I’m using a 74hc595 as part of adding a high speed spi input to an old-school micro that only has parallel input. My MISO is the 74595 serial input and the parallel outputs are gated onto the data bus with the /OE input.
looking at the 74595 data sheet here http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf the logic diagram shows that /OE is separate from the shifting and storage register functions but the transition diagram shows the shift register clocking into the storage register only when output is enabled. I’m not sure whether this is just a consequence of how the part is usually used or an actual restriction. Has anybody used the 595 in a similar way?
The logic and transition diagrams are attached.