> Hello, > > I am working on a project in which I must use RTLinux as real time support to > implement a modem. I have already made a program working on "normal" linux > which simulates the process and now I must port it to RTLinux. I will use > dac/adc boards to get data in and out the pc. The modulator must periodically > generate some data, map it on some kind of signal symbols and write the simbols > in the dac channel. The demodulator must read the symbols from the adc channel > and invert the process. > > In the porting to RTlinux two questions arise: > > 1)We must buy the dac/adc boards: What do I need for them to be able to work in > RTlinux? Can a Linux driver do? Or does the driver have to be specially > implemented for RTLinux? And if this is the case, do vendors provide that kind > of drivers? Are they easy to find by other means if they don`t? Does anyone > know about some specific board model which can work in RTlinux without many > problems?
There are vendors that provide RTLinux drivers - but generally writing a ad/da driver for RTLinux is not a big deal if you get proper (and corect documentation from the vendor...) Concerning the special implementation of RTLinux drivers - they are structured completly different and generally will be simpler than Linux drivers. One of the concepts is to have a rtlinux module that just provides low level analog_get analog_put digital_get and config functions like chanel select etc. these low level functions generally will be a few inb/outb instructions and then are called by a rt_thread that does the processing or the comunictaion to the non-rt side. There is no need to implement read/write/select/mmap/open/releas methods for Linux - init module simply will register the device and put it into some sane state - the actual data sampling is then done with the low level functions from the rt-thread. Concerning boards that should be easy to write drivers for you would need to specify a bit more details of what this board needs to provide, interrupt driven or polling how many chanels in what bit-width etc. > > 2)In the porting of the c code: Will I have severe limitations in trying to put > my code into the kernel modules and the RTtasks?I mean, will I be able to use > in RTLinux all the functions I use in mi Linux made code? I have read that > functions like printf or some math functions canīt be called from a module. Why > is this? What kind of code do they execute for them not to be able to be called > from a module? You can't use printf in your kernel module - you can print to the console thoughor to the kernels ring buffer. There are no real limitations that you would not find in a normal linux kernel module - if you need floating point math in a module you need to folow the proceedure outlined in the example/fp/ directory - the modules will tend to be large as you need to statically link libm but other than that there are not fundamental limitations. hofrat -- [rtl] --- To unsubscribe: echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED] -- For more information on Real-Time Linux see: http://www.rtlinux.org/
