) and a pump to cool an insulated cabinet that houses kegs. A space temp controller currently maintains the temp, but I can kind of see an application here (using your ideas) for some additional controls and maybe an add on for more fermentation space... keep us posted and keep up the good work!!!

 

[dbrewski]

ok dbrewski, lets bring you back into the game. I totally forgot about my first versions of the system. In the first version before I developed the 1-wire 10v switch I was using x10 technology to switch the pump on and off.

X10 huh? I will look into this. I have a couple projects to finish up but thanks for the tip!

 

[tharding]

tharding:

What process do you use to etch? (I use laser transfer/iron with muriatic acid and H2O2)

I do the same. I have been using kodak high gloss photo paper for the printing medium. I want to try clear overhead projector film when I attempt to do a double sided board.

tharding:
Does this connect directly to rs-232?

Not sure what this is? If you are talking about the RN-41 bluetooth ic.. It does put out rs-232 formatted signal at TTL levels. You would need to add a RS-232 driver to connect to a RS-232 port

tharding:
What are you using on the host computer to read the serial data?

I am using maxims java 1-wire api library to communicate via the bluetooth serial port on the host computer.

tharding:
Any fears of having AC and DC so close together in the same box (aside from being against electrical code)?

No fears. Just lots of caution when working with 110v AC. Each socket is limited to 5A. The ground and neutral wires go directly to the sockets and the power line is switched by using mechanical relays. Of course the power module would probably not get a UL rating, but I am not looking at manufacturing them for resale and anyone building one does so at their own risk. I am sure the box could be redesigned to actually meet UL code standards. Again I consider the power box to be like a power supply module that plugs into the wall.

tharding:
I do have one qualm with your setup: you are sending 5v through a phone line to the relays (>100mA a piece, correct?). I believe the only reason this works is because of the short length of the cable. If I had the 5V power supply on the other side of the room, it probably would drop the voltage too much, right?

First the bluetooth module is meant to sit near the power module and the temp sensors not sitting across the room as that would defeat the purpose of eliminating the wire from the host computer to the bluetooth module.
Now lets explore the electrical aspects.
Cat 3 telephone cable contains AWG 24 solid wire which has a DC resistance of 0.0302 ohms per foot. If we had a length of cable 50' long, we would calculate the distance * 2 for the ground return, giving us a 100' length of AWG24.. which calculates out to 3.02 ohms. Now the relays I am using are 5v relays which operate at 89 ma each for a total of 178 ma if both are operated at the same time. Which would give us a voltage drop of
(v = IR) or 0.538v. So now my supply voltage is sitting at 4.5 v. still plenty of voltage left to operate the sensors and bluetooth module. The 1-wire sensor will operate down to a voltage of around 3.0v and the bluetooth ic likes 3.3v and the relays will operate down to 3.5 volts. So we could still operate everything at a distance of 50' axway from the power source.

tharding:
I wouldn't be doing x-10, but I would have a spare laptop in the brew area and just wire everything up through that and then online. I have been going through an arduino for my 1-wire setup and reading the serial data in processing, but considering I can get the DS2480B as a free sample I might try it out.

The point of the x10 module was to be able to remotely wirelessly control a 110v device from a computer. I accomplished this by building the power module, but those who don't have the skills to do circuit boards and want to buy an off the self product can use x10. I have in the past and it works just fine for turning the pump on and off.

Do you know of any 110v switching device that can be controlled by a computer program?

tharding:
Awesome setup. You MUST keep adding more things. Ever consider the cheap RF modules? http://www.sparkfun.com/products/9582

or hooking the output directly to a dd-wrt router with serial setup?

Thanks.. It is great posts like yours that make us think hard about our setups and if there is anything else we could do differently.

You know I haven't. Before the bluetooth idea, I connected the 1-wire network directly to the host computer and communicated with the sensors via the serial port, using maxim's serial port adapter. I wanted to get rid of the wire running across the room so I dreamed up the bluetooth/1-wire module to eliminate the connection to the host computer. The 1-wire adapter also did not supply 5v to the network. By using bluetooth and its virtual serial port mode SPP I did not have to make a single change to the controlling software.

 

[tharding]

I currently use a chilled glycol loop (the coil is in the freezer section of a refrigerator) and a pump to cool an insulated cabinet that houses kegs.

chilled glycol loop.. Sounds interesting.. I could eliminate the keg of water in the kegerator to make room for another keg of beer..

I can see copper tubing pressed against the cooler plate in the back of the kegerator cooling the glycol and an inline pump cycling the glycol through the system.

Maybe this will be a new mod in the future. At least I now know someone to hit up for info on using/where to buy glycol.

 

[mxc1090]

First the bluetooth module is meant to sit near the power module and the temp sensors not sitting across the room as that would defeat the purpose of eliminating the wire from the host computer to the bluetooth module.
Now lets explore the electrical aspects.
Cat 3 telephone cable contains AWG 24 solid wire which has a DC resistance of 0.0302 ohms per foot. If we had a length of cable 50' long, we would calculate the distance * 2 for the ground return, giving us a 100' length of AWG24.. which calculates out to 3.02 ohms. Now the relays I am using are 5v relays which operate at 89 ma each for a total of 178 ma if both are operated at the same time. Which would give us a voltage drop of
(v = IR) or 0.538v. So now my supply voltage is sitting at 4.5 v. still plenty of voltage left to operate the sensors and bluetooth module. The 1-wire sensor will operate down to a voltage of around 3.0v and the bluetooth ic likes 3.3v and the relays will operate down to 3.5 volts. So we could still operate everything at a distance of 50' axway from the power source.

RIght. After looking at the spec sheet for my 10A 5V relay, I noticed a minimum 'turn-on' value around 3V

Do you know of any 110v switching device that can be controlled by a computer program?

Not off the top of my head, but I could probably figure out how to make one with tan arduino + processing (kind of the only programming I know)

Thanks.. It is great posts like yours that make us think hard about our setups and if there is anything else we could do differently.

Cheers to you for starting the discussion!

 

[tharding]

Not off the top of my head, but I could probably figure out how to make one with tan arduino + processing (kind of the only programming I know)

I like to program pic microcontrollers using a product called JuneBug and Microchip MPLab IDE.

When developing the 110v controller I thought that a microcontroller was not the way to go and 1-wire was a better fit with a software program polling the sensors and activating the 110v module.

Now if I was going with a dedicated controller panel, it probably would have several microcontrollers all communicating with each other.

So many different ways to slice an apple..