User:Legolas558/New JD-ICE interface
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This message was originally stored at http://sourceforge.net/mailarchive/message.php?msg_id=15520486, which now leads to another project's messages!
See also Talk:JD-ICE interface
EPP emulation
Quoting a FAQ from http://www.lvr.com/jansfaq.htm
Q: I'd like to power a low component count device via an output port bit on the pc's parallel port. Does anyone know the current sourcing spec for an output port bit?
A: The data outputs on the original parallel port were 74LS374 outputs, which can source 2.6 milliamps at 2.4 guaranteed, 3.1V typical. The data outputs on most parallel ports are at least as strong as the original port's, but no guarantees. If you need 5V, you can use one of the high-efficiency step-up regulators from Maxim & others (Max756). The newer port controller chips often have IEEE-1284 Level 2 outputs, which can source 12 milliamps at 2.5V. The Control outputs were originally open-collector TTL with 4.7K pullups, so these are less useful as current sources.
Another interesting quote:
Q: I need to make an interface to emulate a printer that is on-line and with paper. I have a program that needs three printers, but two of the outputs don't interest me and if I don't have the printers connected, the program doesn't work.
A: To fool the software into thinking that a printer is connected, try this: Tie -Error (pin 15) high (+5V). Tie PaperEmpty (pin 12) low (0V). Tie Busy (pin 11) low (0V). Matthew Chapman also recommends tying -Select (pin 17) low and pin 12 (Select In) high.
John Sawyer successfully used this wiring to emulate a printer connection: 1 (data strobe) ---> 10 (Ack) 11(busy) , 12(paper end), 17(select inhibit) --> Ground 13(select) --> 15(!error) --Tied together, but floating
JD-ICE redesign
If somebody want to redesign JD-ICE, this is the moment to pop out. The main features the new interface should have are: - printer emulation circuitry to allow using standard printer output for the IO communication. - SAFE power source taken from unused LPT pins
The above two must be designed taking in account MAXIMUM compatibility amongst hardware. I will take care of the software compatibility. Basically, take the LPT electrical pinout of the oldest working printer and simulate that.
- LED to show power on/off of the interface (and clock LED if you like...) - transistor to turn on/off the player
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Legolas 28/04/2006 12.49 GMT+1
