Lpc2000

At 05:06 PM 4/8/05 +0100, dasbento@... wrote:
>I'm using an AD (ADS8325, texas instruments) and i want to comunicate
>with SPI. But i don't know how. The ADS8325 not have an internal clock
>. Therefore, it is necessary to use the SPI clock to make the conversions.
>Any solution to my problem?

It depends on how it works

Option 1 - The device only works when connected.  IE the select line must 
be held low during conversion.  In that case the A/D would presumably have 
a period where dummy bytes were clocked in to perform the conversion.  I 
would expect it to be documented that way, something like send 1 byte 
configuration followed by two dummy bytes for conversion, On the third 
dummy byte the actual converted data is clocked out.

Option 2 - The device clocks data in/out during the period the select is 
low but requires a continuing clock when select is high to actually perform 
the conversion.  In that case you could select the device as normal when 
setting up and reading.  Then deselect it and send out dummy bytes during 
the period it is deselected.  In any case you will be sending & receiving 
data while the clock is running.

Robert

" 'Freedom' has no meaning of itself.  There are always restrictions,   be 
they legal, genetic, or physical.  If you don't believe me, try to chew a 
radio signal. "  -- Kelvin Throop, III
http://www.aeolusdevelopment.com/