SparkFun Forums

[andrey]

Hi. I wanted to share my major projects:

EFI ECU
http://thedotcommune.com/oepec/ucsc.html
A programmable fuel injection control unit (ECU) for gasoline engines. Based on an Atmel mega128 microcontroller.

Function Generator
http://thedotcommune.com/function.html
This is the one I'm starting to work on now (there's just a simple block diagram up on the web). It will use an MCU interfaced with a DDS engine.

[upand_at_them]

Nice EFI ECU project. Makes me want to build an interface for my OE one so that I can see what's all going on (and figure out my idle problem).

Mike

[andrey]

If you have a 'newer' car with OBD-II (and to a lesser extent OBD-I) you can just connect to the plug under your dash and see all the stuff the ECU has to legally provide (MAP, IAT, injector duty cycle, etc). I like messing with older cars though.

If you're going to build a data capture for your (fuel injected) car, I would recommend that Freescale MAP sensor we used (MPX4115) for measuring manifold pressure via A/D and the ignition pulse circuit that we used for now (basically the one MegaSquirt uses) works well enough if you put the right filter caps on the input and output and then run the signal into an input capture pin on your MCU.

[upand_at_them]

It's an older car (no OBD), a 1991 VW Golf. I was thinking about grabbing all the signals at the connector to the car's ECU, using op-amps to prevent signal loss.

Mike

[jrcfg]

andrey,

Very interesting!! I am a long time "motorhead" and recent electronics geek. Thanks for sharing!

[riden]

I'll be watching with interest your progress on the function generator project!

What is the maximum frequency that you would like to generate? I've built a couple of function generators using software only synthesis. My top range using a PIC was about 65KHz and over 200KHz using a low end AVR chip. I found Luhan Monet's PIC project and the minidds project based on the AVR great starting points for a software only DDS.

When things quiet down around here, I want to take it to the next level and build an DDS with a top end of 100MHz plus using a DDS chip and microcontroller.

[andrey]

thanks! my goal is to build a 25MHz generator to beat my 12MHz wavetek but then to extend that design to use some of the monster 100MHz+ DDS engines from AD and see if I can get above the 50MHz range. I don't really have the background to deal with the RF issues involved in outputting clean signals at 100MHz and the like, but I will work with some people who know that stuff more and see what we can come up with. Here's an example of a very fast DDS project:

http://www.circuitcellar.com/library/pr ... /index.asp

Mike: I'm guessing your VW has a Bosch ECU (probably Motronic), and those are well-documented by Bosch in several of their books. Yeah, you can definitely tap into their signals with some care. Other VW owners will probably want to build copies of your project later

[riden]

my goal is to build a 25MHz generator to beat my 12MHz wavetek but then to extend that design to use some of the monster 100MHz+ DDS engines from AD and see if I can get above the 50MHz range. I don't really have the background to deal with the RF issues involved in outputting clean signals at 100MHz and the like, but I will work with some people who know that stuff more and see what we can come up with. Here's an example of a very fast DDS project:

http://www.circuitcellar.com/library/pr ... /index.asp

I was thinking of using the AD9852 in my amateur radio transceiver project. Unfortunately, that project is on the back burner for a number of reasons. I think that you will find that the RF issues at the frequency range you're working with to be managable if you have access to the expertise (which it seems that you do) and the right equipment to ensure your output is clean. The keys to success are decoupling from the power supply and a good low-pass filter. There are a few projects on the net along with the Circuit Cellar one to provide additional inspiration that it can be done!