[Diy_efi] EFI system data

Kent Martin kentmartin at froggy.com.au
Wed Jul 24 13:19:56 GMT 2002


The MCU does have pwm output but I'm superimposing a 20Khz square on top of
the injector
on period. To do this I must have an interrupt at each toggle of the output
or use another timer to
stop the 20Khz timer. This would require two timers for each injector and
this is not desirable
as it has only 11 timers, and I need a few others as well. |A ballast
resistor I would have thought would
give a slower opening time and more non linearity of  volume with open time,
plus it's a bit low
tech for me.

Kent.

----- Original Message -----
From: <bill.shurvinton at nokia.com>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, July 24, 2002 8:37 PM
Subject: RE: [Diy_efi] EFI system data


www.bgsoflex.com/megasquirt.html

Chose an MCU with PWM outputs, much easier. OR use the tried and trusted
ballast resistor method. I have yet to see measured data to show that this
is any worse than a true peak and hold driver or PWM system. The inference
being that, for OEMs the circuitry of a P&H driver was cheaper than a bank
of big power resisitors.

Bill

-----Original Message-----
From: ext Kent Martin [mailto:kentmartin at froggy.com.au]
Sent: 24 July 2002 08:03
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] EFI system data


What's an MS style PWM?
I'm using a micro to generate the PWM.
I may run into trouble generating 10-15% duty because
of processor load, will 50% kill the injector.
Kent.
----- Original Message -----
From: <bill.shurvinton at nokia.com>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, July 23, 2002 10:39 PM
Subject: RE: [Diy_efi] EFI system data




-----Original Message-----
From: ext Bruce [mailto:nacelp at bright.net]
Sent: 23 July 1995 13:02
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] EFI system data



----- Original Message -----
From: "Kent Martin" <kentmartin at froggy.com.au>
<SNIP>

If you are using a MS style PWM to provide the hold current then start at
1Amp per injector, which is 10-15% duty cycle for a 2Ohm injector. Adjust
till it works. Once you are tuned in, it may be worth backing off a little
until you reach a minimum reliable hold current.

Bill

> What is the duty cycle required to keep the average injector open
(assuming
> a 20 Khz frequency)?

20KHz?  Your not goin find and injector to operate at that speed.
Bruce
>
> Kent.



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