Differentiate multiple USB programmers of the same VID/PID (libusb or hidapi or libftdi)

[mcuee]

Ref: the following enhancement requests talk about usbasp

• [patch #7321] usbasp: filter usb serial number #619
• [patch #9254] Adds support for selecting USB devices to USBasp #718

But this can be extended to other USB based programmers. If you have multiple programmers of the same types connected, the best is to differentiate them by serial number. Or you can differentiate with the Manufacturer/Product strings. Then there is another possibility is to use the locations (USB ports).

[mcuee]

Specific to hidapi: at least you can get the vendor_id, product_id, path, serial_number.
Ref: https://github.com/libusb/hidapi/blob/master/hidtest/test.c

[mcuee]

For libusb, same that you can get the vendor_id, product_id and serial_number. You can also get the path using libusb_get_bus_number and libusb_get_port_number.
https://github.com/libusb/libusb/blob/master/examples/xusb.c

[mcuee]

For libftdi, ftdi_usb_get_strings() can probably be used.
https://www.intra2net.com/en/developer/libftdi/documentation/ftdi_8h.html#a17e8eae09e58bd3bfeeab8decfce7fd9

[mcuee]

Ref: OpenOCD libusb-1.0 helper may give some hints as well.
Ref: https://github.com/openocd-org/openocd/blob/master/src/jtag/drivers/libusb_helper.c

It can be done using libusb-0.1 API as well since avrdude is still mostly using libusb-0.1 API.

[MikeRaffa]

I have some working code for USBASP, specifying programmer with -P usb:xxx:xxx.

Any interest in adding this to the project?

[dl8dtl]

How did you solve the multiplatform aspects? (Windows, Linux, MacOS, BSD)

[MCUdude]

Any interest in adding this to the project?

It would be great if you could create a PR for this! usb_libusb.c and usb_hidapi.c already reads the serial number from the device and store this in a string, usbsn, but it looks like usbasp.c uses libusb directly.

[dl8dtl]

As a remark (since I once implemented the serno matcher in stk500v2/jtag): serial numbers can sometimes be long, and it makes most sense to just match the trailing part. (OpenOCD requires the full serial number, which is hard to type when typing manually on the commandline.)

[MikeRaffa]

Sounds like there's some value to potentially adding that. I'll do some cleanup/testing and then submit something if it looks like it's working.

I've only tested on Linux so far. I could check on Windows/Mac as well; not sure what the usblib differences are there. The method I'm using is by USB bus (usb:xxx:xxx). Not sure if serial no. is prefereable.

[dl8dtl]

Using a serial number is much preferable – however, I'm afraid most (all?) USBasp implementations just don't offer a serial number at all.
For devices lacking a serial number, it might make some sense to offer alternative ways to distinguish different programmers. But then, I'm afraid every operating system needs to be treated differently.
Either case, please don't forget to update the documentation, or at least to provide a text block we can include into the documentation files. (We can handle the respective markup if you are unfamiliar with that.)

[mcuee]

For devices lacking a serial number, it might make some sense to offer alternative ways to distinguish different programmers. But then, I'm afraid every operating system needs to be treated differently.

The USB bus:port number may be another way to distinguish the devices: libusb_get_port_number() and libusb_get_port_numbers(). But then libusb-1.0 API is needed.
https://libusb.sourceforge.io/api-1.0/group__libusb__dev.html#ga14879a0ea7daccdcddb68852d86c00c4
https://github.com/libusb/libusb/blob/master/examples/listdevs.c