Sort of to do with EFI (more electronics)

[bohblesku]

Hi,
The following email is about A-D conversion of inputs from various
sensors. It's not really about EFI (sorry) but as some of
you may know the answer, I post it here :o)

I am in the process of making a digital data-logger which uses an 8051
(similar) with 6 channel A-D conversion on chip. All seems to be ok. I
have the LCD, a PIC 16C55 controller board interfacing to RS232 that all
works ok. Now, the quest is to interface it to the real world. In
researching this, I have decided to use 80C550 or 87C748. There is no
reqirement in the design to use a serial link, so they should be ok.
The questions I have are;
    The oil temperature, water temperature, oil pressure sensors use
what range of voltage? It is my understanding that they ground a "12V"
signal and the resulting current flow is used as the measure of sensor
range. Is this true for all the sensors?
If you know about A-D conversion, I am stuck at this point not being
able to interface the 8051 family A-D converter to the real world. ( I
am a computer engineer, I know a little about digital electronics, but
obviously lack quite a bit in this area )
    I found a great site www.8052.com that gives many details about the
chip, interfacing and programming. At the moment, everything to do with
the 8051 seems to be sorted out except for the Analogue part!

I would appreciate any help or suggestions, if you are interested in the
project, it is no top secret, so I would be pleased to share more
details with you.

Thanks in advance
Tim Freeburn