4,199
edits
Changes
From IGEP - ISEE Wiki
m
→Add RS-485 support to Linux
At any point, if you see a mistake you can contribute to this How-To.
= Add RS-485 support to Linux = === Using kernel 2.6.35.13 === In this kernel is not necessary add RS-485 support === Using kernel 2.6.33 series === Follow http://www.igep.es/index.php?option=com_kunena&Itemid=97&func=view&catid=13&id=1195&limit=6 === Using kernel 2.6.28 series === Tested on a 2.6.28.10-3 version kernel. To use correctly the RS-485 interface chip we need to configure the serial port driver in the kernel to manage the RTS signal (Request To Send) to enable the TX section (DE pin) only when data are transmitted on TXD line (Transmit Data). This is a software only solution, requiring no special hardware, but timing control for delays is only accurate to the next nearest jiffy. First of all, download the latest stable kernel version $ wget http://downloads.igep.es/sources/kernel/linux-omap-2.6.28.10-3.tar.gz $ tar xzf linux-omap-2.6.28.10-3.tar.gz $ cd linux-omap-2.6.28.10-3 $ make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- igep0020_defconfig Next, enable the RS-485 support. $ make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- menuconfig Configure the kernel to enable RS-485 support. Device drivers ---> Character devices ---> Serial drivers ---> *** serial port extensions *** [*] Allow hand shake line half duplex direction signaling Finally build kernel image with RS-485 support $ make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- uImage
= Test RS-485 communication with two IGEP0020 boards =
