[Diy_efi] Data Logger CPU schematic and C for review

[Jean Belanger]

I've been following this thread with interest. Even though I don't need this
at the moment, I'm interested to see where it ends up and I might be able to
help at some point. Comments below.

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
> Behalf Of Adam Wade
> Sent: February 3, 2007 9:39 PM
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] Data Logger CPU schematic and C for review
> 
> --- "Steven P. Donegan" <steve at donegan.org> wrote:
> 
> > I am already doing RS-232 and LCD output logic in
> > the data logger - we can re-use that stuff with
> > the ARM...
> 
> I actually had a good idea formulate while reading
> this.
> 
> Why not offer source code to make the data logger
> optionally into a smart gauge "package"; you could use
> the separate processor in the data logger to handle
> measuring and displaying data from sensors etc., and
> doing data logging at the same time, and leave the
> processing power of the "main brain" for EFI-related
> tasks.  Would it be reasonable to send data for gauge
> functions through the I2C port?  I know some of them
> today runj much faster than the original standard, so
> it might be feasible to send a sensor "address" byte
> and a sensor reading perhaps two of three times a
> second.  Each sensor would have a data broadcast this
> often.  Does that sound reasonable?  Or you could even
> use the data logger as a "front end"; it inputs all
> your sensor data and then sends it out over the I2C to
> other interested parties, and you don't connect any
> sensors at all directly to the MCU.  And then you
> could have full display and control (perhaps useful
> when debugging, and def. useful when tuning) on the
> dash, while having the actual ECU under the bonnet.
> 

I think this is a good idea but this a case where a CAN bus would be of use.
Also, you would still need to connect any crank and cam sensor directly to
the MCU, of course. And unless the communications between the MCU and the
data logger can be kept well synchronized and/or very fast, you may want to
either connect sensors such as MAP, MAF, and TPS to the MCU or keep track of
their rate of change on the data logger and transmit that to the MCU to
handle acceleration/deceleration fuel and spark changes.

What would also be interesting would be the ability to directly drive analog
gauges. Since a lot of people lose some or all of the dash gauges when going
to a non-OEM MCU, it would be nice to be able to restore this functionality.
I don't know exactly how this would be done and it certainly is dependent on
the vehicle but some type of PWM or stepper motor controller would cover
some cases.

Regards,
Jean


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