Hello everyone ,

I have a peripheral (LCD) that connected to the parallel port 1.I have some questions hope to find answers


1-what are the representation of bits in control registers on PCSPP mode?
bit3 --> selector ----> inverted
bit2 --> reset ----> non inverted
bit1 --> feed line ----> inverted
bit0 --> enable ----> inverted

is this true for PCSPP mode?


2-when using outb() macros in C language is it possible to reach the following timing diagram

sketch after call ioperm() etc...

outb(0b0011) , Par_Port_Control_reg);
usleep(50);
outb(0b0010) , Par_Port_Control_reg);
usleep(20);
outb(0xf9 , Par_Port_Data_reg);
usleep(50);
outb(0b0001 , Par_Port_Control_reg);

will this code lead to this diagram if not how to reach to something like this

http://prntscr.com/r5bi9q


Thank you.

Parallel ports went out about 15 years ago. They used fixed I/O & interrupts and memory was made contiguous. Have you an old box or a pci parallel port card? How old is your information?

I'm a hardware guy who remembers that time. I'd advise you to scrap that lcd unless you're running a museum.

well I have no other option rather than parallel port to communicate to LCD.

I have read that in PCSPP mode the control register bit3,1 and 0 are inverted except the bit 1 reference:https://en.wikipedia.org/wiki/Parallel_port

but when trying to write code based on that bits mapping nothing work on LCD.

Thank you

I have had fierce trouble with parallel port drives. Notably,

1. What works on one parallel port may not work on another
2. Connector errors are very common. The pins are usually numbered in tiny writing on the plug, but errors are frequent.
3. Voltage thresholds vary

Have you an oscilloscope?

Have you an old OS & pc or a pci(e) card? Why do you want to send ascii a (presumably) old lcd anyhow? Student project?

I can't get yuou past 1st base unless you give some answers

No I don't have oscilloscope ,OS is ubuntu 18.04 and the hardware components are not old.Pardon me why did you mention the pci port?

I tried to change the value of timeslice and spintime I thought they may effect but when I try to change their values I got invalid parameter message.

Actually do they make different?

I mentioned pci because I didn't think any sane manufacturer was still putting parallel ports out, except, perhaps in the occasional Industrial PC.
The last Windows version to support parallel ports was XP, AFAICT. Serial port, parallel port & floppy disks all had fixed I/O & predetermined hardware interrupts, which work against contiguous memory. Does your kernel support it?