Test Measurement - Multi-Meters, Small Test Tools.

Monday, January 29, 2018

Digital Interface Basics

After a long time a thread of discussion in Gmail and Telegram (first time). 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. Now in 2017-18 it is very rare and it is a bit of a relief too. The New Contact Form is Here - delabs Contact Form
Question

Question

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.

Using the ULN2003A

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.

Practical Electronics

Practical Electronics
Basic Electronics, EE Reference Resource, Analog, Digital, Power and Electrical.

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