The number of arduino mega serial port

Hello,

I'm planing a project that is using rfid to find location.
I find that using 2, then computer calculate angle for difference of time.
Beside, if i use more then 2 of it, I can find location of 2d or even 3d map.
However, my arduino mega doesn't have more than 3 serial port.
So, I'm wonder could I expand rx tx port? I want 8 port....

However, my arduino mega doesn't have more than 3 serial port.

Your Mega has 4 hardware serial ports - Serial, Serial1, Serial2, and Serial3.

4 IS more than 3.

So, I'm wonder could I expand rx tx port?

Mr. Google seems to think that serial port expanders exist.

do a web search for arduino serial port expander
you could use a software serial port
what are you communicating with? could you use some other communications technique?

When I was investigating extra serial ports a while back it seemed that the cheapest way to add extra ports would be by using Amega 328 chips connected to the master using SPI.

...R

I found this and then I know arduino pwm port is connected to this bord's input port(rx tx port).
I think this could be connected to communication port(rx tx)but it doesn't.
I want to know why does it possible?

dongjee33:
https://www.atlas-scientific.com/product_pages/components/port_expander.html
I found this and then I know arduino pwm port is connected to this bord's input port(rx tx port).
I think this could be connected to communication port(rx tx)but it doesn't.
I want to know why does it possible?

But, it does connect to communication port(rx tx). The other lines are for selecting the 1:8 ports.