Hello PIC.ers,

Is there anyone out there in PICland who has -successfully- used the
MSSP in SPI mode to communicate with an Analog Devices AD7715 adc?

Tony Kubek has a note in the PIC archives about talking MSSP>SPI to the
related AD7730. His source code looks nice & well encapsulated but
unfortunately he does not elaborate on the AD_SEND_BYTE routine he
invokes to do both a byte write & read together.
(Tony, if you're listening...?)

The 7730 is a part I played with a while back but dropped it in favour
of the 7715 -it's cheaper & more available here.  IIRC the 7730 registers
are all byte-wide & this lends itself to MSSP SPI comms. where the port
wants to deal in 8bit words only.
The 7715 transmits its 16bit adc data as a complete word, with no choice
in the matter. It doesn't look like the SSPSTAT,BF flag can be setup to trip
on incoming 16bit words, only 8bit.

Given the above, *and*  :
(a)     I'm already communicating I2C on the *same* bus lines
        of the MSSP. (no problems there)
(b)    I Must watch my TMR0  ISR  Ps&Qs while I'm about all this.

erm...  would it be a collective opinion out there that I give up using
the MSSP SPI and rather go to bit-banging the SPI on some other
I/O pins?   It feels that way right now.


    best regards,   John


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