I'd like to do bidirectional IEEE 1284 communication between a PC running Linux and external devices. Receiving data from the device doesn't have to be particularly fast; nibble mode would be fine.
The PC I'm currently using is a modern small form factor PC, a Livia Z N4200, which as far as I know has no traditional PC parallel ports on it. (There are certainly no connectors for a parallel port, just USB, Ethernet, and video and audio output.) It's running Debian 9.
I've written a simple program to call ieee1284_find_ports() and
print the information in the resulting struct parport_list. The
function returns 0 (success) and fills the struct with information
about three ports:
ieee1284_find_ports=0
portc=3
name=0x278 base=278 hibase=0 filename=/dev/port
name=0x378 base=378 hibase=0 filename=/dev/port
name=0x3bc base=3bc hibase=0 filename=/dev/port
This seems odd because my machine has no parallel ports, as far as I know.
When I plug in a cheap USB to IEEE 1284 parallel port adapter (this
one) with no device plugged into the parallel I/O connector,
/dev/usb/lp1 appears and I see the following in my kernel log:
usb 1-4: new full-speed USB device number 11 using xhci_hcd
usb 1-4: New USB device found, idVendor=1a86, idProduct=7584
usb 1-4: New USB device strings: Mfr=0, Product=2, SerialNumber=0
usb 1-4: Product: USB2.0-Print
usblp 1-4:1.0: usblp1: USB Bidirectional printer dev 11 if 0 alt 1 proto 2 vid 0x1A86 pid 0x7584
usbcore: registered new interface driver usblp
However, re-running my program still produces the same results shown above.
Is the ieee1284 library the correct one to use if I want to use this USB parallel port adapter, or should I be using something else?
Also, why might I be seeing those three more traditional-looking
parallel port devices when I query with ieee1284_find_ports()?