I have a board that I would like to design and there are 11 devices that can only be spoken to via UART. I am restricted to a Microchip uC chip product range and I have found one with 5 UART ports. I have come up with a jumper based solution whereby the user, with making the connection via jumpers to the 5 available ports, can choose 5 of the 11 devices. I have been looking for a chip that will take either UART, SPI or I2C in and give me a few additional UART ports but I have come up short. Can anyone suggest a solution or a product that they may have come across?
It is not critical that all 11 devices are able to connect to the uC (that would be nice) but it is important that these devices are on the board for a modular product. However, I wish to make the product more user-friendly as the jumper based solution is a bit complicated at first glance or so I have been told.
EDIT
Okay sorry, I am not explaining the problem properly. With this method, you limit the user's options. Let say you link port a to device 1 and 2 and port b to device 3 and 4 and so on…
But what if the user would like to use device one and two? Then the product is limiting the user heavily. With 5 port options and 11 choices for devices, the binomial coefficient yields 462 combinations for the user to choose from. That is overkill, I am not looking for that level. But with the jumper based solution port a can connect to 9 of the devices while port b can connect to 7 of the devices, port c can connect to 8, port d can connect to 7 and port e can connect to 9. The number of mux switches needed to do this would be over the limit.
Is there another solution to giving the user the option to use (close to) any combination of the devices?
I have thought about using two uC with 5 UART port each to connect to 10 of the devices and then using a much smaller jumper based solution for the last device, but this solution is too complicated for production and is expensive.
Are there any Chips or concepts out there that will expand the UART control to 11 devices?
Best Answer
Use some UART-SPI bridge ICs, like:
You can have as many UARTs as you have spare GPIO pins to use as Chip-Select lines (or use a demux or decoder and you can have orders of magnitude more) - limited only by your UART baud rate vs the max speed you can run your SPI.