Multiplex IC 5 inputs and 5 outputs custom?

StealthRT said:

Because i will be using a FTDI ft232r chip and the RX/TX lines will differ depending on what board is being used to program it using the FTDI.

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Notice that a straightforward solution doesn't exist. That means that every person managed to survive by solving the issue differently. It seems like your possible solutions are more difficult than the problem.

What I am looking to accomplish is taking this layout:


and connecting those pogo pins to the multiplex/demultiplexer/crossbar switch/cross point switch in order to allow for different pcb models that have different pin layouts in order to flash firmware to them using the FTDI.

Hopefully knowing that allows you to understand the overall design of what I am trying to do.

an fpga or cpld could do it. just mind the timing requirements bertween signal paths. go with a module rather than bare chip unless you know what you're doing. cross point chips are so big, rare and expensive that even fpgas/cplds are easier to get and use.

you could also just use a plug switchboard with headers and shunts (like old telephone switchboards) to manually modify the pinout. I would do this because everything else is super big and complicated relative to the task at hand.

Given the mix of possible signals for each pin, it might not be possible to achieve it with a single device. A regulator with a high-impedance disable mode can supply the 3.3 V, 5 V, or whatever else under program control, or be off. Separate from that, a high speed signal mux (again with a high impedance disable mode) can move the signals to the same pin.

ak

StealthRT said:

What I am looking to accomplish is taking this layout:


and connecting those pogo pins to the multiplex/demultiplexer/crossbar switch/cross point switch in order to allow for different pcb models that have different pin layouts in order to flash firmware to them using the FTDI.

Hopefully knowing that allows you to understand the overall design of what I am trying to do.

Click to expand...

I've programmed the ESP8266 from a breadboard. They are not finicky. Just rearrange your jumpers as needed depending on the device you want to program. Easy.

I have planned to sell this eventually so its easier for tinkers to flash the chip(s) without the need to solder first or the need of a breadboard.

StealthRT said:

I have planned to sell this eventually so its easier for tinkers to flash the chip(s) without the need to solder first or the need of a breadboard.

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It'll drive the price of the board up by a lot. Selling to hobbiests means no FPGAs, no CPLDs, and no actual crosspoint switch ICs because they are all expensive ICs and require expensive PCBs.

I'm with AK here... I think I'd aproach this using tri-state buffers between all inputs/outputs for the data and high-side switches (PNP or PMOS) to switch in the power - where needed - with the data buffers high-Z.
If you're supplying power to someone else's board, then you really don't have much control over how much it will draw.

As per #21, there are deffinately lots of solutions.

the signal pins won't be a problem, but power supplies are not something you want to switch using 4066's. if you check out various modules that will be programmed with your device, check for some kind of pattern with power and ground connections, maybe it can be done without having to switch the power supplies around... if you end up needing to switch supply rails around, maybe it could be done with MOSFET switches rather than some exotic xpoint switch chip. make a spreadsheet of the devices and pins, that will help spot any patterns in the pin assignments.