How to find the base address of usb to parallel port device in Linux?

4
votes

I am doing IO programming in C in Ubuntu. And I need the base address of the port to write data.

My laptop dont have a parallel port. So I bought a USB to Parallel port connector. I plugged in the device and its getting detected in /dev/usb/lp0

I ran "lsusb" to see the list of devices and I can see the ID also. But how can I get the base address ? For the usual hardware parallel devices, the base address is 0x0378. this address is not getting detected while using USB to Parallel device.

Please help.

2
clinuxlinux-kernel
An USB to parallel adapter is not suitable for the classic style of LPT programming because it doesn't reside in the address space at all! If you want to do classic LPT programming, consider buying an LPT card for the PCI or PCIe bus. – fuz

2 Answers

5
votes

A USB parallel port doesn't have a base address - it's not a meaningful concept for USB. I'm afraid the days of doing I/O on PC hardware via in and out instructions ended a few years ago, though lots of old tutorials still survive on the web.

You can write bytes to the parallel port as a character device, and these will appear on the printer port pins. The USB adapter will expect the other end to handshake data exactly like a printer. If you want to do general I/O prototyping, you're probably better off with a simple USB microcontroller like an Arduino.

Further discussion here.

2
votes

If you are still interested to use this USB-to-parallel-printer device for your own bit-banging, it's important to know that their built-in firmware always allows controlling of D0..D7, INIT (as outputs), /ERR, ONL, PE (as inputs), but never for /ACK, BUSY (inputs), /STB, /AF, /SEL (outputs) pins. And you need an 8-bit latch (e.g. 74HCT574) for catching data while strobing.

See here (https://www-user.tu-chemnitz.de/~ygu/bastelecke/PC/USB2LPT/faq#DIY) especially for possible data rates.

Accessing from software side is a bit complicated but possible, and you may have to re-structure your software and hardware for making such adapters useable. I don't know for Linux case how to access, but IMHO you don't need to write a kernel-mode driver.