Hi Jonathan Thanks for your reply. One of the frustrating things is the changes between board revisions - I am on B6, and there are a set of overlays provided for UART support living in /lib/firmware so that if I go (from my recall so can't get the exact syntax)
echo BB-UART1 > /sys/device/.../capemgr_dev.*/slots then /dev/ttyO1 appears like magic. Great! I am now talking to the UART via hypertrm on my PC. And it appears that the problem I am experiencing may be a kernel issue. I can read from the UART, but the select() and poll() functions that ought to report as to whether data is ready to read in the FIFOs are not doing so. In fact, I have bypassed UART1 and installed an FTDI USB serial device on the BBB - this appears as /dev/ttyUSB0. Now I try select() on that, and it does come back, but only with every other character that I type. If I just read() from the file, I get the complete string. So I am a bit concerned that the Angstrom kernel is not as good as it could be, or needs to be. On Wednesday, 24 September 2014 03:02:27 UTC+1, jfsbac wrote: > > Hi, > > Not and expert here, but I did manage to get communication with a device > connected to UART1. What do you have connected? If there is nothing there > your transmit data will just go off into space. To see data come back you > would have to have a device in loopback mode, or at least the Tx connected > to the Rx. > > I am running the Debian image, and used the ADAFRUIT-UART2 overlay. It > shows up as ttyo1 (thats oh one, not zero one). I have a Sparkfun MAX3232 > module that translates the 3V TTL to RS232 which goes to a little micro > that responds to commands like "/sh/s" and returns some text. I use screen > to type the text commands until I get my C program working on the BBB, or > try javascript. Oh, there are also two Zigbee modules in between the micro > and the BBB creating a wireless RS232 link. > > Hope this helps, > > Jonathan > > On Monday, September 22, 2014 12:35:56 PM UTC-4, Julian Gold wrote: >> >> Oh, my board revision is B6. >> >> On Monday, 22 September 2014 17:34:44 UTC+1, Julian Gold wrote: >>> >>> I've been struggling to get serial comms going on UART1. I have enabled >>> it by creating a service that performs >>> >>> echo BB-UART1 > /sys/devices/bone_capemgr.9/slots >>> >>> and lo! the device /dev/ttyO1 appears. However, with two terminal >>> windows open, doing 'cat /dev/ttyO1' in one and 'echo "wibble" > >>> /dev/ttyO1' in the other results in nothing at all appearing in the cat >>> window. I've tried several combinations of baud rates and flow control, >>> with no success. What am I missing? >>> >> -- 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]. For more options, visit https://groups.google.com/d/optout.
