Thank you for your explanation it helped a lot! i only have wo data lines that i need to control and they both run between 5-5.5V.
Hi Sarah,I don't understand from your explanation what you are doing, please post a schematic.These days use MOSFETs for everything. There has to be a really good reason to use a bjt.
If you are re-routing the TX and RX lines between devices, you could also consider an analog multiplexer chip. say the CD74HC4052. These are very cheap and quite easy to use.EditI've just noticed that @semtex9 had made a similar suggestion.
thank you, im trying to keep the cost to absolute minimum (even though my ics are quite expensive!) so id rather incorporate mosfets instead of a dedicated chip.
Your MOSFETs seem to just join Rx to Tx, I don't see what they are supposed to do. If you want to switch serial data then 6v6gt's suggestion is best. Serial does not require pull the up or pull down resistors.This might just be a personal thing but I hate join the dots schematics, the whole point is to show connections with lines, not have to find where things go by searching all over the schematic.
You have another alternative of using dip switches to re-route Tx and Rx.Here is an example of a somewhat similar design, actually it is connecting an Arduino Mega to an ESP8266 where the TX and RX have to swapped around to program the individual components. Schematic
well the design consists of 4 schematic pages and the header im using for that purpose is in another page! but i have attached the STN_TX and STN_RX to that header. this is my first time ever designing a board and im still trying to learn how to use the easyeda website. sorry if i caused any confusion.