Shiftin with external Clock howto ?

[Charles Linquis]

There is probably a slick way of doing all of this with the standard PIC hardware, but maybe this is the time to get two cascaded 8-bit serial in / parallel out shift registers and use them.

But another possibility: Since you are trying to read what is sent to the DAC - There are quite a few PICs with 12 bit A/Ds. (18F8723 for one). You could just A/D the DACs output. The PIC will convert in about 25uSec, if you have a low source impedance (which you should with the DAC). 25uSec is fast enough to digitize audio.

[RFsolution]

Hi all

First of all thanks for the reply's

I'm measuring 28.2 uS periode for the clock going to the DAC7611

[Charles Linquis]

If you run an 18F at 40Mhz, you can decode that in software. If you don't need to do anything else at the same time, it is easy. But
if you have to read continuously while you are doing something else, then I would recommend making friends with someone who can write you an ISR in ASM.

[Charles Linquis]

I have been doing some timing. You can, indeed get into- and out of, an ASM interrupt in about 12 uSec (18F @ 40Mhz), so that is a viable solution. A PBP ISR takes about 25, so that wouldn't work.