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Original question:

am335x irda mode in Linux

Linux/AM3359: IrDA FIR support needed

Matthias Fuchs30
Prodigy 210 points

Part Number: AM3359

Tool/software: Linux

Hi,

we are using IrDA/SIR communication between two AM335x boards running Linux in our machines. Now we are considering upgrading towards IrDA/FIR mode.

Does anybody use AM335x CPUs with IrDA FIR mode (4Mbit/s)? We are aware that this requires a special FIR kernel driver. Does anybody have such a driver or know of its existance?

Matthias

  • 0
    TI__Guru 55345 points

    Hello Matthias,

    You can ask the IrDA sensor manufacturer whether they are aware of such a driver, they would know the best.

    Best regards,
    Kemal

  • 0 in reply to Kemal R. Shakir
    Prodigy 210 points

    Hi Kemal,

    don't think so. I need a driver for the AM335x UART IP in IrDA FIR mode. The IrDA sensor is likely a more or less passive part.

    Both peers in our setup are Sitara CPUs.

    Regards,

    Matthias

  • 0
    TI__Guru**** 181436 points

    Hi Mattias,

    The serial drier in Linux kernel only supports UART mode for AM335x, but supporting IrDA mode is not implemented.

    Matthias Fuchs30 said:
    we are using IrDA/SIR communication between two AM335x boards running Linux in our machines. Now we are considering upgrading towards IrDA/FIR mode.

    I guess you modified the kernel to enable SIR mode since it is not supported in the Processor SDK Linux kernel. Did you run into any issue when trying to enable FIR mode?

  • 0 in reply to Bin Liu
    Prodigy 210 points

    Hi Bin Liu,

    I added a sysfs attribute to switch between SIR mode and normal UART mode. Not elegant but it works. SIR mode only requires a normal UART with special IrDA pulse shaping. That's what the SIR mode of the AM335x UART does. FIR is totally different. You have special paket framing and it might be hard to feed data to the UART device fast enough. FIR cannot be implemented through a standard tty device. You need a FIR driver that probably must use DMA. We are looking for such a Linux driver or reference implementation.

    I must admit that IrDA under Linux is almost dead and even got removed from later kernels.

    Regards,

    Matthias

  • 0 in reply to Matthias Fuchs30
    TI__Guru**** 181436 points

    Hi Matthias,

    Yeah it appears Linux kernel doesn't support IrDA, and we don't have an example driver for Linux.

  • 0 in reply to Bin Liu
    Prodigy 210 points

    Thanks.

    Matthias