anotherbrick
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I build a digital input / output board for paralel port of PC
I run setup of PC while booting and set the paralel port to EPP mode
when sending bytes to the I/O board everything runs perfect - I can set and reset outputs and so on
but when I try to read from the board - I realized (while looking at the osciloscope) that the paralel ports data port still try to drive the data lines - My circuit try to give a "0" to a data line - the paralel port tries to pull it high ("1",the last information which was output) - so i read wrong data from the board
In the Jan Axelson's book it says make the control port bit 5, "1" for reading from outside world
I did the bit 5, "1" - nothing changes
the data port still tries to drive the data lines
does anybody have an idea ? how can I overcome this ?
I run setup of PC while booting and set the paralel port to EPP mode
when sending bytes to the I/O board everything runs perfect - I can set and reset outputs and so on
but when I try to read from the board - I realized (while looking at the osciloscope) that the paralel ports data port still try to drive the data lines - My circuit try to give a "0" to a data line - the paralel port tries to pull it high ("1",the last information which was output) - so i read wrong data from the board
In the Jan Axelson's book it says make the control port bit 5, "1" for reading from outside world
I did the bit 5, "1" - nothing changes
the data port still tries to drive the data lines
does anybody have an idea ? how can I overcome this ?