AnsweredAssumed Answered

Interaction between SPI and FLAGS?

Question asked by rkm on Oct 24, 2009
Latest reply on Oct 28, 2009 by DivyaS

I am using the SPI port in my program for the ADSP21369,

and I also use FLG0 through FLG3 for diagnostic output. I have

found that when I try to write to the FLAGS register close to

where I use SPI communications in my program, the processor can hang.

It says in the manual that if you disable the SPI port by setting

a bit in the PMCTL register, you can't use the FLAGS because

they are "synchronized to the clock." I must admit that I have

no idea what that means. I don't write to the PMCTL

register at all, although I do disable the SPI port at various times,

by writing zeros to the SPI control registers. But still there seems

to be a definite interaction between using SPI and changing flags

by writing to the FLAGS register, and as I mentioned it can

crash the program. Does anyone understand the nature of this

interaction? Is it documented anywhere? I really don't understand

the brief allusions to it in the Hardware Reference Manual and

the Programmers Reference manual.