[Diy_efi] EEPROM based efi compter, DIY style

[Curtis Richards]

Hi Ben,

What you are outlining sounds like a simplified version of Megasquirt.  
Since Megasqurt has been built by many people for many different 
vehicles and has Megastim and  Megatune software available for debugging 
and tuning the EFI aren't you 'reinventing the wheel'?  I looked at 
using one of the $20 TI  eZ430-F2013 ( complete system in a USB thumb 
drive with development software included ) for my !946 Jeep in order to 
be able to take the ECU with me and stop thieves from hot wiring it.  
Designing a board, writing the code and then writing a version of 
Megatune for the new system would be a LOT of work.  Especially when you 
consider that you can buy an assembles Megasquirt on eBay for a few 
hundred dollars:

http://cgi.ebay.com/ebaymotors/Megasquirt-v2-2-MS-engine-fuel-management-EFI-ECU_W0QQcmdZViewItemQQcategoryZ33553QQihZ004QQitemZ140065205754QQrdZ1QQsspagenameZWDVW

Curt

> Hi people.
>
> Just another of my less crazy ideas, I was wondering what it would 
> take to build a computer that can make a pulsewidth output based 
> primarily on a voltage (ie air flow meter).
>
> The idea would be to have four or five tables:
> 1: Air-flow/Pulsewidth (with pulsewidth the output)
> 2: TPS/RPM (pulsewidth output, overrides table one while rpm AND 
> throttle position are in range)
> 3: TPS change/Time (pulsewidth output, added to table one/two)
> 4: Temperature/Pulsewidth multiplier (simple warmup strategy, or a 
> master rich/lean knob)
> 5: O2/Pulsewidth multiplier (simple closed loop under certain TPS and 
> temp conditions)
>
> I can see this being a simple computer for converting naturally 
> aspirated engines to single point efi, with a minimum of wiring 
> required, primarily for economy.
>
> so how would you go about building something that can do this? My 
> electronics ability is limited to assembling kits and understanding 
> how simple components (transistors, capacitors, diodes etc) work, 
> along with limited BASIC programming. My main interest is in how to 
> program the EEPROM chip, and how to get the inputs to the correct 
> format (ie frequency is easy enough to do, but converting a voltage 
> into a digital signal is something I know nothing about). I am 
> presuming that an EEPROM chip can make a pulsewidth output directly 
> (with the aid of a transistor of course), is this correct?
>
> thanks
> Ben

-- 

Curtis W Richards

--
"I would rather be exposed to the inconveniences attending
too much liberty than those attending too small a degree of it." 

--Thomas Jefferson