home bbs files messages ]

Just a sample of the Echomail archive

<< oldest | < older | list | newer > | newest >> ]

 Message 21924 
 bp to All 
 Re: serial port signal path 
 29 Jan 26 12:30:01 
 
MSGID: <10le9pc$tuqa$1@dont-email.me> 76ecdfb1
REPLY: <697a97c5@news.ausics.net> 0371f769
PID: PyGate 1.5.6
TID: PyGate/Linux 1.5.6
CHRS: ASCII 1
TZUTC: 1100
REPLYADDR bp@www.zefox.net
REPLYTO 3:633/10 UUCP
Computer Nerd Kev  wrote:
> bp@www.zefox.net wrote:
>> Does anybody happen to know how data travels between gpio pins
>> 8 and 10 and the system console? In other words, what hardware
>> and maybe software facilitate the exchange? For example, the
>> internal ethernet adapter is connected to the CPU via USB. Is
>> something analogous for the system console?
> 
> I know with the BCM2835 (Pi 1 and Zero) both the UARTs (serial
> ports) are part of the SoC, as described in the peripherals
> documentation (often called the datasheet, though it's not really).
> They're "peripherals", but part of the chip so the signals connect
> directly - definitely no USB interface in-between. Other RPis
> _could_ be different but it's extremely unlikely because at least
> one UART peripheral is pretty essential, even just during product
> development.
> 
Ok, that largely answers my question. If the console is stand-alone
the mischief isn't related to some intermediate driver software.

>> I'm seeing what look like console failures on older-model Pi2s
>> (v1.1) and wondering if some accessory subsystem, (usb comes
>> to mind but I don't think that's it specifically) when running
>> FreeBSD-current.
> 
> Even though it's part of the same SoC as the CPU and other things,
> the UART is still something that can fail or be misconfigured even
> if there's nothing like USB in-between. Running a program/script
> that toggles the power light on/off (or another GPIO signal that
> you monitor) would indicate whether the CPU is still running when
> the serial console hangs.
> 
>> The machine stops without complaint or warning, does not answer
>> ping and has to be power cycled.
> 
> Since it doesn't respond to a ping either, that suggests that it's
> probably crashed completely.

That's my present supposition also. 

Thanks for writing!

bob prohaska


--- PyGate Linux v1.5.6
 * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)
SEEN-BY: 105/81 106/201 128/187 129/14 305 153/7715 154/110 218/700
SEEN-BY: 226/30 227/114 229/110 112 134 200 206 300 317 400 426 428
SEEN-BY: 229/470 616 664 700 705 266/512 291/111 292/854 320/219 322/757
SEEN-BY: 342/200 396/45 460/58 633/10 280 414 418 420 422 509 2744
SEEN-BY: 712/848 770/1 902/26 2320/105 5020/400 5075/35
PATH: 633/10 280 229/426


<< oldest | < older | list | newer > | newest >> ]

(c) 1994,  bbs@darkrealms.ca