Question about nAstrobe and nDstrobe in EPP mode

[wireless]

initialize epp register

hi

I am using the parallel port in EPP mode for my project... but i'm having some doubts...

When i'm doing a Address Write, how come both the nAstrobe and nDstrobe are in Synch with each other in pulses.... i thou that when doing Address Write, nDstrobe should be high and nAstrobe should be low... i'm getting the same thing as well when doing Data Write....

And the pulses i'm getting for both nAstrobe and nDstrobe are less than 1V... why is that so... i'm expecting it to be prob 5V...

cheers

 

[nex]

force epp mode

Is your EPP port OK ? What do you connect to EPP? Did handshake ?

 

[Tomby]

winio.dll 0x378

What address did you write the data values to anyway? EPP Mode has 8 registers.

Base address is for SPP Data
Base address + 1 is for SPP Status
Base address + 2 is for SPP Control
Base address + 3 is for EPP Address
Base address + 4 is for EPP Data
While the other registers from 5-7 are varying.

If you're using EPP mode, you have to write the address to register Base address + 3 and the card should automatically generate the handshaking signals for you. The same goes when you are writing data to base address + 4.

 

[mandrei]

epp programming

Dear wireless

Here is the answer to your question:

After boot the parallel port of the PC default to SPP (standard paralel port) mode.
In SPP mode, te strobing mechanism of the EPP mode is disabled (no auto-strobing).

Therefore to force the paralel port from SPP to EPP mode you MUST execute the folowing instruction:

// set parallel port to EPP mode  
outp(Base_Adress+2,0x04);

Where Base_Adress is the adress of your parallel port.

example:

#define Base_Adress 0x378  // LPT1 address

It works like magic, just try it !!!

 

[nex]

Re: EPP transfer

Dear wireless

After boot the parallel port of the PC default to SPP (standard paralel port) mode.

It works like magic, just try it !!!

Hi mandrei,

Even if you set EPP from BIOS ?

Cheers !

 

[mandrei]

Re: EPP transfer

Dear nex

Verry interesting and hard to answer question!!

Here is my opinion:

I mantain my opinion that after boot, the PC paralel port is in SPP mode (mybe i'm wrong...)

Enabling the EPP mode in BIOS is absolutely necesary to work with Paralel Port in EPP mode (thank U 4 observing this important setup!!).
This only will enable the EPP hardware after boot, but the EPP port mybe is not corectly initialized.
So, after boot, some "manual" clean-ups must be made using SPP mode (see the "magic" instruction), in order to corectly initialize the EPP port.

Here is an article about this problem (read especialy "EPP Programming Considerations" section).
Maybe we will found the corect answer together!!

 

[pico]

EPP transfer

You can find more information from here.

**broken link removed**

 

[nex]

Re: EPP transfer

Dear nex
I mantain my opinion that after boot, the PC paralel port is in SPP mode (mybe i'm wrong...)
So, after boot, some "manual" clean-ups must be made using SPP mode (see the "magic" instruction), in order to corectly initialize the EPP port.

Dear mandrei,
I think that Windows read the BIOS only that counts
Some time ago, I hook'up a 16F877+HDD to parallel port. I made the software(VC6) thru winio.dll... I never setup the port... In fact I choose EPP mode in BIOS . Had some problems with handshake... Did a loop to cacth DataStrobe... After that all was OK .

Cheers !