I'd like to ask you for a little help here. I'm running FreeBSD 10.2 on a headless homeserver (ASRock Q1900-ITX MB with Intel J1900 CPU).
I'm trying to build a Remote Access Card using a Raspberry Pi, which should act as a terminal server enabling me to connect to the homeserver using serial console in case the network adapter is down or if I need to debug the boot process.
The RPi GPIO 3v3, GND, txd and rxd pins are connected to this module http://www.aliexpress.com/item/RS232-to ... 68742.html and then directly to a COM port bracket on the server.
In my lab environment I have tested the RPi connection with baud 115200 to a Mikrotik RouterBoard RB433AH successfully.
The problem is when I connect the RPi to the FreeBSD server, it seems like there are some characters beeing sent out of the serial port, which do interrupt the booting process several times (first is the BootLoader menu, I have to disconnect the serial connection and use a keyboard physically attached to the server to select the correct menu item and continue the boot process), then later during the boot process it hangs, until I disconnect the serial connection physically again.
Once I connect the serial port to a running system and open Minicom, I can see the login prompt but it's impossible to login because the user and password are filled with a lot of random characters automatically. Every key press on my end generates a new set of weird characters.
Let me remind that I checked the baudrate, parity and terminal type to match between FreeBSD and my Raspbian configuration, I tried different combinations but didn't manage to find a working one.
Nothing like this happens with the USB/Serial adapter, which works like expected (the interconnection is done via a NULL Modem cable).:
I doublechecked that the raspbian has turned off sending kernel messages to /dev/ttyAMA0 (used raspi-config to turn the console off).
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[404179.375842] usb 1-1.3: new full-speed USB device number 5 using dwc_otg [404179.478210] usb 1-1.3: New USB device found, idVendor=067b, idProduct=2303 [404179.478249] usb 1-1.3: New USB device strings: Mfr=0, Product=0, SerialNumber=0 [404179.539139] usbcore: registered new interface driver usbserial [404179.539316] usbcore: registered new interface driver usbserial_generic [404179.539474] usbserial: USB Serial support registered for generic [404179.543708] usbcore: registered new interface driver pl2303 [404179.543886] usbserial: USB Serial support registered for pl2303 [404179.544029] pl2303 1-1.3:1.0: pl2303 converter detected [404179.571090] usb 1-1.3: pl2303 converter now attached to ttyUSB0 root@raspberrypi:~# stty -a < /dev/ttyUSB0 speed 9600 baud; rows 0; columns 0; line = 0; intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0; -parenb -parodd -cmspar cs8 hupcl -cstopb cread clocal -crtscts -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl ixon -ixoff -iuclc -ixany -imaxbel -iutf8 opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke
Strange thing is, that if connecting the RPi to a router (Mikrotik RB433AH), everything works as expected out-of-the-box.