Hi Mat, I have the same issue: any response yet?
On Tuesday, March 28, 2017 at 2:52:07 PM UTC+2, Matthew Bezuidenhout wrote: > > Hi all, > > For days now, I've been attempting to get the Waveshare RS485/CAN Cape to > work on Beaglebone black. > > I've used kernels 4.4.x and 4.9.x-ti mainline, and encountered the same > problem. > > The cape can use any UART (have been trying with one), and requires the > use of pin P9_42 (0x164) as an RTS pin. > > The dtbo (standard from https://github.com/beagleboard/bb.org-overlays > which uses pin P9_27) loads fine using > > echo BB-UART4-RS485 > /sys/devices/platform/bone_capemgr/slots > > A "cat /sys/devices/platform/bone_capemgr" reveals the slot has been > loaded correctly. > > The HDMI has successfully been disabled. > > Three problems arise: > > PROBLEM 1: > The wavheshare cape requires the pulldown of both UART pins (I used > UART4), as it leaves the pins floating through the RS485 transceiver if > left standard. Now, the tricky thing is, if I enable BB-UARt4-RS485 in the > /boot/uEnv.txt file, it loads the cape fine, but will not do pulldowns. If > I allow the beaglebone to boot, then echo the BB-UART.... at slots, the > pulldown works and the transceiver can send a signal through, which is > curious as it is exactly the same dtbo it loads, whether from uEnv.txt or > echo. > > PROBLEM 2: > Once loaded using echo after start, if I "cat /proc/tty/driver/serial" > immediately after loading UART RS485 overlay, the flags I'm presented with > are as below: > > 0: uart:8250 mmio:0x44E09000 irq:158 tx:8304 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:198 tx:0 rx:0 CTS|DSR > 5: uart:unknown port:00000000 irq:0 > > > Showing UART4 (the one I'm using) has not loaded the CTS and RTS flags > appropriately. However, if, before performing the cat, I screen into ttyS4 > or ttyO4 or echo some characters at the port, and then I perform the "cat" > as above, the RTS and DTR flags are both raised on 4. Thereafter, if I > screen in on ttyO4, and then quit, the RTS flag disappears after a cat. > Weird. > > However, regardless of these results, I'm left with the following main > problem, > > PROBLEM 3: > Regardless of the flag position or whether I use the default > BB-UART4-RS485-00A0.dtbo from the source, the RTS pin does not switch (both > P9_27 and P9_42 are unresponsive to any efforts to communicate on the > UART4, where the UART transmits as evidenced by the oscilliscope, but the > oscilliscope shows that the RTS pin P9_42/27 does not move at all). I need > to get pin 9_42 to switch for RTS during uart, else this cape (and the > beaglebone) are useless to me. > > After copious amounts of time reading up on this, it seems that its a > common problem, and something to do with the OMAP serial driver vs the 8250 > driver malfunctioning? If someone could provide some insight to the > problem, or a guide on how to get RTS working on this Beaglebone I'd be > very appreciative. > > Kind regards, > Matt. > > > -- 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/efb2fc13-4e78-4693-87d0-f35e5b7ed7a1%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
