isaachenry.com

Arduino Grapher beta release

Wed, 02 Nov 2011 03:45:00 GMT

I have finally finished the Arduino up to a stage that I can release a beta.

You can download it here

More info including installation, hardware setup and usage are included in the documentation.

Here is a short video showing the capabilities of the application:

Known Bugs:

For smaller resolution screens the app will hang out the bottom of the window. Usually this isn't a problem.

If more than one device identifying as a serial port is connected, the app won't find the arduino unless it is the first one plugged in

How to stop arduino resetting

Tue, 18 Oct 2011 12:00:00 GMT

I found buried in an article on the arduino forums a technique of stopping an arduino from resetting when a serial connection is established - simply put a >100nF capacitor between GND and RESET. The arduino will no longer reset :)

Arduino Grapher progress

Mon, 17 Oct 2011 12:00:00 GMT

I have now committed the current progress to Github - https://github.com/xiphiaz/Arduino-Debugger

Since the last post I have expanded the project from just interfacing individual sensors, to tracking the activity of all the pins on the arduino. This will allow users to have their own project code running on an arduino, and connect another Arduino running my software to the first one. The benefit of this is that the user will be able to check on their own code, to see that the digital pins are going high when expected, and that the analogue pins are receiving the expected values.

One thing I would like to add is to give the grapher the ability to draw in 3D, which would be very useful for checking on multi-axis sensors.

I initially looked in to using firmata for the sketch on the probe arduino, however I quickly realised that firmata wouldn't be suitable as it does not provide good timestamping on the messages, which is important for graphing accuracy. Also as firmata uses the MIDI protocol there is significant overhead on the size of the packets, which would limit the quantity of data crossing the serial interface, which would drop the polling frequency to an unacceptable level.

Because of the limitations of firmata I have developed my own sketch that simply has a start/stop command and the ability to turn on/off individual pin reporting. A sample io would look like the following:



>{pin_on:a0}

>{print:begin}



[123456]{a0:127}[123472]

[123476]{a0:132}[123483]

[123497]{a0:195}[123503]

The returned message is fairly lightweight, so a lot of data can be sent at high rates, and will be easily parsed by the master software.

I have also been developing a method of changing the baud rate on the fly, as when lots of data is being passed through the serial interface polling rate drops. By upping the baud rate it is possible to get a higher throughput of data, at the cost of cpu cycles on both the arduino and the host computer.

Smart Systems - New Idea

Sat, 24 Sep 2011 00:00:00 GMT

Now that I have abandoned my curved PCB idea I am moving on to another idea that I have had.
One of the biggest frustrations with programming arduino is the lack of feedback from the more complex analogue sensors. Programmers find themselves staring at streams of numbers coming from the serial console trying to make sense of the data at the rate it is coming in (and at the rate that they can process it).

There is clearly a need for a program that graphs the pin data from an arduino so that the hardware developer can easily make informed decisions on how to handle the information that the input device they are trying to interface.

This program should make it easier for developers to interface the notoriously difficult sensors such as gas, magnetometer and accelerometer sensors. The brief is to make a hardware device to assist people in working with electronic hardware, and this program should meet the brief as it will require a hardware component to interface the sensor.

Changing focus

Tue, 20 Sep 2011 12:00:00 GMT

I have had little luck with getting the copper to deposit properly. Here is a video showing the technique I tried which has the cathode as a huge piece of copper with the work anode inside it. The idea was that the copper would be pulled off the copper, and deposit onto the work piece.

I have had successes with the process, however I am still a long way off having anything close to usable for a PCB. As I am no chemist, I am unsure of the reasons why I am having failures - too much current, wrong voltage, poor quality water and bad seed conductivity are some of the many problems that could affect the outcome.
With so many variables don't believe I will be able to find a suitable technique within the deadline. As a result I have decided to completely change tack with the paper and shelve this project for the time being.

Semi successful copper deposit on curved plastic

Tue, 30 Aug 2011 12:00:00 GMT

By following the Popular Mechanics article I was able to successfully deposit copper onto a film canister. There is still significant issues with the technique that will need resolving before the technique is viable for depositing copper for PCBs.

The process is shown below:

Melting candle to get paraffin for coating plastic

Coated film canister allowed to dry

Mixing carbon powder with water to a paste consistency for coating

Brushing canister with dry powder for base layer

Coating canister in carbon paste

Mixing in CuSO₄ crystals

Canister connected to electrodes and submerged in solution

The biggest issues with the technique is that there can only be so much copper suspended in solution, and once that copper has been pulled out of solution and deposited, there is no copper left. I need to find a way to add copper to the solution at the same rate that it is pulled out of solution.

The other issue is that while the paraffin provides a good surface for coating, it is also a very weak wax. After a short time the deposited copper layer flakes off the plastic, which would be completely unsuitable for making a PCB. Also I am concerned what would happen to the wax later in the PCB process where acid is used to etch away the copper.

First attempt at depositing copper

Fri, 26 Aug 2011 00:00:00 GMT

For the first attempt at depositing copper I went with the classic copper deposit on coin experiment.

Depositing copper on coin

I did this so that I could work out good settings for the voltage/current. This test was successful, and I did a test to if the conductivity of the deposited copper was low enough for making a PCB.

Measuring conductivity of flaked off copper

The Popular Mechanics article required carbon powder to be put on the non-conductive object to give a base conductivity for the first ions of copper to bind to. As I didn't have any carbon powder I tried grinding up a pencil, and rubbing it onto the sticky side of masking tape. After about 30 mins of plating the masking tape had a deposit of copper, and the conductivity across the tape was still perfect.

For the next test I will get some carbon powder and follow the Popular Mechanics article exactly

Curved printed circuit boards

Wed, 24 Aug 2011 12:00:00 GMT

For smart systems we have to develop a hardware project. We have been looking into how to produce printed circuit boards with really simple DIY techniques.

The process is relatively simple, and instructions on how to do it can be found anywhere on the web.
From the outset of the project I have been interested in the limitations of printed circuit boards, especially when considering the massive quantity of PCBs in the world.

One of the things in common with all printed circuit boards is that they are flat. Invariably PCBs are printed directly on a flat surface. Occasionally there are daughter boards that sit at a right angle to the parent board, but there are no PCBs that are printed on a curved surface.

Having curved PCBs would be very useful to the technology industry as it would allow design freedom for products that require PCBs, rather than having to shape the product around the rectangular board.

There is already many techniques for printing on curved surfaces, so I saw the difficulty with curved PCBs in depositing the thin layer of copper onto the fibreglass substrate.

I'm going to attempt to develop a simple method of creating curved printed circuit boards. From preliminary research I have found a technique outlined in the 1925 Popular Mechanics magazine, which demonstrates how to deposit metals onto inorganic surfaces. I will attempt to give this method a go.

OP-1 Hex Sequencer Release

Mon, 08 Aug 2011 23:56:18 GMT

At last I have a useful application to release for my OP-1 midi library. This is a sequencer which works by sending notes around a hexagonal grid, with the notes being triggered when going through activated hexagons.

All the controls are colour coded as per the OP-1's rotary encoders. Blue controls the selected hexagon, and pressing the blue encoder toggles the hex trigger status. Green controls the main turret, which defines where the note will go next. White controls the secondary turret which, if active, will control where the note will go next. When two turrets are active the incoming notes alternate which turret's direction to take.

This app should work in MacOSX 10.6 (Snow Leopard) and might work on 10.7 (Lion).

Download it here

OP-1 MIDI Mate alpha release

Sat, 30 Jul 2011 21:41:29 GMT

My first public application! OP-1 MIDI Mate is a simple graphical display of the OP-1 MIDI IO.

Download it here

Please note this is an Alpha release, meaning that is is probably non-functional on a few computers. It should work on OSX 10.6 (Snow Leopard) and later. I haven't yet tested for Lion though. I tested it on a mac pro running 10.5 server, and it crashed instantly as expected. If you are 10.5 or below, sorry.