McBSP or SPI to connect f2812 and DAC8554?

DAC8554 requires 24bits in one frame, 8 control bits and 16 data bits, and
its enable pin SYNC has to be valid during transmission. SPI data length is
only 16bits and I suppose its enble pin SPISTE is only valid for 16bits
(please correct me if I am wrong), so does that mean I can only use McBSP
to connect? If SPI can be used to connect, how to make SPISTE be valid for
at least 16bits of data transmission?

>DAC8554 requires 24bits in one frame, 8 control bits and 16 data bits,
and
>its enable pin SYNC has to be valid during transmission. SPI data length
is
>only 16bits and I suppose its enble pin SPISTE is only valid for 16bits
>(please correct me if I am wrong), so does that mean I can only use
McBSP
>to connect? If SPI can be used to connect, how to make SPISTE be valid
for
>at least 16bits of data transmission?
>
My mistake in last post. The last sentence should be "if SPI can be used
to connect, how to make SPISTE be valid for at least 24bits (not 16bits) of
data transmission?"