Hi experts,
im currently coding a simple read/write library for use between host and a power supply. I know how to read and write on the bus so thats solved, but i keep getting "bus time expired" because i cant get it synchronized. The power supply generates a interrupt on IRQ7 when it puts data in its output port. How can i use this? I'm completely noob, i've been reading about interrupt handling in the linux device drivers from 2005. But i'm having a bit of a struggle getting my head wrapped around it. So can anyone give me some pointers? I'm really only interrested in how i can get my function to wait with reading until the ps send the interrupt.

Thanks in advance

You are probably working at too low of a level, and you are also tackling a task that has already been done. (Linux systems have been shutting themselves down when power dies, for many ye ... )

The port (a serial port?) is simply a device, and you should have (and BTW there already exists...) a daemon that can start an asynchronous read upon the port (uses a mechanism like poll() ...) and be woken up when the read completes.

IRQs and such are the lowest-level glue when talking to a device, and "a port is a device ... a power-supply is not ... and we already know how to talk to a port."

When the daemon decides that power has been lost, it notifies the kernel to switch to a different runlevel, thereby bringing the system to a stop.

Okei, ive maybe been a bit unspecific. When main power cuts and the operating system is doing some operation the computer have crashed.... Therefore i've acquired an UPS(my device ), and now i'm trying to write a program which reads from the UPS when it goes from AC power to batteries. But i can't get the I/O operations synced without the ability to know when the UPS sends an interrupt on the parallell which indicates that its put new info on the bus.

But thanks for answer, been glaring into the screen for hours now (N)