Yes, Dont solder Rx-serial to Rx-CAN-bus. The email/posts above are concerning the RTS pin and allocating another BeagleBone to it: the DMA one and not GPIO one
On Thu, Apr 18, 2019 at 6:46 PM <[email protected]> wrote: > Hello > may be there is wrong hardware design with Waveshare RS485/CAN Cape. I > don't think is good idea to connect RS485 driver RX pin to CAN driver TX > pin. if you desolder can driver rs485 should work fine. > > br > harry > > On Tuesday, March 28, 2017 at 3:52:07 PM UTC+3, 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 a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/beagleboard/JGIm0Ej6jDI/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/0ef1a012-13ed-4a33-9443-6b0cbefc322a%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/0ef1a012-13ed-4a33-9443-6b0cbefc322a%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/CANPM5qXQbe%3DBsJCneuPvUM%2BdqGQpsV5aFS-Q23bniXZh0eYi_A%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
