Re: using multiple usbasp connected to PC in the same time

[Joerg Wunsch]

As Klaus Rudolph wrote:

> I have no idea how avrdude internally is searching the device, but it
> looks like that it scans over all usb busses until it finds a device of
> given type.

This is the way USB works, in general.

> If we are able to restrict the found device type to a specific hardware
> address like: pci-0000:00:14.0-usb-0:1.6:1.0 like we can do in udev
> rules, we can address each one individual.

libusb abstracts the underlying OS. libusb_device is just an opaque
pointer to an implementation-defined struct; any details about how
that OS handles the hardware access is hidden, and cannot be used by
an application on top of libusb.

So, a portable application has to rely on the USB model, which means
to use serial numbers to distinguish devices. As an alternative, see
my previous proposal: the infrastructure for that is already
implemented in AVRDUDE right now.

If you were to propose USBasp could also handle serial numbers, I'm
not opposed to adding that functionality in AVRDUDE. However, it's my
understanding that USBasp's goal was merely to provide a simple
standalone ISP programmer for the casual AVR developer, so they
deliberately left out the serial number feature. (There are other
programmers around providing that.)

-- 
Joerg Wunsch