Serial and Parallel obsolete? I think not…
Kinda of a rant but helpful tips for getting past USB for simple Serial/Parallel tasks.
If you’re into micro controllers or playing around with older computer hardware you will notice that it all relies on Serial RS232 or some variant of a serial interface. Granted USB is a type of serial in it’s own way but when you’re using a Micro Controller it will need a ISP programmer that uses a USB to RS232 converter. Works fine and all but it can be costly down the road. Not to mention if you cross-platform micro controllers. Also the mileage will vary depending on that hardware that is being used. A lot of those USB to Serial cable adapters will only pump out 3volts when you need 5volts. The FTDI breakout boards are expensive, if you buy a cheap one you’ll run into problems. You can still fine RS232 add-in cards for desktop computers for a few bucks. I found a couple on Newegg that are about $12.00 and they’re PCI-E as well. Sadly if you’re a laptop user you’re stuck with USB to serial.
When dealing with true RS232 there are times you have to invert the signal and there are three ways I know of. You can use a couple of 2n2222 or 2n3904 transistors and some resistors, a 7404 hex inverter works very well and there is the MAX232. When it comes to a small parts count a hex inverter works better but with the MAX232 you’ll know you won’t run into any issues.
Parallel is still used quite a bit in industrial systems and I myself attend to use it quite a bit for flashing Micro Controllers when I don’t have a serial port on hand. Works great for old laptop programmers since for some reason serial on laptops attend to be under powered. You can find parallel cards for desktops but for laptops you’re kinda stuck. You could try USB to Parallel cables but with Windows 7/8/10 you might be in the dark, Personally I never tried. With that said stick with USB to serial unless you really need Parallel.