[vdr] Re: [linux-dvb] wake on remote

Marko Mäkelä marko.makela at hut.fi
Sun Sep 11 22:59:26 CEST 2005

On Sun, Sep 11, 2005 at 07:14:22PM +0200, matthieu castet wrote:
> For keyboard, mouse, serial port it is trivial via /proc/acpi/wakeup.
> But for our case we should have a dvb (pci) card that allow to keep the 
> remote device active when we shut down the computer and to send a wakeup 
> even.
> So I fear it is card specific and even could need some driver code to 
> activate this feature.

The cx23882 that is used at least in budget DVB-T cards has some GPIO
lines, one of which typically is connected to the infrared receiver.
Since the pulses from the remote control unit will be decoded by the
driver (in Linux 2.6, it would be cx88-input.c for this chip), there
is no way for the hardware to detect if the Power key was pressed.
I would assume that the situation is similar with other cards featuring
a remote control unit.

Waking on any pulse from the infrared receiver module would not make
any sense, since the receiver will deliver false pulses every now and

For what it is worth, I have built a simple microcontroller circuit
that sends a Wake-on-LAN event when the Power key is pressed.  The
prototype is connected to the cable of the infrared receiver module.
The next version will be a small circuit board that will be attached
to the PCI card.  I should get the board milled soon.

My firmware will even signal the PC if it was powered on by remote,
but receiving that information requires a patch to the kernel driver.
(If I were able to use LinuxBIOS, I'd possibly deduce the source of
the power-on event from the chipset of the motherboard.)

My wake-on-remote circuit and firmware are available at
<http://www.funet.fi/~msmakela/electronics/worc5/>.  Note that the
upcoming daughterboard will have the I/O pins connected in a slightly
different order, to allow the microcontroller to be programmed
in-circuit while the computer is powered on.  I will of course update
the page as soon as I have assembled and tested the daughterboard.


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