Dual BIOS SPI with toggle driven switch

[Alex.]

Hello Guys, i am new here and i think this is right place for this post, if not please advice me where to put.

i have question for some very strange solution.
I would like to add 2 identical SPI chips (with different bios) on same board (which have only one 8pin pad for SPI chip) and to switch them between with one toggle switch 3 or 2 state (1on/2off/3on) or (1on/2on).
Toggle switch should be like 1m from device.

My plan is to put two pairs of 6x n-channel mosfet per SPI. and drive switch gates with 12v alw on over toggle switch.

So i have 8 pads on board. i would like to solder 2x wires from board pads to source of each n-channel mosfet and drain from mosfets to dedicated spi.

Here is schematic that i draw fast in paint just to get an idea how i wish to fix it.

My question is it which mosfet is good for this solution(if there is some fet that would work in this way) and is it posible to transfer dq1 dq 0 and clock without noise ?

I wish to say that wires from board pads over mosfets to the spi will not be longer then 7 - 8 cm max.

chips will contain normal and MODED bios which i wish to switch before booting. if there some logic IC which can be driven over one gate and switch betwen to wires please let me know how is best way to fix this.
THANKS !

[ala_borbe]

Re: Dual BIOS SPI with toggle driven switch

i think that all this is not needed... make a board on wich you can solder both eproms, then make dip switch or jumper to set power to one or another and rest of the legs/contacts solder together.. never tried it, but it should work

[Alex.]

Re: Dual BIOS SPI with toggle driven switch

i think that all this is not needed... make a board on wich you can solder both eproms, then make dip switch or jumper to set power to one or another and rest of the legs/contacts solder together.. never tried it, but it should work

Thank you for answer. I tried with only vcc (3.3v) switching and it's worked but reading from eeprom was not 100% correct. it seems that other pin/s from chip that is not powered by 3.3v change impedance (Z) and that make reading from powered chip incorect.
And toggle switch should be arround 1m from board with spi. So it's looks to me that best way is some voltage driven gate (not logic or any data) because on 1m it would lost any sync by spi communication.

[ala_borbe]

Re: Dual BIOS SPI with toggle driven switch

your cables should be as short as possible... to much resistance lowers your 3.3v power and thats why you cant read propertly