I am thinking of making a interface board between systems (for GPS and other arduinos etc) and am wondering whether you can have more than 2 serial ports in total?
Any ideas welcome.
The limitation on the number of software serial ports you can have is mainly determined by your programming skill. The simplest software serial implementation uses delays to achieve timing, which means you won't be able to do anything else while using one of the software ports. If instead of delays you get fancy and use timers and interrupts, you can use many software serial ports in parallel.
Or you can use a single hardware serial port and connect multiple devices to the same serial line, but then you'd need to come up with some protocol so devices on the line can know what data packets are meant for them and what data packets are not (and hence should be ignored). You'd also need to ensure that the various devices aren't trying to transmit at the same time or else your receptions will be garbage.
- Ben