If your MCU has only 1 UART and want to use it application which can switch between two UART source use this digital switch to select which UART you can connect to.
If your microcontroller has only one UART Serial port and you wish to interface with two devices each having one serial port then you are left with two options. First difficult option is to search for a microcontroller having dual uart. Second is a digital switch that we have made which can be used to switch same microcontroller UART pins to each serial device as required.
Many application which uses a MCU with GPS and GSM both can be used with this switch. Instead of GSM can be other RS232 device but we targeted to this GSM device and GSM device since this is the most common problem when trying to interface GSM and GPS to same microcontroller having single UART interface.
We have presented a digital switch which can be used to switch between two serial devices. We have designed it such that one serial port is RS232 level like GSM while other serial port is at TTL level, mostly GPS.
Microcontroller has access to a SEL pin which when made high or low switches between the two devices as per status of SEL pin.
When SEL pin is made high the MCU serial port gets connected to GPS(TTL) and while it is low the MCU port gets connected to GSM(RS232).
Connections to board are simple and will not need any major change in hardware or your software, except the MCU has to control a SEL digital input pin to decide which device it wants to connect to.
Currently we have one UART marked as GSM(RS232 level) and other is GPS(5V level). It can be any other device than GPS or GSM. Just that we have labeled it that way becauase using both GSM and GPS in MCU is most common use.