If you are using a USB to RS-232 interface, then you can have problems. RS-232 is +/- 6 to 12 Volts interface. -6 to -12 V Negative = Logic 1, +6 to +12 V Positive = Logic 0. 0 Volts is undefined.
The Beagle bone debug connector is 3.3V TTL or CMOS serial interface. 0V => Logic 0, +3.3V => Logic 1. So, no surprise you are seeing garble. You need a USB to serial 3.3V interface to talk/listen to the debug interface on the BBB. --- Graham == On Thursday, May 5, 2016 at 2:04:33 AM UTC-5, William Hermans wrote: > > Just as an added aside. When the output from the serial debug cable gets > garbled. I do not think this is a problem with the beaglebone hardware. > Matter of fact I'm nearly certain. > > What seems to be happening is that line feeds are no longer recognized as > line feed, and are processes as tabs, or other random control characters. > Because text can back up, and over write other text sometimes. Perhaps a > call to fflush() needs to be made ? > > I wonder if Peter H has any insight on this behavior. > > On Wed, May 4, 2016 at 11:56 PM, William Hermans <[email protected] > <javascript:>> wrote: > >> *1. USB to RS-232 Converter >>> <http://www.amazon.in/RS-232-Serial-Converter-Cable-Technotech/dp/B017H1SD9E?tag=googinhydr18418-21&tag=googinkenshoo-21&ascsubtag=058e6ce6-5e13-4457-bf0e-61473874f9b4> >>> and >>> connected DB9 connector pins GND,TX and RX with that of the BBB J1(cross >>> fashion - TX-RX and vice versa) connector. My settings are 115200 8N1 @ >>> /dev/ttyUSB0 .* >>> *I can see logs on minicom but they are all garbled.Are my Serial Port >>> Settings correct.* >>> >> >> I use screen, and have tried minicon, but do not like minicon automatic >> screen size. Anyway, sometimes, and I'm not sure how both screen and >> minicon show garbled output too. When this happens, I've used cat >> /dev/ttyUSB0, and the output looks fine. But after some time, having cat >> /dev/ttyUSB0 running during a reboot, will cause the board to not boot. >> >> william@eee-pc:~$ lsusb >> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub >> Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub >> Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub >> Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub >> Bus 001 Device 003: ID 13d3:5071 IMC Networks >> Bus 001 Device 006: ID 058f:6335 Alcor Micro Corp. SD/MMC Card Reader >> Bus 002 Device 003: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial >> Port >> >> Which is actually a PL2303HX, has worked great on Windows 8 pro, through >> puTTY, but sometimes does not work properly when connected USB side to a >> Linux host. >> >> On Wed, May 4, 2016 at 11:12 PM, Raul Piper <[email protected] >> <javascript:>> wrote: >> >>> Thanks for the Prompt response. >>> I dont have that cable i mentioned above right now. >>> But I tried the below two Hardware . >>> >>> 1. USB to RS-232 Converter >>> <http://www.amazon.in/RS-232-Serial-Converter-Cable-Technotech/dp/B017H1SD9E?tag=googinhydr18418-21&tag=googinkenshoo-21&ascsubtag=058e6ce6-5e13-4457-bf0e-61473874f9b4> >>> and >>> connected DB9 connector pins GND,TX and RX with that of the BBB J1(cross >>> fashion - TX-RX and vice versa) connector. My settings are 115200 8N1 @ >>> /dev/ttyUSB0 . >>> I can see logs on minicom but they are all garbled.Are my Serial Port >>> Settings correct. >>> >>> 2.Tin Flyswatter CAN 2 >>> <http://www.tincantools.com/JTAG/Flyswatter2.html> >>> Same settings and Hardware connections with it and getting the same >>> result. >>> >>> Or Do I need only the h.w I mentioned in my first post. >>> >>> I believe the 1 , 2 h/w already have TTL 3v3 converter inside them?isn >>> it? >>> On Thursday, May 5, 2016 at 10:25:15 AM UTC+5:30, RobertCNelson wrote: >>>> >>>> >>>> On May 4, 2016 11:50 PM, "Raul Piper" <[email protected]> wrote: >>>> > >>>> > HI, >>>> > I am new to this group.I am trying to boot a custom kernel which I >>>> have built using this link .I hard pressed the Button S2 while the board >>>> was booting from the MicroSD CARD (not the EMMC) but I see no display on >>>> HDMI connected TV and neither any LED is glowing except the Power >>>> LED(PWR).I want to see the boot logs and opened the minicom by connecting >>>> the USB cable to the BBB but can't see any boot logs on the minicom >>>> (@115200).Is it possible to get the boot logs using the USB cable or do I >>>> have to purchase >>>> >>>> No, is not possible.. That interface you are using is created by the >>>> kernel itself.. Way after it started booting... >>>> >>>> "Serial Debug cable : for this like Standard FTDI Cable or Adafruit 4 >>>> Pin Cable (PL2303) or (USB to serial adapter) TTL-232R-3V3 at Digi-Key. >>>> >>>> Correct, that's the cable you need.. 3.3v... >>>> >>>> Regards, >>>> >>> -- >>> For more options, visit http://beagleboard.org/discuss >>> --- >>> You received this message because you are subscribed to the Google >>> Groups "BeagleBoard" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected] <javascript:>. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/beagleboard/5bedc12d-b1db-41f5-a1e5-4afd46dd29ba%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/beagleboard/5bedc12d-b1db-41f5-a1e5-4afd46dd29ba%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/90857501-8978-447f-baec-d25400285a72%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
