SG-2220 PCIe and Serial port questions
I recently was digging through pfSense's settings on my SG-2220 and noticed that I could set up an NTP daemon using a serial connected GPS chip as a stratum 1 NTP server. I also noticed that I could select two serial ports in the drop down menu. I first did some googling but could not find any information on where the serial ports were or any additional info on using this feature on Netgate appliances.
I then proceeded to take the cover off my router to look for obvious headers but did not see anything labeled as a serial port. When I did this however, I noticed the PCIe/M.2 slot on the bottom along with the sim card slot on top.
Is there a header for a serial port populated or the space for one provided on the board? If there is, what is the interface, voltage level and protocol type?
Can I utilize a PCIe cell modem in the slot on the underside of the board and is there any documentation on how to set it up properly in pfSense?
Is there any good documentation on the physical hardware of the Netgate appliances? I don't want to have to buy a year of gold, just to ask one question. (my included year already expired).
No there isn't a header or unpopulated through-holes/pads for serial. I believe the only viable option would be a PCIe serial card in an m.2 form factor. I attempted to do the same on the SG 2440 which has mini PCIe, but the only product didn't appear to have FreeBSD support so I gave up.
Yes, you can add a cellular modem. Unfortunately, most of them don't support NDIS and get crap speeds unless they are connected directly to a machine running Windows. As for a guide, there don't appear to be many so you will have to do some googling and hope for the best. Personally, I'm waiting for generic android tether support. Granted this will probably result in a double nat (or worse) but it will be easy to setup once implemented.