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Parallel port hardware

"Jon Slaughter" schreef in bericht news:A7CNi.412$ snipped-for-privacy@nlpi069.nbdc.sbc.com...

Did not find the collission detection but I think the circuit below will prevent any output to be blown providing the level shift you need at the same time.

----+-------+-----+--5V | | | --+---+--2.5V .-. .-. | | | | | 10k| | | .-. .-. | | | | | | | | | '-'4k7 '-' | 10k| | | |56k | | | '-' '-' | | |\\| | | | +---|-\\ ___ | | PIC SPP | | | |-----|___|--+--)---+------ ----+-+-----)---|+/ 2k7 | | I/O control| | |/| | | | | LM339 | | | | | | | | | | /| | | | | | /+|--+ | +-----)-----)-------| | | | | \\-|-----+ | | \\| | | | LM339 | .-. | .-. | | | | | 10k| | | 10k| | '-' | '-' | | | | | | ------------+-----+----------------+--------- GND created by Andy´s ASCII-Circuit v1.24.140803 Beta

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Any PIC I/O pin I am aware of can sink and source at least 1mA. So the 2k7 resistor being the maximum load will prevent damage from I/O current. At the same time, the input leakage current on a PIC input pin is in the uA range. So the 56K will prevent the input to become floating when the output goes tri-state. Some PICs can activate weak pull ups to do the same.

petrus bitbyter

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petrus bitbyter
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Roger Hamlett wrote in news:xZ1Ni.3317$ snipped-for-privacy@newsfe5-win.ntli.net:

I've done that one before. You use bit 5 on the control line.

I've also made a paralell card into an interface for one of those MKE/Panasonic/Creative CD-ROM drives.

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Gary Tait

petrus bitbyter snipped-for-privacy@enditookhccnet.nl posted to sci.electronics.design:

Tends to get stuck at "0" doesn't it?

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JosephKK

"JosephKK" schreef in bericht news:xRrOi.5167$ snipped-for-privacy@newssvr14.news.prodigy.net...

You're right, this circuit will not work. I'll have a second look tomorrow (if I find some time)

petrus bitbyter

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petrus bitbyter

"petrus bitbyter" schreef in bericht news:470a95a2$0$7076$ snipped-for-privacy@dreader12.news.xs4all.nl...

----+-------+-----+-5V | | | +--------------+--2.5V .-. .-. | | | | | 10k| | | .-. .-. | | | | | | | | | '-'4k7 '-' | | |560k | |56k | | | '-' '-' | | |\\| | 2k7 | | +---|-\\ | ___ | PIC SPP | | | |-----+--+-|___|--+--+------ ----+-+-----)---|+/ | | I/O control| | |/| | | | | LM339 | | | | | | | | | | /| | | | | | /-|--+ | +-----)-----)---| | | | | | \\+|--)--------+ | | \\| | | | | LM339 | | .-. | .-. | | | | | | | 10k| | | | |560k | '-' | '-' | | | | | | | | | ------------+-----+---------+--------+----- GND created by Andy´s ASCII-Circuit v1.24.140803 Beta

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Modified circuit. This one will work... unless I made another mistake :)

petrus bitbyter

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petrus bitbyter

petrus bitbyter snipped-for-privacy@enditookhccnet.nl posted to sci.electronics.design:

It passed all my checks. I would like to see what happens in SPICE. I will have to cobble it up, tinker and and see some day.

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JosephKK

row

Oops, I made a mistake. Connected the PIC I/O pin to GND! Which connectoin should be removed of course. Like I did in the schematic above.

petrus bitbyter

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petrus.bitbyter

"JosephKK" schreef in bericht news:3f3Pi.2357$ snipped-for-privacy@nlpi069.nbdc.sbc.com...

Spiced it using LT1011 as I have no model of the LM339. Seems to work ok.

petrus bitbyter

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petrus bitbyter

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