The HERMAN 6 control system will have a picaxe 28X1 processor as its heart. I did a lot of experimenting with this chip last year when it was released and I'm really impressed with its feature set and ease of programming.

What I intend to do is create a simple mother-board based on the 28X1 with many ways to extend functions with plug-ins. In part I've been inspired by the Make controller and Bug Labs, with an honourable mention for the Arduino. The Make controller is a mother-board with a heap of connectors for the outside world; the Bug Labs project is a collection of modules that you can plug together in any configuration depending on what you want your 'Bug' to do.

Below is a near finished schematic for the HERMAN 6 motherboard. I need to check through connectors and add a few components like capacitors on the voltage supply, and LED indication of power.

Essentially is it mostly connectors. I've chosen to use common dual inline connectors that clip onto ribbon cable without the need to solder (insulation displacement - IDC) for the ease of construction. It may seem strange to connect the pins of each side to one another (8-9, 7-10 etc.) but this is for ease of board layout. I don't need 16 connections on an IDC 16, and it also means that power supply capacity is increased should it need be (ie. for driving a motor).

The mother-board will be located underneath the control panel on HERMAN. The connection to the mash tun (hot liquor tun etc.) is via ribbon cable off these IDC connectors. Where feasible, these remote connections carry extended serial bus lines. The extended serial bus is there to allow simple expansion of inputs and outputs. In the future, if I decide to build a LED 7 segment display, I can plug it into the serial bus at the Mash Tun (or other location) and use it to show the Mash Tun temperature. The same bus can carry extra temperature probes or control a hop dropper or switch on the hot and cold liquor solenoids.

This all means that the parts for HERMAN don't need to be all built at the same time. The basic machine requires these bits:

• mother board (design nearly completed)
• Mash Tun board (simple design, nearly completed)
• Hot Liquor Tun, Heat Chamber, Kettle, Fermenter boards as per Mash Tun board (likely all the same design - if possible at least)
• control panel (buttons design complete, some work needed on the LED driver for the buttons)
• solid state relay board (complete and in use on current HERMAN machine)

As far as control code goes, the work done so far on HERMLET and the existing control code for HERMAN 5.5 should mean a simple transition to the new mother board.

I've been working through the DipTrace tutorial to get the hang of the program. Ultimately I want to be able to draw a schematic in picaxeVSM and export that into the DipTrace PCB program. For now, I'm learning how to use the DipTrace schematic so I've redrawn a small section of the Sea of keys encoder circuit.

But first I needed to create the component outline of the pushbutton switches with inbuilt LEDs.

Its not exactly great art, but the screenshot above shows the schematic representation of the switch and LED on the left, with air wires connecting it to the component outline on the right. This means I can draw a schematic of the encoder with my custom switch component, and then export to the PCB program without any trouble.

I knocked together a quick schematic of the Sea of Keys encoder with three switches and a connector.

This was then sent to the PCB part of DipTrace and after a bit of component rearranging, it looked like this with the air wires.

I then set a few parameters set on the autorouter. Because I am making boards at home and I want it to be as simple as possible, I chose 1 layer and allowed jumper wires. Then after about 30 seconds, the board was transformed into this:

I find this simply amazing, but I have not been working professionally with electronics for about 15 years now. Once the component outline and schematic were sorted, it took about 15 minutes to draw the schematic and produce the PCB outline above. What an incredible difference compared to my old program! It would have taken me hours to manually route a board like the one above using ExpressPCB. I still can't believe that DipTrace is free for up to 250 pin circuits. The autorouter alone makes it worth paying money for.

cheers, Arnie

When WindowsLive first went live it was a great opportunity to start blogging about HERMAN. I was frustrated, though, with some of the limitations - like only being able to upload small pictures which meant that schematic drawings were never legible.

I've just discovered a couple of big improvements. I can now upload a file and keep its original size intact (great for schematics) and I can now upload any kind of file for sharing.

The HERMAN blog site now includes a files section and to begin with I've added a couple of picaxeVSM files that I've been working on. If you don't have picaxeVSM you can still download the code files that match the circuits and have a look at the bitmap files of the circuit diagram.

The circuits uploaded are:

• sea of keys encoder - this is a resistive ladder and switch combination that allows you to put many switches onto one ADC picaxe input.
• 3x 7 segment LED display - this is a two part circuit. The sender picaxe reads a temperature probe and sends the data to a bus which can have potentially many receivers. If the ID code matches the receiving picaxe, the 3 digit LED display shows the resulting information. In this example it is a temperature reading to one decimal place, but it could be anything at all.

Also uploaded is the corel draw file and a bitmap of same of the current design for the new HERMAN control panel. This is the thing to replace the gaffer taped version . You can find that under the HERMAN 6 folder. The switches are pushbuttons with a circular LED built into them. The green rectangle with black border at the top of the drawing is a 40x2 LCD screen. There is a mock-up below of information that might be shown on the screen. The values in brackets are set points. The Hot Liquor Tun (HLT) has a set point of 80 degrees C and is showing it's actual temperature as 80.2 degrees. The 22% under the word MASH shows the amount of power being applied by the PID algorithm to the heat chamber. The timer is capable of a maximum timer of 99 minutes and 59 seconds.

If things go to plan, next week I'll post some more information on the design of HERMAN 6.

cheers, Arnie

The current HERMAN machine is running a patch-work of bits and pieces from old version 5 control hardware. It is currently being pressed into doing something it was never designed to do and it is literally sticky-taped together.

Version 5 used a picaxe 40X to communicate with a PC and read inputs and send control commands to an 18X picaxe. It was never designed to operate as ‘intelligent’ hardware without a PC coaxing it. This is a legacy of HERMAN history. The first machine used a 'dumb' analog interface hanging off a PC parallel port. All the processing was done in VB code on the PC. All the interface did was tell the PC what was happening or switch according to what the PC demanded. The version 5 interface used picaxes to make the interface digital (easier to use and less prone to analog noise). It was never designed to do its own processing, so the PC was still needed.

A key design parameter for HERMAN 6 is that its hardware will be capable of ‘stand-alone’ control. Too many ‘blue screens of death’ from Windoze and PC lockups meant that this was not simply luxury, but necessity.

The picaxe micros are capable of significant processing power. They can be pressed into PID control, for example. The hybrid patch-work interface we are currently using on HERMAN (5.5) is the old version 5 interface with a pushbutton panel that was prototyped for HERMLET. The picaxe coding is substantially different now, with PID worked out on board alongside other processing decisions.

The ultimate aim for HERMAN 6 (and therefore HERMLET) is for the picaxe controls to provide machine control that does not require a PC connected. A connected PC may be added to provide more complex control decisions towards the goal of automation.

So … some design ideas for HERMAN are on the drawing board.

And despite all that has been said about HERMAN, he still makes damn good beer. Cheers. Arnie

Probably the single most thing that cripples me when it comes to inventing, designing, creating is that I have too many ideas. This means that rather than figure out a design brief and stick to it, I have the tendency to figure out extra things I can add well into the design phase to ‘make it better’. I’ve blogged previously about the Simplicity Cycle but still find it a hard discipline to master.

One problem with having a fertile imagination is that sometimes the number of options available becomes overwhelming. Another problem is the lack of being able to focus on a single or simple plan of attack or order of things to do.

This is one reason I find blogging therapeutic. It forces me to commit (at least in bits and bytes) to an idea, or thread, or line of reasoning. It also helps to figure out what is really important.

Last November I hit a creative wall with HERMLET. Often time away is as good a dose of therapy as anything. One problem I had with the HERMLET project is that the first phase was too ambitious – despite attempts to keep it simple. It is a nice idea to create a machine that makes all-grain beer with the press of a few buttons. My problem was that I had confused end-user simplicity with construction simplicity.

To achieve the ambitious goal mentioned above, the coding demands on a picaxe were becoming overwhelming. It probably is achievable, and may well be the focus of further development, but to do it as a first step was too ambitious.

I need to keep telling myself that small steps are good. Working on a simple problem and getting it to work properly before attempting the next problem is good. Doing proper research (coding, components, asking questions etc.) is good. Working slowly is good.

Having the right tools for development is also a good thing. With the picaxeVSM program, I can literally work on small parts at a time and figure out code, circuit, components all at the same time, with the confidence that it will work right when made in reality.

So with the wall now dismantled, it is time to design and build.