How to send FFFE (32bits) via SPI?

Forum 2005-2010 (read only) Hardware Interfacing
1

What is the best or efficient way to send 24 or 32 bits via SPI?
Since the ShiftOut function is only 8 bit, we can use
ShiftOut(Datapin, Clockpin, MSBFIRST, (value>>8))
ShiftOut(Datapin, Clockpin, MSBFIRST, value)
to send 16 bits, how would 24 or 32 bits work?
I would think a bit-bang routine might provide the answer, however, I am unable to produce the required code.
ANY assistance would be greatly appreciated.
Thank YOU!

2

ShiftOut(Datapin, Clockpin, MSBFIRST, (value>>16));
ShiftOut(Datapin, Clockpin, MSBFIRST, (value>>8) & 0xff);
ShiftOut(Datapin, Clockpin, MSBFIRST, (value) & 0xff);

for 24 bits, can you work out what 32 bits would look like?

3

Thank you sir for your quick response!
I thought it would be some type of ANDing routing with FF mask.
I will try this as soon as I am home.

Warm regards,
Doyle