Ubiquiti M radio
HamWAN Tampa uses the M3 and M5 radios for backhaul.
Serial port
J1 is serial port and takes a 4 pin .010 header. 115200, 8N1 is the port speed. Output is only at boot.
Top = pin1 Pin 1 = 3.3v Pin 2 = serial data RX (from PC to Radio) Pin 3 = Serial Data TX (from Radio to PC) Pin 4 = Ground
U-Boot 1.1.4.2-gd9d730c7 (Feb 14 2020 - 10:52:59) DRAM: 64 MB Flash: 8 MB PCIe WLAN Module found (#1). Net: eth0, eth1 Board: Ubiquiti Networks XM board (rev 1.0 e1c3) Hit any key to stop autoboot: 0 ## Booting image at 9f050000 ... Image Name: MIPS Ubiquiti Linux-2.6.32.71 Created: 2020-07-15 13:58:30 UTC Image Type: MIPS Linux Kernel Image (lzma compressed) Data Size: 1034643 Bytes = 1010.4 kB Load Address: 80002000 Entry Point: 80002000 Verifying Checksum ... OK Uncompressing Kernel Image ... OK Starting kernel ... Booting...
Reset Circuit
There is a reset circuit which can be activated via the Ethernet cable. This can be disabled in the firmware, however, this still is active at boot and can put the radio into a bootloader mode. This causes the radio to come up at 192.168.1.20 and expect firmware via TFTP.
This is activated by a >15v potential on the Ethernet data lines with respect to ground. As this is totally non-standard and violates the balanced nature of the Ethernet system, it's possible to have this happen due to leakage voltage across the Ethernet.
Removing D903 completely disables this. I move it aside and then use some lackor to secure it in the radio, just in case it's needed again.
Flemming Frandsen has a good description of the circuit on his page. Note that the part designations he uses are different than what's really on the board.
