Am Montag, 25. April 2016 16:10:50 UTC+2 schrieb Taceant Omnes: > > On 25 April 2016 at 12:31, florian.feldbauer85 via BeagleBoard > <[email protected] <javascript:>> wrote: > > Hey all, > > > > I did some further tests. > > Actually none of the screens from my scope looks like I would expect > it... > > > > Picture 1 shows the result, if I try to read something on the bus with a > 14s > > timeout (nothing was sended on the bus...) > > Pic1 > > Picture 2 shows the same, but this time there were messages send over > the > > bus. After 49 bytes, the beagle bone toggles the DE/!RE gpio to high for > > unknown reasons (the test program is still reading from the UART > interface) > > Pic2 > > Picture 3 shows the test, where the BeagleBone is sending > > Pic3 > > and finally picture 4 shows a test, where the BeagleBone should read > > (timeout 3s) on the bus, then send something and again reading (with 3s > > timeout)... > > Pic4 > > As you see, DE/!RS stays high after sending, although it should be > low... > > > > In addition I would expect this line to be low when the port is not > used, > > but it's high.. > > > > I checked if there is any other process (or driver) accessing GPIO3_19 > but I > > could not find any... > > > > Any help is very much appreciated! > > Any chance you could post a picture of a simple drawing of how you > connected the 485 driver to the BB (like which pin to which pin and > any extra components)? Also could you post your small C test program? > Hey,
@Alex: I recommend, you read my mail ;-) I did not look into the kernel source nor am I sure which driver is used in my Setup, but the problem is not the "*rs485-rts-active-high" *flag When sending, the RTS (or DE/!RE) signal behaves as expected. Only during receiving (and IMHO when idle) the flag does not. here is the schematic of my current test setup. <https://lh3.googleusercontent.com/-KYAgv2mNX90/Vx8Q-xLnxQI/AAAAAAAAD8c/OCGnQLbhFMkUoazA8fyg3Fm-vxbpOww2wCLcB/s1600/bbb-rs485-connection.png> Concerning my test program : rs485_test.c <http://www.ep1.rub.de/~florian/rs485_test.c> (it's a ugly quick'n'dirty implementation...) The RS485 line driver is connected to a RS485-RS232 Converter which is connected to a linux PC. On this linux PC, the same program is used for the tests. Cheers, Florian -- 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/59b26949-f87c-4159-86e7-779af5c8ecd4%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
