(Q) Input-Stage Question

[drachenminister]

Your are using a 74LS04 in the Input-Stages for DATA_IN, CLK_IN and ATN_IN and Level-Shifting via BSS138s and 10K resistors.

Would it be possible to use something like a 74HC4049 Hex inverting HIGH-to-LOW level shifter running off of 3.3v instead?

Or is there a problem with it beeing push-pull and not open collector?

Also, as it should be possible to only invert the signals once (ore use the non inverting 74HC4050) one could make room for RESET_IN as well an get rid of the BSS138s and 10K resitors all together.

But then there is a second pull-up resistor between the two inverters on the RESET_IN which baffels me.

lg
Martin Schneider