![]() ![]() But it's pretty powerful when you need it.Īs you already know, I'm sure, the serial sections of these two devices are wired so that they are chained together. ![]() This 'double-buffering' allows the shifting process to be unbroken (continuous.) Whether or not that's desirable is another thing. It works either way.īut a reason for selecting such a nice, full-functioned chip like this one instead of, for example, the 74HC165, is that you can load the next 16-bit word to be shifted out while a current 16-bit word is still in the middle of being shifted out. Or, you can capture the MODx_STATUSy wires, wait a while, transfer them into the shift register and shift them out at a later time, delay still longer after that is done, and only capture the MODx_STATUSy wires when nothing else is going on. ![]() So you can change the data latch even when you are actively shifting out a prior value. This is because the data latch isn't the shift register. The above capture can take place at any time during the serial-shifting process for an earlier capture. (You cannot capture some of them at different times from others.) Obviously, that means all 16 MODx_STATUSy wires are captured, simultaneously. Since both parts are tied to this control line, the rising edge affects both of them at the same time. A rising edge here will take a snapshot of the 16 MODx_STATUSy wires (pins 1-7 and 15) and capture it into the data latch. The way it's arranged, pin 12 ( RCK on the schematic) of both parts are wired in parallel to the control line named BP_STRB1. And that's a nice-to-have in a part like this. You can latch the parallel input independently from what's actively going on with the shift register. ![]()
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