RS-232 driver for GPIO

Wed May 15 13:48:24 UTC 2013

Thank-you!

On Wed, May 15, 2013 at 7:46 AM, Warner Losh <imp at bsdimp.com> wrote:

>
> On May 15, 2013, at 9:40 AM, Tom Everett wrote:
>
> > ok, just one further question.  It was basically guess work that enabled
> me
> > to decypher that /dev/ttyu0 (sio0) was bound to uart0.  I presume there
> > must be some simple way from the command line to query the OS and find
> out
> > which hardware devices are bound to which /dev/ entries?
>
> The unit numbers generally match the alias names in the FDT.
>
> However, we don't note what the names for the nodes we're attaching to on
> FDT systems.  We really should, but we don't...
>
> Warner
>
>
> > On Wed, May 15, 2013 at 3:29 AM, Aleksandr Rybalko <ray at freebsd.org>
> wrote:
> >
> >> On Tue, 14 May 2013 20:24:42 -0600
> >> Tom Everett <tom at khubla.com> wrote:
> >>
> >>> Did you mean 14 &15, or 14 & 16?
> >> Yeah, right.
> >>
> >>
> >>> ok so given this, I've done some reading.  I'm by no means a FreeBSD
> >>> expert, so forgive me if I'm completely wrong.  I see this in the FDT:
> >>>
> >>> /* UART0 */
> >>> pins_uart0_a: uart0_a {
> >>>      broadcom,pins = <14>, <15>;
> >>>      broadcom,function = "ALT0";
> >>> };
> >>
> >> If you satisfied by single UART, you no need change that.
> >>
> >>
> >>>
> >>>
> >>> and this:
> >>>
> >>> chosen {
> >>>              bootargs = "";                  /* Set by VideoCore */
> >>>              stdin = "uart0";
> >>>              stdout = "uart0";
> >>>      };
> >>>
> >>
> >> But that stdin and stdout direct kernel console messages to air by your
> >> xbee :)
> >> So you need comment it or set different in/out device.
> >>
> >>
> >>>
> >>> So I interpret that to mean that uart0 is bound to pins 14, 15, and
> >>> furthermore that the serial device bound to uart0 is bound to stdin and
> >>> stdout.  In my /dev/ I see:
> >>>
> >>> crw-------   1 root  wheel     0x1f Apr 27 13:42 ttyu0
> >>> crw-------   1 root  wheel     0x20 Apr 27 21:42 ttyu0.init
> >>> crw-------   1 root  wheel     0x21 Apr 27 21:42 ttyu0.lock
> >>> crw-rw----   1 uucp  dialer    0x22 Apr 27 21:42 cuau0
> >>> crw-rw----   1 uucp  dialer    0x23 Apr 27 21:42 cuau0.init
> >>> crw-rw----   1 uucp  dialer    0x24 Apr 27 21:42 cuau0.lock
> >>>
> >>> So, that is telling me that sio0 is bound to uart0, which is a serial
> >>> console?
> >>
> >> Yep.
> >>
> >>>
> >>> If so, that means that I could use pins 14 & 15 for rs-232, but I would
> >>> have to chose b/t using those pins to talk to another device (xbee),
> or a
> >>> serial console?
> >>
> >> if you will disconnect serial console you will have to choose between
> >> control over network (SSH/telnet/etc) or graphic console (Display with
> >> HDMI + USB keyboard).
> >>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On Tue, May 14, 2013 at 5:17 PM, Aleksandr Rybalko <ray at freebsd.org>
> >> wrote:
> >>>
> >>>> On Tue, 14 May 2013 12:20:08 -0600
> >>>> Tom Everett <tom at khubla.com> wrote:
> >>>>
> >>>>> ok so the FDT definition would have to be added here?
> >>>>>
> >>>>>
> >>>>
> >>
> http://svnweb.freebsd.org/base/head/sys/boot/fdt/dts/bcm2835-rpi-b.dts?view=markup
> >>>>>
> >>>>
> >>>> Yeah, right.
> >>>>
> >>>> But I have bad news. Both UARTs can be connected to pairs(tx+rx)
> 14+16,
> >>>> 32+33, 40+41 and both UARTs can be connected to any of this pins.
> >>>> But only 14, 16 and 40(PWM0) wired to ext.pin.
> >>>>
> >>>>>
> >>>>>
> >>>>> On Tue, May 14, 2013 at 10:24 AM, Aleksandr Rybalko <ray at freebsd.org
> >>>
> >>>>> wrote:
> >>>>>
> >>>>>> On Tue, 14 May 2013 09:06:44 -0700
> >>>>>> Adrian Chadd <adrian at freebsd.org> wrote:
> >>>>>>
> >>>>>>> ... the r-pi actually has an RS232 port exposed via GPIO. It's
> >>>>>>> only 3.3v but it's there.
> >>>>>>>
> >>>>>>> Someone just needs to write up an SIO driver for it and then put
> >>>>>>> the GPIO pins in question into RS232 "mode".
> >>>>>>
> >>>>>> we have it already :) (console works on uart)
> >>>>>> only FDT definition is required.
> >>>>>> And maybe some fixes for boudrate setting and/or format setup
> >>>>>> (bits/parity/stop bits/etc)
> >>>>>>
> >>>>>>>
> >>>>>>> Yay multi-function GPIO pins!
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> adrian
> >>>>>>>
> >>>>>>>
> >>>>>>> On 14 May 2013 08:58, Tom Everett <tom at khubla.com> wrote:
> >>>>>>>> Good morning ARM mailing list.
> >>>>>>>>
> >>>>>>>> I've been running FreeBSD on my Pi, and I've now got two XBee
> >>>>>>>> Pros which I hope to connect.  XBee's communicate over RS-232.
> >>>>>>>>
> >>>>>>>> https://www.sparkfun.com/products/8742
> >>>>>>>>
> >>>>>>>> I see from the source tree that it was possible to attach the
> >>>>>>>> iic driver to GPIO pins in software:
> >>>>>>>>
> >>>>>>>>
> >>>>
> http://svnweb.freebsd.org/base/head/sys/dev/gpio/gpioiic.c?view=markup
> >>>>>>>>
> >>>>>>>> I'm wondering, it is possible to connect the FreeBSD serial
> >>>>>>>> driver for RS-2332 to GPIO in a similar way to how iic was
> >>>>>>>> connected?
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> --
> >>>>>>>> A better world shall emerge based on faith and understanding  -
> >>>>>>>> Douglas MacArthur
> >>>>>>>> _______________________________________________
> >>>>>>>> freebsd-arm at freebsd.org mailing list
> >>>>>>>> http://lists.freebsd.org/mailman/listinfo/freebsd-arm
> >>>>>>>> To unsubscribe, send any mail to
> >>>>>>>> "freebsd-arm-unsubscribe at freebsd.org"
> >>>>>>> _______________________________________________
> >>>>>>> freebsd-arm at freebsd.org mailing list
> >>>>>>> http://lists.freebsd.org/mailman/listinfo/freebsd-arm
> >>>>>>> To unsubscribe, send any mail to
> >>>>>>> "freebsd-arm-unsubscribe at freebsd.org"
> >>>>>>
> >>>>>>
> >>>>>> --
> >>>>>> Aleksandr Rybalko <ray at freebsd.org>
> >>>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> --
> >>>>> A better world shall emerge based on faith and understanding  -
> >>>>> Douglas MacArthur
> >>>>
> >>>>
> >>>> --
> >>>> Aleksandr Rybalko <ray at freebsd.org>
> >>>>
> >>>
> >>>
> >>>
> >>> --
> >>> A better world shall emerge based on faith and understanding  - Douglas
> >>> MacArthur
> >>
> >> Good luck! And let us know how things is going :)
> >>
> >> WBW
> >> --
> >> Aleksandr Rybalko <ray at freebsd.org>
> >>
> >
> >
> >
> > --
> > A better world shall emerge based on faith and understanding  - Douglas
> > MacArthur
> > _______________________________________________
> > freebsd-arm at freebsd.org mailing list
> > http://lists.freebsd.org/mailman/listinfo/freebsd-arm
> > To unsubscribe, send any mail to "freebsd-arm-unsubscribe at freebsd.org"
>
>

-- 
A better world shall emerge based on faith and understanding  - Douglas
MacArthur