Use MEZZ_IO8 to MEZZ_IO11 to drive RF switches

[jordens]

Use MEZZ_IO8 to MEZZ_IO11 to drive Almazny RF switches.

Choose polarity, pull up/down, and OR/NOR/AND logic with shift register OutputOff such that:

1. if MEZZ_IO are not driven the behavior is unchanged w.r.t. now
2. if MEZZ_IO are deasserted the behavior is unchanged w.r.t. now
3. if MEZZ_IO is asserted the output is on

[gkasprow]

we can use OEpin of the register and another HCT244 chip that activates once shift register is not driven

[jordens]

Not a simple AND gate with pull-up on the MEZZ_IO input?

[gkasprow]

2 chips vs one chip and avoids confusion while driving from both sources

[jordens]

A quad AND gate is just one additional chip for all four channels, right? Changing the functionality of the OE signal is breaking. Using it would also prevent changing attenuation with RF on.

[gkasprow]

there are more than 4 signals. We can also use one IO to switch between register and straight IO

[jordens]

I count four OutputOff signals, one for each channel.

[gkasprow]

Ok, no atenuators.