Dear Robert, Sorry to necro bump the issue.
I'm trying to enable RTS for UART4 on the Beaglebone Black, where uname -r informs me that I'm running 4.4.30-ti-r64. I build the dtbo correctly from UART4-RS485-00A0.dts. After correctly implementing the dtb (echo BB-UART4-RS485 > /sys/devices/platform/bone_capemgr/slots, as well as attempting to enable through /boot/uEnv.txt), the RTS functionality is still not enabled: cat /proc/tty/driver/serial: 0: uart:8250 mmio:0x44E09000 irq:158 tx:407 rx:0 RTS|CTS|DTR|DSR 1: uart:unknown port:00000000 irq:0 2: uart:unknown port:00000000 irq:0 3: uart:unknown port:00000000 irq:0 4: uart:8250 mmio:0x481A8000 irq:184 tx:0 rx:0 CTS|DSR 5: uart:unknown port:00000000 irq:0 showing the RTS for UART4 is not enabled. Furthermore, cat /sys/devices/platform/bone_capemgr/slots: 0: PF---- -1 1: PF---- -1 2: PF---- -1 3: PF---- -1 4: P-O-L- 0 Override Board Name,00A0,Override Manuf,BB-UART4-RS485 Showing that the overlay is functioning. The UART itself is fully functional, but the RTS pin P9_27 (or any one that I change it to) is unaffected by UART transmissions of any kind through UART4 (/dev/ttyO4), as checked with an oscilliscope. After researching for a fair amount of time, I haven't seen an update relevant to this thread concerning the 8250 drivers vs the OMAP drivers for RTS not working, and as of yet have no idea if there has been a recent patch, or if I should revert to disabling 8250 and enabling OMAP. If this is the case, could you please provide some insight into how this is done on the recent kernel 4.4.30? And if a later kernel is available that includes the correct patches, could you please enlighten me as to how to get that to work, as you seem to be the most informed person concerning all things Beaglebone. Any of your guidance would be greatly appreciated. Kindest regards, Matthew Bezuidenhout On Friday, February 12, 2016 at 5:42:24 PM UTC+2, RobertCNelson wrote: > > On Fri, Feb 12, 2016 at 9:33 AM, Taceant Omnes <tac...@gmail.com > <javascript:>> wrote: > > I would like to use RS485 with the BBB. > > > > root@beaglebone:~/test# uname -a > > Linux beaglebone 4.1.15-ti-r40 #1 SMP PREEMPT Thu Jan 7 23:32:17 UTC > > 2016 armv7l GNU/Linux > > > > I am using the kernel above. Its source code is at > > > https://github.com/RobertCNelson/linux-stable-rcn-ee/tree/4.1.15-ti-rt-r40 > > You need to rebuild and swap these two configs: > > disable: CONFIG_SERIAL_8250_OMAP > > enable: CONFIG_SERIAL_OMAP > > > ... however it does not include the changes in this patch: > > > https://github.com/RobertCNelson/bb-kernel/blob/am33x-v3.8/patches/fixes/0007-omap-RS485-support-by-Michael-Musset.patch#L30 > > > 485 is pretty much built-in to CONFIG_SERIAL_OMAP > > It's the last thing still being talked about for integration into > CONFIG_SERIAL_8250_* for possibly 4.6.x > > > Which kernel should I use that includes the changes in the patch or > > something similar? > > and use this overlay as reference, as it's been reported to work with > that config chanage above.. > > > https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-UART4-RS485-00A0.dts > > > Regards, > > -- > Robert Nelson > https://rcn-ee.com/ > -- 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 beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/7a1baa26-abe8-400f-a5a2-6b15a046a0b3%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
