Date: Thu, 7 Feb 2019 02:10:19 -0600 From: Dustin Marquess <dmarquess@gmail.com> To: Brian Scott <bscott@bunyatech.com.au> Cc: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: Serial Port on RPi3 Message-ID: <CAJpsHY7trHxX2QDAnh--tE8UXnEAH0ZsQ2YZ2-Y0SppFYojPpA@mail.gmail.com> In-Reply-To: <75aa4f8f-1c93-0cc0-b3ed-0208c40098be@bunyatech.com.au> References: <75aa4f8f-1c93-0cc0-b3ed-0208c40098be@bunyatech.com.au>
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You're absolutely right about the PL011 speed change issue. I had the same exact issue (for the exact same reason too, GPS!) and gonzo told me to use init_uart_baud in my config.txt: https://lists.freebsd.org/pipermail/freebsd-arm/2017-January/015474.html I managed to get the older U-Boots to not spew on the UART at all. The newer ones seem to desperately want one and panic/die/etc if they can't find one. I spent hours on it and finally just gave up :(. -Dustin On Thu, Feb 7, 2019 at 12:17 AM Brian Scott <bscott@bunyatech.com.au> wrote: > > Hi, > > Has anyone had any success using the serial port on a Raspberry Pi 3 at > anything other than 115200? > > I'm trying to connect a GPS module to it (as most people do...) but am > having a lot of trouble. > > To give myself some diagnostics I have connected another machine up > using an adafruit cable and a terminal program. > > My first problem was u-boot. I have largely managed to get it out of the > way by setting the stdin, stdout and stderr environment variables to > usbkbd, vidconsole, and vidconsole (i.e. removing the serial option) but > it still insists on sending: > > MMC: mmc@7e300000: 1 > Loading Environment from FAT... OK > In: serial > Out: vidconsole > Err: vidconsole > > at 115200 baud before getting out of the way. No big deal because it > doesn't look like gps commands and it is being sent at much higher > speeds than I would expect the gps to understand anyway. > > The message on boot for the UART is: > > uart0: <PrimeCell UART (PL011)> mem 0x7e201000-0x7e201fff irq 24 on > simplebus0 > > If I send data to the uart (echo Hi >/dev/cuau0) it works but at 115200 > baud, not respecting the stty speed of 9600. Similarly, using cu (cu -l > cuau0 -s 9600), I can send data but at 115200, not the expected 9600 baud. > > I have done some experiments with enable_uart= in the config.txt as well > as overlays from the linux world (uart0.dtbo and uart1.dtbo). While I > can get FreeBSD to detect the Mini-UART with some combinations of > settings, either on it's own or with the PL011, I haven't been able to > get anything out of the mini-uart and only a single character out of the > PL011 (at 115200 baud despite other settings). > > My conclusions so far: > > * There is no working driver behind the detection of the mini-uart. > * There is no way to change the speed of the PL011 to anything other > than 115200 (maybe because u-boot sets it that way at startup - > haven't fiddled with those knobs yet). > > Am I missing something important somewhere? > > Cheers, > > Brian > > P.S. I'm running 12-RELEASE with no software changes. > > > _______________________________________________ > freebsd-arm@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-arm > To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org"
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