What is the baudRate ? Can you spy the communication with an other device ? ( serial adapter rs485/rs232 )
In my case, baudrate 38400 work pretty well, without noise. and please don't UNDERLINE ! Micka, On Mon, Jan 27, 2014 at 10:54 AM, <[email protected]> wrote: > 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]: >> >> 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. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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