Note that the HCI UART only supports the programming of the part, nothing more, regardless of if it is in programming or application mode. You can use the PUART or SPIFFY2 (secon, lower speed SPI port) for data transfers.
If a PC is on the other end, would a USB to Serial cable be an option, or does the UART switching logic need to reside on the custom board?
I'm not sure if any of the other customer on the forum have experience using an analog mux with the two UARTs.
Thanks for clarifying the operation of the HCI UART.
SPIFFY2 is going to be used for Flash memory, so I do need to use the PUART.
We need to have the USB connector on the board, so I am going to go down the route of mux'ing the HCI UART and PUART. The HCI UART will only be used during debug and factory programming. The end user, our customers, will never use it.
Would you mind glancing over my GPIO assignments to make sure I've followed all the rules?
Push Button GPIO Inputs
GPIOs Used in Power Circuitry
P12 Sensor Interrupt
Unfortunately, we have not tried to use an analog mux internally to seperate the two UARTs and the associated USB to serial conversion signal paths, so we will not be able to provide much guidance in this area.
Note that we do use a different USB to Serial device from Silicon Labs on the WICED Sense product (uses a 20737S module). We selected that device for WICED Sense because of the size.
I believe there are links to the device drivers for that device, along with the design files here in the WICED Sense Table of Contents
Taking a look at your pin configuration, it seems there is a problem with your SPIFFY2 SPI_CS pin. According to WICED Smart Hardware Interfaces , using P28 for the CS line is contraindicated. This shouldn't be too big of an issue, it can easily be swapped with another.
All other pins look good--no double-bonded issues, ADC is allowed, etc.
Thanks very much for checking the pins over. I'm intending to use SPIFFY2 in master mode for external flash storage to log data. In master mode, I was under the impression that any pin could be used for CS. I can't see anything about P28 not being allowed. Can you confirm?? PCB layout will finish this week, so this might be a timely catch!
My apologies, I assumed slave operation. There shouldn't be any problem using p28 as CS in the master role given that it, then, utilizes the generic GPIO driver API. Your pin configuration should be good to go.