A/B access switch to CF-card, please help

[domu]

Let's say that we have CF-card, and we have two devices that
need to have full R/W access to it, one device at the time.
Hence we would need a simple circuit that control access to
CF card either from device A or device B.

Note: dynamic switching is not needed. Switching can be done
at reset, ie. at the press of the button MCU simply memorizes
that another device should have granted access, and enables
access to that device after reset.

Please give me your thoughts how would you approach this
problem.

Any helpful answers much appreciated.

Thank you.

 

[alec_t]

Multiplexer IC, or transmission gates under micro control.

 

[domu]

Great answer!. Thank you very much.

I looked up transmission gates definition, and it seems like perfect
solution to the problem. I found on the Maxim site DS3690 IC which
seems like a good choice for this task. It features 26 A/B switched
parallel channels.


That leads me to another question - which lines of CF card would
need to be switched ? Would 26 channels be enough to handle data,
address, and control lines, or that would not be necessary to switch
all of them ?

My interest in hardware extends from coding side, so please excuse
me if I am asking a trivial questions.

 

[alec_t]

which lines of CF card would need to be switched ?

I'm not familiar with CF card pin-outs/protocols. Someone else may be able to help.

 

[domu]

I understand. Thank you again.

Based on available references for CF-card 16-bit transfers we need:

- 16 data lines
- 3 address lines (register pointer)
- 10 control lines

that is obviously 3 more than 26. The question: would it be safe to
leave address (or data) lines connected to both sides of the switch
at all time, and only switch the control, and maybe data lines ?