Digital Interface Basics
After a long time a thread of discussion. It is about digital interfacing of embedded system. Only Education Points listed. Initials and country of origin also will not be mentioned henceforth.
When this Circuits FAQ started decades back around 2000, It was a PHP mail form called “Problems and Solutions”. The mail was coming like 3-4 every day.
Hello Sir. I am looking for someone that can help me with simple challenges from time to time, deciding on best electrical components and designing wired circuit diagrams to my specifications. Thank you!”
Only the delabs Answers are Reproduced Here
The output logic of your embedded system port bit (one pin) goes high it can drive a drive a ULN2003A. – The output of this is open collector and can operate relays or lamps.
The Proximity Sensor can be turned on with an external PNP power transistor if the current consumption of that is above 300mA. It is not a good idea to heat The ULN2003A chip too much. Keep the return paths of these to a separate but linked ground as they carry more current.
If you are running short of ports in the Embedded System. Latch the Output by using 74HCT373. There may be logic level comparability problems check your Embedded System Supply. There may be ground loop problems.
Use ULN to drive PNP Transistor and things like a Relay, Lamp or your Proximity Switch.
It is important to learn and do things, this is the real electronics. Do not overload any device, study current and voltage ratings. Keep Mains HV and High Current circuits that are dangerous in another card with optoisolaters.