Why not use a Raspberry Pi populated with several USB to console adaptors, there are USB console cables with up to four serial ports per connection which would result in 16 console ports per Pi.
The RPi has a serial port on which Linux can present a console. It's just a matter of converting the 3v3 RX/TX signal to some 12V RS-232 level. Plenty of devices or instructions out there.
> I wonder how much effort it would take to connect it to a Raspberry Pi.
Should be quite easy. You'll need a USB-serial adapter for the Pi, and a cable with a 9-pin serial adapter on one end and a 25-pin on the other.
Now, the way my luck works, it usually turns out that my random assortment of serial cables means I end up with the USB converter, a null modem adapter, the serial cable, and a 25-pin gender-bender just to get all the wires in the right order and fitting into the ports properly :)
I'm glad projects like this exist, but I'm too lazy and more than happy to have a Pi provide a serial console and a hardware reset via GPIO over IPv6 for colocated hardware. It's much simpler ;)
Exactly. A low end micro-controller would do the trick but a Raspberry Pi is much more accessible - almost anyone can get one fairly quickly and if they themselves don't have the knowledge to do the setup they most likely know someone who can help.
Sure, I would not expect to do any advanced IO. But right, probably there is no serial console really close to the CPU either, this is not a Raspberry PI. No idea what signals could be used for that.
Page tables I am not sure either. Could you still do it like in Linux 1.0? No idea what things looked like then, but I assume much less dedicated hardware support.
For stuff like this (connecting to a router) you really want to have serial adapters. Because it may or may not work, and if it doesn’t work, a bus pirate or raspberry pi pico has a lot more variables to troubleshoot.
I'd love to see more details on that. The RPi is the easy choice for putting together a DIY system at home, but finding good and affordable remote I/O modules to run the show has not been that straightforward.
Sure, you can hook up a low power serial transmitter to a Raspberry Pi's UART and have a text only console to operate over. But you are pretty much limited to text only and very slow file transer over a serial transmission like Kermit or Xmodem. You'll hate it for the type of computing you're used to. If you want a graphical remote desktop you are better off setting up a WiFi router/WLAN and connecting through a remote desktop connection. This will consume much more battery life, but I power a WiFi router with an RC LiPo battery and a voltage regulator and it lasts for several hours (but you certainly aren't getting days of battery life).
A Raspberry Pi is a popular emulation platform. There's essentially zero latency to read a GPIO pin. Even on macOS or Windows 10 platforms, one way serial-to-USB latency seems to be less than a millisecond.
Sure, but to what end? You've got 4 RS-232 devices, plus the Pi's onboard TTL serial console, and the VDU console as well. A TU-58, a papertape reader and punch, a plotter...?
Maybe you should pay to have built a batch of a thousand custom boards that are similar to, but not exactly the same as, the standard Raspberry Pi, so that they have a proper serial port etc.
You could also consider putting more than one ARM computer on each board (at which point maybe you want fewer than a thousand boards) and building an ethernet switch into that board, etc, and maybe you could even hardwire all the serial lines within the board, etc.
You can also get some game controllers and RetroPie and turn your Raspberry Pi into a sweet little gaming machine. I have every NES, SNES, Genesis, and N64 game ever made I think. Plus it plays every video format (tends to struggle with 4k video outputs... I don't have a 4K TV so I just re-downloaded the video after I saw the issue).
I would be interested in trying this... I'll be able to move mikrotik winbox over to my raspberry pi, which also acts as a serial console for my other arm computers.
> Anyone has experience making Raspberry Pi talking with server via RS232 serial interface?
I have:
- two Dell R710
- Raspberry Pi 3
- Raspberry Pi 4
- Several x86 machines
- StarTech.com USB to RS232 DB9 serial adapter [0]
- RS232 serial header adapter [1]
- DB9 cable [2]
The StarTech.com USB adapter seems to work well. I haven't had any trouble with it whatsoever.
I will say that I'm very unimpressed with serial interfaces in general but especially of Dell's BIOS output. Sure, they're aged... but serial is aged way older. Dell's firmware would often write to parts of the 80x24 screen which were already displaying something else and make it practically impossible to read what's going on. It seemed to especially occur when starting different sections of hardware. When the Dell firmware would start up, it would fill the interface with a text-display showing status and what's about to load. It would offer "press key to configure". When it goes to load drivers for netboot/disk/etc, it wouldn't clear the screen. Netboot would write its output on top of the "press key to configure" interface. Then drivers for the disk would write on top of _that_. Further, the configuration interface would sometimes wrap some of the fields to the next line and garble that line. And finally, the interface simply _didn't work at all_ if it wasn't at 9600baud. So input/output slow af. And the text would all be garbled if the serial bit rate were misconfigured with regards to 7/8 data/parity or check bits or etc (but that's to be expected). The problems with Dell's BIOS output to serial are difficult enough to work with that I would not try to use it to try to debug it outside of academic exercise. My time's worth more than that.
On the other hand, I have used it work with the bootloader (grub) before the kernel has loaded. I successfully used the serial interface to diagnose and repair a driver problem with a video card on an desktop that I had. I had a straight DB9 cable connected to a pair of motherboards who had serial interface headers. I'd connected a header adapter and a straight DB9 cable and encountered a lot of the same problems. That was a fun, albeit trying, experience because it involved a lot of reboot cycles which are quite time consuming. There were still a lot of similar problems with regards to overwriting parts of the interface that hadn't been cleared but they weren't nearly as numerous as with Dell's BIOS output.
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