The Wire Up

Listen while you read: Wilco - Impossible Germany


Elm Electronics is a small company that sells pre-programmed integrated circuits for a wide range of applications; around the home, electronics for your work bench and a few ICs just for fun.

They are most know for their automotive line of ICs that can interface with any vehicle that has an on-board diagnostic port, OBD1 and OBD2, and is one of 12 different protocols. The 12 different protocols are used by all domestic cars sold in the US and most foreign imports. There are very few vehicles not covered by Elms products. Soon, most car manufactures will all use the CAN (ISO 15765-4), which is supported by the Elm chip set.

There are quite a few variables, tests and trouble codes that you can capture using the OBD port of your vehicle but it all depends on the car manufacture and the protocol used.

Elm makes several different ICs based on the various protocols but has recently combined them all into one chip, the ELM327. The chip acts as an interpreter for your vehicles OBD port, it scans the port to find the protocol of your vehicle then returns the information it finds via RS232 or UART to directly connect to a micro-controller. It can even monitor the voltage of your vehicle.

Below is a demo board of the ELM327 . You'll notice that there is a lot of components required to run the chip. The circuit below includes the hardware for all 12 protocols, so if you know your only going to use the chip for one protocol then you only need the discrete parts for that particular protocol.

Elm Electronics does not provide any circuitry besides the IC, so you will have to design your own. If its not possible for you to design your own PCB or proto-board there are a plethora of devices built with the Elm automotive chip set. Search for Scan tool on Google. I'm using the ELM327 in my automotive data logger so if any would like some advice on implementing it into one of your projects I would be happy to provide some advice.

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Listen while you read: The Jon Spencer Blues Explosion - Do You Wanna Get Heavy


I have been staying with the fundamentals here for a while and today I'm going to continue the trend. Soldering a basic skill that any electronic hobbyist is going to want to acquire and for me it is actually the fun part of building electronics. It is a skill I think anyone can teach themselves and be good at, regardless of the caliber of tools they have. I don't have a hot air gun but I can solder fine pitch parts, it just takes a little practice. However, I would say there are tools that you just have to have. Another thing, you're going to make mistakes, you're going to mess up your pcb layout, solder something backwards or let the ghost out of your IC, so boy scout it and always be prepared. With all this said here's a list of the basic tools that I MUST have when starting any project. P.S. don't make fun of my messy desk, I can find out who you are!

Corded Weller Soldering Iron: You can own as many soldering irons as you want, but at the very least have a 12watt Weller soldering iron. I can't tell you how many soldering irons have gone bad in the past for me, but my 12watt Weller has never failed to work. I have left it running for DAYS and still it continues.

Solder: Now, I know that there is pressure coming to use silver solder. Silver solder is fine and I have been able to use it will all of my soldering irons. However, I would will always keep 60/40 tin/lead for prototype work. Its cheap and If you ever use any lead parts there is no point in using silver solder right?

Breaded Solder Wick: These next three are a follow up to what I said in the opening paragraph. You ARE going to make mistakes, be PREPARED. Copper braid is useful in soldering surface mount ICs with a plain old soldering iron.

Solder Sucker: You might think you can get away without this one if you have braid but I use this first when I start the removal of a part then use the braid. Sometimes I have to use the sucker again and then go back to the braid. Removing a COM port connection on a PCB can be difficult.

Flux Pen: When retouching parts this is a absolute necessity. I have even used this help in removal, it helps the solder become more viscous.

Wire Wrap: Again your going to make mistakes and when you screw up a trace on a pcb, the fasted and most discrete way to fix it is to wire wrap it. It might be hard to strip the wire, for that I use my teeth, but it fit between all types of pitches.

Alcohol: This is probable the one thing you can get by without having if your only using proto-boards, boards that set pattern predrilled holes with copper pads and traces underneath, for your project. Alcohol will clean any left over flux off your pcb helping in keeping your project running for a long time.

Safety Glasses: For safety's sake wear projection. I feel like a hypocrite, no, I don't wear them all the time, but you should!

Technorati Tags: Soldering Electronic Projects Emebed Electronics Flux Solder Wick Wire Wrap

Listen while you read: Radio Moscow - Timebomb

Over the past year in school I have spent a lot of time with the PSoC, Programmable System on a Chip. PSoC is manufactured by the company Cypress who's main focus is touch sense technology. The PSoC is the main controller for the click wheel in the Apple Ipod.

Leaning to program a micro-controller is a very big step in learning electronics. This is why I recommend to start out by trying PSoC. PSoC has a very unique interface compared with other micro-controllers, you begin setting up your system in a GUI rather then starting initialization in lines code. You are given a set number of digital and analog blocks. Programming is split up into two phases device editing and application editing. In Device mode you select the various device you want to include in your project then select there inputs and outputs, you can literally choose any pin on the chip to do anything you want it to. Any pin can be an input or output, digital or analog; Again anything you want. I have 4 different serial ports in my design, most micro-controllers only allow 2 or 3 at the most. They obviously cannot all run at the same time, if I wanted every port could be a serial port. The functionality is wonderful in PSoC. Take a look below at the interface for the device editor.

Now, the main purpose of the device editor is to make coding simplier and therefore allow you to focus on the purpose of your code instead of all the set up. So after we have installed and set up all our devices the next step is to write our application in C or assemble.

PSoC simplifies the process of writting code by shortening the commands for each device. This makes writting easier, plus each device has its own "data-sheet" with a list of commands to issue each device.

There are drawbacks with PSoC as there any micro-controller. PSoC is big and slow. Loading it with devices really slows things down. It has almost all functions as most other microcontollers; serial communication, ADCs, DACs, easy interface with LCDs. However, it takes forever to learn and you really have to spend a lot of time tinkering with it to understand it nuases, and sometimes you only can learn something by doing a very large project. There are alot of things its simplfing and theres a risk its coding things you will not need. I have heard of other compliers out there for PSoC that make the code much simplier. Despite these draw backs I think its a great system for a newbie to cut their teeth on or built in as a small part of a much larger system, such as its function in the Ipod. Hope you encounter it in the future it really is a great device and some such as myself does not give it enough praise and thourogh explaination.

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Listen while you read: Nada Surf - See These Bones

Here's the follow up post in the series of decoding component values. Ceramic caps are to easier to recognize then resistors, there is no silly saying to remember, which actually might be disappointing to some of you.

The labeling for ceramic capacitors is quite easy to remember, there are only 3 digits and a letter printed on the face of the cap. The first 2 digits stand for the value of the capacitor and the 3rd is the multiplier just like resistor coding. The only trick about the multiplier is you need to remember the base starts in pico farads. Pico, that's e-12. 102K on a capacitor would be equal to 1nF. Remember your units? Milli, micro, nano, pico.

The letter on ceramic caps stands for the tolerance. They are as follows:

C = ±0.25pF

J = ±5%

K = ±10%

M = ±20%

D = ±0.5pF

Z = +80% / -20%

Here's a more clear guide on interpreting ceramic caps.

That's it for ceramic caps. If you have any questions comment below or send me an email. Next post we'll take a look at the PSoC micro-controller which is actually used in the Apple Ipod.

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