Hi All, I have a interesting issue:
What I have did is: - Downloaded Angstrom linux - Applied RS485 patch - Compiled kernel image and push it to BBB. Now I have developed two applications: 1. send.c : This application periodically sends the data on UART 2. recv.c: This application waits to read the data from UART. Both above application works pretty well without any issue. Even I do not have to manually drive the GPIO. (Driver patch handles GPIO value perfectly.). *Problem:* *Now, I have developed an application which is combination of both send and recv. I mean , after sending one byte on UART from BBB to other host machine, I just wait for input bytes to receive(added receive timepout at 10 sec). Now in this cae, even if I do not send any character from host machine, BBB detects one/two arbitary bytes. This seems that driver changes GPIO position (from send mode to recv mode) before transmitte buffer gets empty. * Did any one has face this problem? Can you guys please share your thoughts on this? Thank, Ashish On Tuesday, December 3, 2013 11:23:48 PM UTC+5:30, [email protected] wrote: > > Zach, > > That is great info! > > Thanks a bunch, > > Haik > > On Tuesday, December 3, 2013 11:42:10 AM UTC-5, Zachary Thorson wrote: > >> I am using a custom built cape for my application, so I have not tested >> it. Though according to the schematics it looks like the chip does not >> support those rates. >> >> According to the schematic at: >> http://beagleboardtoys.info/index.php?title=BeagleBone_RS485 >> >> It looks like the RS485 cape uses a TI transceiver part no: SN75HVD12D >> http://www.ti.com/lit/ds/symlink/sn75hvd12.pdf >> >> >> <https://lh6.googleusercontent.com/-iazVOLORISQ/Up4HgMpjUQI/AAAAAAAAA54/FZqOvYcHf28/s1600/12-3-2013+10-31-36+AM.png> >> >> Should be able to go up to 1Mbps, but not much higher. >> >> Checking the ARM Datasheet (AM335x ARM Cortex -A8 MPU Technical Reference >> Manual): >> >> 19.1.1 UART Mode Features >> The general features of the UART/IrDA module when operating in UART mode >> are: >> >> - 16C750 compatibility >> - Baud rate from 300 bps up to 3.6864 Mbps >> - Auto-baud between 1200 bps and 115.2 Kbps >> >> >> Since on the ARM side, you have slightly higher max data rates, so if you >> had a faster chip you could approach the rate you need given the right >> design. If you need faster than what is natively on the ARM, you could >> look into a custom solution with the PRU, but I don't have any experience >> with that. >> >> >> Zach >> >> On Tuesday, December 3, 2013 6:17:45 AM UTC-6, [email protected] wrote: >>> >>> Hi Mika, >>> >>> I need to go two orders of magnitude higher (3.8 Meg, for a short >>> distance of six feet, half duplex). Is there a chance with BBB? >>> >>> Thanks, >>> Haik >>> >>> On Tuesday, December 3, 2013 3:40:39 AM UTC-5, Mickae1 wrote: >>>> >>>> Hi, >>>> >>>> Well, I'm working with the BaudRate 38400 and I don't have any problem. >>>> I didn't try further. >>>> >>>> micka, >>>> >>>> >>>> On Tue, Dec 3, 2013 at 3:13 AM, <[email protected]> wrote: >>>> >>>>> Hi all, >>>>> >>>>> Interesting Work! What is the max baud rate you can get from this >>>>> rs485 cape on BBB? >>>>> >>>>> Haik >>>>> >>>>> >>>>> On Friday, June 21, 2013 5:54:29 AM UTC-4, Mickae1 wrote: >>>>>> >>>>>> Hi all, >>>>>> >>>>>> Yes I did it ^^, I successfully made my BBB ( Kernel 3.8.x ) work >>>>>> with the *RS485 CAP ( I was able to talk with my PC with a >>>>>> USB<>RS485 adaptater ) * >>>>>> >>>>>> To do it, I modified the Kernel (omap serial driver) and I tested it >>>>>> on a Ubuntu Distribution ( Why ? Because I don't know how to modify the >>>>>> source code of the kernel with an angstrom distribution. And Robert >>>>>> Nelson >>>>>> explain very well how to do it with a Ubuntu distribution). >>>>>> >>>>>> It's true, that the eMMC use the GPIO1_0 & GPIO1_4 of the BBB and the >>>>>> RS485 cap need them, but it's also *easy *to disable the virtual cap >>>>>> eMMC! Just a simple echo -4 > $SLOTS do the trick. >>>>>> And I also had to create my own rs485 virtual cap to enable the >>>>>> GPIO1_0 & GPIO1_4 & UART1_TX & UART1_RX >>>>>> >>>>>> But now, for my project I need to cross compile, and it looks like >>>>>> that there is no toolchain on the ubuntu distribution (working with the >>>>>> Robert Nelson Ubuntu distribution). >>>>>> >>>>>> So I'm going back to the Angstrom distribution, but my problem is >>>>>> that I don't know where to put my patch ? Will it work ? I don't know >>>>>> how >>>>>> to create a patch, I just did this command : " sudo git diff > >>>>>> ../rs485.patch" ( Robert Nelson => on your KERNEL folder ) >>>>>> >>>>>> I read here => http://downloads.angstrom-distribution.org/demo/ >>>>>> beaglebone/ >>>>>> >>>>>> That i can create my own image, with this : >>>>>> >>>>>> git clone git://github.com/Angstrom-distribution/setup-scripts.git >>>>>> >>>>>> cd setup-scripts >>>>>> >>>>>> ./oebb.sh config beaglebone >>>>>> >>>>>> MACHINE=beaglebone ./oebb.sh bitbake systemd-image >>>>>> >>>>>> >>>>>> My question is where I can put my patch ? Or where I can modify the >>>>>> Kernel ? >>>>>> >>>>>> >>>>>> Thx you every one, It's because of your help, That I was able to make >>>>>> this Work ! >>>>>> >>>>>> >>>>>> I will soon explain my work on this project in my blog. >>>>>> >>>>>> >>>>>> >>>>>> Michael Musset, >>>>>> >>>>> -- >>>>> 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/groups/opt_out. >>>>> >>>> >>>> -- 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/groups/opt_out.
