From: Davison, Lee (Lee.Davison_at_merlincommunications.com)
Date: 2003-10-09 00:26:47
'Lo all, > I'm just forwarding this question to the cbm-hackers mailing list, as there > are some people who might know more about this. >> There must be a way to protect the parallel port using simple components. There is, simply connect a resistor in series with each bi-directional line you wish to protect. A value of 180 to 220 ohms should work. One thing to note is that this may delay the signals if you're trying to make high speed transfers, it may also reduce the noise immunity on longer cables. It may help to put the resistors all at the mostly receiving end of the cable or, if the data goes equally both ways, split the resistance between both ends of the cable. At worst this will nearly double the signal speed compared to the single resistor solution. > I think the maximum sourcing und sinking current of the parallel port is not > really defined There is more than one "maximum current" limit. The lowest one is usually the maximum that can be sourced or sunk and the output still be within the defined voltage limits for the logic levels for the device. This is usually only a few mA at best. The next is the short circuit current that can be sourced or sunk by one pin, this can be a couple of hundred mA. Lastly is the maximum current per package before you let the magic smoke out, this can be half an amp or so but isn't recommended as common practice. Lee. ________________________________________________________________________ This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________ Message was sent through the cbm-hackers mailing list
Archive generated by hypermail pre-2.1.8.